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radiology > Nukes > Flashcards

Nukes Flashcards

1
Q

knee jerk for ocreotide scan

A

hot spleen & kidneys

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2
Q

I-123 vs I-131

A
  • 1-123 lower E (159 keV)–> higher dose –> 24 hr imaging. 1/2 life 13 hrs. no b-emisison. Cardiac & adr act MC.
  • I-131 high E (~364)–> crummier images. 1/2 life 8d. b-emission
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3
Q

Tc WBC vs In WBC

A
  • both spleen > liver
  • Tc-renal & GI. In does NOT. Higher count –> cleaner
  • WBC- lung (<24 hrs)–> GI.
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4
Q

Tracer localization via chemisorption

A
  • Tc-99 Medronate (MDP)

- binds HYDROXYAPATITE

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5
Q

Tracer localization via facilitated diffusion

A

F-18 FDG

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6
Q

Tracer localization via passive diffusion

A

T-99 sestamibi, tetrofosmin, HMPAO, ECD.

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7
Q

Tracer localization via secretion

A

-T-99 IDA, pertechniate

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8
Q

I-123, 131, T99 pertechnetate- mech of transport

A

I-analog transported via Na/I symported NIS.

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9
Q

K analogues

A

Thallium, Rb (transplant via Na/K ATP pump)

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10
Q

T-99 sestamibi-how is it transported

A

lipophilic cation with affinity to negatively charged mitochondria

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11
Q

ECD vs HMPAO

A

ECD faster clearance from blood pool

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12
Q

preparation bone scan

A

15-25mCi tracer

img at 2-4 hr (let ST clear)

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13
Q

MDP uptake dep on…

A

1) OB act (1˚at cortex)
2) blood flow
3) vitD

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14
Q

normal MDP uptake/localization

A
  • bone
  • kid, bladder
  • breasts,
  • ST
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15
Q

ways of getting free Tc

A

1) no enough Sn
2) air (oxide)
3) H2O–> clumping

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16
Q

Where is free Tc

A
  • stomach
  • thyroid
  • salivary glad
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17
Q

making a good bone scan in setting of poor renal function

A

1) oral hydration 2-6 hrs before

2) 4th phase (24 hr delay)-problem=T99 half life is 6hrs

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18
Q

when does “flare phenomenon” occur. Why. How you know it’s flare?

A

2wk-3 mo

  • bone healing
  • xray: more sclerotis, start improving at 3 mo
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19
Q

persistent visualization skull sutures on bone scan

A

renal osteodystrophy

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20
Q

focal breast uptake on bone scan

A

-cancer

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21
Q

renal cortex hotter than adj lumbar spine on bone scan

A

hemochromatosis

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22
Q

diffuse renal uptake on bone scan

A

crx, urinary obstr

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23
Q

Liver uptake on bone scan

A

1) Al3+ contamination
2) hepatoma, mets
3) amyloidosis
4) liver necrosis

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24
Q

spleen uptake on bone scan

A

-autoinfarcted spleen

+ scattered hot & cold areas from mult bone infarcts

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25
Q

lung uptake on bone scan

A
  • hetrotopic Ca (dystrophic or mets)-classically OS
  • fibrothorax
  • 1˚ lung tumor
  • radiation change
  • sarcoid, berrylliosis
  • wegener’s
  • alveolar microlithiasis
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26
Q

muscle uptake on bone scan

A

rhabomyolysis

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27
Q

diffusely decreased skel uptake on bone scan

A

1) Free Tc

2) bisphos

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28
Q

arterial intravasation on bone scan

A

arterial–> distal

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29
Q

causes insufficiency sacral fractures

A
  • OP

- radiation

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30
Q

when should bone scan be performed to evaluate for fracture in elderly?

A

1 wk

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31
Q

AVN dx tests

A

MRi–> bone scan (if CI or need to image mult bones at once)

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32
Q

Donut sign-AVN femoral head

A

-hot on outside, cool in inside

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33
Q

AVN appearance on bone scan

A

dep on timing

  • early=normal or cold (via interrupted bs)
  • later-hot (at time that radiographs are becoming sclerotic)
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34
Q

hypertrophic osteoarthropathy affects what pt of bone

A

periosteum

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35
Q

donut sign-tumors

A

cystic (GCT, ABC, telangiectasia OS)

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36
Q

benign HOT bone lesions

A
  • abc, gct
  • oo, ob
  • FD
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37
Q

use of PSA in predicting bone mets

A

<10 ng/ml nearly excludes

>100 highly predictive

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38
Q

MC loc for single metastatic lesion

A

spine

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39
Q

Mets on a bone scan

A

1) rarely single (15-20%)
2) super scan
3) MULT, randomly distributed into diff sites

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40
Q

how many dying prostate cancer pts have mets?

A

85%

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41
Q

which nuc medicine scan is bone uptake always abN

A

MIBG, 1-131, ocreotide

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42
Q

where does breast bone met usually go

A

spine

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43
Q

what pt of skeleton does lung cancer met to?

A

appendicular

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44
Q

which scan is most sup at detecting NB bone met?

A

MIBI

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45
Q

what pt of bone does NB met to?

A

metaphysis

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46
Q

what pt of skeleton does osteopokilosis spare?

A

spine & skull

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47
Q

next step: equivocal lesion on bone scan

A

plain film- no corresponding lesion=more concerning –> MRI

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48
Q

radiation change on bone scan

A
  • acute (2-3 mo)-warm

- late (~6 mo)-cold. Persistent.

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49
Q

trickery re: bone scan and no kidneys

A

horseshoe

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50
Q

ways of showing FD on bone scan

A
  • hot mandible

- leg that looks like pagets

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51
Q

superscan causes

A

1) diffuse mets-breast & prostate

2) metabolic-hyperPTH, renal osteodystrophy, Pagets, thyrotoxicosis

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52
Q

cold lesions on bone scan

A

1) late radiation change
2) early AVN
3) infarct (very early or late)
4) anaplastic/lytic tumor (renal, thyroid, NB, myeloma)
5) artifact-prosthesis, PM, etc
6) hemangioma-vairable
7) bone cyst (w/o fx)
8) mature HO

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53
Q

utility of bone scan re: heterotypic ossification

A
  • serial exams to detect if process is active-resect once mature (cold)
  • *still active=higher rate recurrence
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54
Q

F18-NA PET vs T99-MDP

A

F18-Na-cleaner, shorter exam time, more expensive. critical orgn=bladder
-MDP: bone (critical) & kidney, fuzzy

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55
Q

F18-NA vs FDG PET

A

will look similar in pts w/ GCSF or EPO (diffuse bmarrow) but brain uptake on FDG

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56
Q

when would you use Tc99 HMPAO instead of In-WBC for infection? Why not use it all the time?

A

Uses:

1) kids (lower absorbed dose & shorter imaging)
2) small pts-T99 does better in hands, feet

Not all the time:

1) .T99 shorter half life
2) GI and gb act obscures act in those areas

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57
Q

In-WBC-which cells are labeled?

A

90% NP (lymphocytes tend to be killed by radiation)

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58
Q

In-WBC critical orgn

A

spleen

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59
Q

what happens if In-labeled cells fragment?

A

indium binds transferrin-see liver and bmarrow uptake

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60
Q

How is MAA prepared?

A

denaturation of human serum albumin

-give via IV

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61
Q

MAA biologic half life

A

4 hrs

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62
Q

xenon 133 vs Tc99DTPA: gas vs aerosol

A

x=gas

DTPA=aerosol

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63
Q

Xenon 133: KeV, half life and bio halflife, critical orgn

A
  • 81 KeV
  • 5.2 d
  • 30 s
  • trachea
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64
Q

3 phases of xenon 133 administration

A

1) wash in (single max inspiration and breath hold)
2) equilibrium (breathing room air and xenon mix)
3) washout (Breathing normal air)

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65
Q

DTPA administration

A
  • requires more pt cooperation (breath through mouth guard w/ nose clamp for several mins)
  • must do this part before MAA?
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66
Q

quantification studies

A
  • before lung resection/tx

- must use Xe + Tc MAA bc Xe won’t interfere w/ Tc

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67
Q

significance of tracer in brain during v/q scan

A

shunt

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68
Q

MAA particle size and #

A
  • 10-100 micrometers

- 500K

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69
Q

when do you reduce particle amount and why?

A
  • risk a functional PE
  • anyone with fewer capillaries (don’t want to block more than 0.1% of caps, ie: children, 1 lung)- 10-50K in neonates
  • R–>L shunt (don’t want to block caps in brain). 100K
  • pulm HTN
  • pregnant
  • this does not reduce dose-normal dose of Tc added to fewer particles
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70
Q

clumped MAA moa, app

A

blood in syringe

multiple scattered focal hot spots

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71
Q

persistent pulmonary activity during xenon washout

A

air trapping (COPD)

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72
Q

accumulation Xe over RUQ

A

fatty liver

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73
Q

clumping Tc-99m DTPA

A

mouth, central airways, stomach (from swallowing)

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74
Q

what if tracer is in thyroid or stomach on VQ scan?

A

1) free Tc

2) R to L shunt

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75
Q

what do you need to call R to L shunt?

A

tracer in brain

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76
Q

if you suspect a R–>L shunt, how do you alter scan?

A

decreased particles

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77
Q

unilateral perfusion defect of whole lungg, no ventilation defect

A

CT or MR

Ddx= mass (MC), fibrosing mediastinitis, central PE

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78
Q

Gallium vs Indium WBC?

A
  • gallium can bind to NP mets after cells are dead (helpful particularly in chronic inf)
  • spine-gallium
  • abd/pelvis-I-WBC
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79
Q

Gallium-67: production, half life, decay, emitting gamma photopeaks, when do you scan, critical orgn, normal localization?

A
  • cyclotron via bombardment of Zn68 –> complexed with citric acid –> gallium citrate
  • HL 78 hr
  • electron capture
  • 93 KeV (40%), 184 (20%), 300 (17%), 393 (5%)
  • colon
  • liver (highest), MARROW (and cortex), spleen, salivary/lacrimal glands, breasts, GP/thymus (kids)
  • kid/bladder <24 hr (faintly up to 72 hr)
  • <24 hr faint lung, >24 hr faint bowel
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80
Q

when is gallium uptake + in chest?

A

-infection
-sarcoid-active disease, guide bx/lavage graded ag bg lung
-CHF
-atelectasis
-ARDS
-idiopathic pulmonary fibrosis-monitor resp to rx
-immsupp: PCP, bacterial PNA. (-) for kaposi and ?lymphoma
-early drug run-bleomycin, amdiodarone)
-

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81
Q

lambda sign

A

1-2-3 (bilateral hila, R paratracheal LN)

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82
Q

panda sign

A

NP, parotid, lacrimal

*sarcoid, sjogrens, treated lymphoma

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83
Q

FDG-PET pleural talc

A

+ via granulomatous rxn

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84
Q

doses MAA, Xe and DTPA

A
  • 3-5 mi
  • 10-20
  • 30
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85
Q

segmental defect size

A
  • small <25%
  • moderate 25-75%
  • large: >75%
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86
Q

high probability PE (97%, PPV 88%)

A
  • mismatched segmental defects. No associated radiographic abN (excludes clinical mimics).
  • 2+ L
  • 2 L & 2 mod
  • 4 mod
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87
Q

intermediate probability (20-85%)

A
  • 1L mismatch
  • 1-4 M
  • triple match LOWER lung
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88
Q

low probability (5-19%; NPV 84%)

A
  • 1 L or M matched

- UPPER/MID lung triple match

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89
Q

very low probability (2-5%)

A
  • 3- sm perfusion defects
  • non segmental lesions-CMG, diaph elevation, aortic aneurism, pl eff, hila, PM artifact, fissure, bullae
  • fissure/stripe sign-thin line MAA uptake btw perfusion defect and adjacent pleural surface representing intervening perfused lung
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90
Q

CTA vs VQ scan radiation doses to maternal breast and fetus

A
  • CTA: breast 10-70mGy (ACR rec 3mGy/br). Fetal dose 0.1-0.66mGy
  • VQ: breast <0.31 mGy, fetus 0.1-0.37
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91
Q

changes to routine VQ scan in the pregnant pt

A

-perfusion only
-adm 1/2 standard dose
~100K particles

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92
Q

what are the functions of the kidney?

A

80% secretion

20% filtration

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93
Q

Tracers used in renal scintigraphy

A
  • DTPA- Filtration. GFR (small portion protein bound, not filtered–> slightly underestimation)
  • MAG3-Secretion (ERPF)
  • DMSA-binds prox tub cortex-ass cortical integrity
  • GH (glucoheptonate)-structural (binds to cortex) or functional (filtered)
  • critical orgn= bladder (exc dmsa-kid)
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94
Q

how is renal scintigraphy performed and phases

A
  • pst (ant if tx or horseshoe)

- 3 phases-blood flow (~20s), cortical, clearance

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95
Q

symmetrically decreased flow to kidneys

A

technical error (poor bolus)

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96
Q

asymmetrically decreased flow to kidneys

A
  • renal a/v thrombosis
  • acute rejection
  • acute pyelo
  • chronic high grade obstruction
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97
Q

asymmetrically increased renal flow

A

renal artery aneurysm

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98
Q

kidney pathology in which flow is normal

A
  • vasomotor nephropathy- imm after sx, should recover 1st 2 weeks
  • ATN-~wks-mo’s
  • interstitial nephritis
  • cyclosporin tox
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99
Q

how is cortical function/phase of renal scan assessed?

A
  • 1 min (really drinking up that contrast)
  • steep slope :)
  • draw area of interest and background area of interest-correct for background. Can be screwed up if obtained over liver or spleen
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100
Q

how is clearance/excretory function/phase of renal scan assessed?

A
  • reach half peak counts ~7-10 mins

- quantify retention via 20/3 or 20/peak ratio

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101
Q

20/3 or 20/peak ratio

A

peak count at 20 mins vs peak count at 3 (Normal <0.8)

-peak count at 20 vs peak count (N 0.3)

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102
Q

what to do in setting of suspected obstruction. how does this differ from standard renal scintigraphy scan?

A

lasix renogram

  • wait 30 mins after clearance phase. If act still in collecting system-give lasix
  • MAG3 > DTPA (better in pts w/ poor renal function)
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103
Q

lasix renogram exam interpretation-no obs, indeterminate, obstructed

A
  • no obstruction-clears w/o lasix
  • no obs-50%+ w/i 10 mins after lasix
  • indeterminate: w/o 50% 10-20 mins
  • obstructed-w/o >20 mins
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104
Q

MCC indeterminate lasix renogram

A

-dilated pelvis (reservoir effect)

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105
Q

false positive “obstruction” on lasix renogram

A
  • poor response to lasix-bad renal function or dyhydration
  • reservoir effect-v dilated renal pelvis (MC)
  • back pressure-full bl, neurogenic bladder (resolve w/ foley)
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106
Q

DTPA vs MAG3 renal fx

A
  • DTPA-GFR, ie: decreased uptake and flow (loss of perfusion pressure)
  • MAG3- secretion tracer (retention)
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107
Q

2 ways of performing ACE-i renogram

A

1) standard dynamic study –> ace-i

2) 1/2 dose baseline study –> full dose

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108
Q

(+) ACE-i renogram

A

->10% worsening

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109
Q

ACE-i renogram study preparation

A
  • stop ACE-i (3-5 d if captopril), CCB
  • NPO 6 hr (for PE ace-i)
  • maintain IV access in case of hypoTN
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110
Q

how would a suspected fluid collection app on renal scintigraphy

A

photopenic (exc urinoma only on DELAYED phase)

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111
Q

renal scintigraphy chronic kidney transplant rejection

A

-no uptake

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112
Q

renal scintigraphy vascular complication (thromb) s/p kid tx

A

-no flow or function

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113
Q

indications for structural renal scintigraphy

A

acute pyelo- (-) uptake)

  • scarring/mass- (-) uptake, scarring decr volume
  • coumn of bertin vs mass-mass=cold
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114
Q

testicular scintigraphy

A

blood flow study

  • torsion vs other cause of pain
  • Na99m-TcO4
  • tape penis up out of way
  • normal= symmetric flow
  • acute torsion=nubin sgx (focal decrease)
  • delayed torsion-halo of increased activity w/ central photopenis
  • abscess-same as delayed
  • acute epididymitis-(+)
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115
Q

trapping vs organification of iodine analogues

A
  • “trapping”-analog transported into glad. I-123, I-131, Tc-99
  • organification-oxidized by thyroid peroxidase, bound to tyrosyl moiety. Tc-99 does not do this
  • only 1-5% Tc-99 taken up by thyroid==> background levels higher
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116
Q

when would you choose Tc-99 over I-analogue?

A

if pt had recent I blocker (ex: I contrast)

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117
Q

when can you resume breastfeeding?: Tc-99, I-123, I-131, fdg 18

A
  • Tc-99: 12-24 hrs
  • I-123: 2-3 d
  • I-131: nxt pregn
  • fdg 18-8 hrs
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118
Q

how much I analogue do you give for uptake test? When do you image?

A
  • 5 microCi 131
  • 10-20 microCi 123

image at 4-6 hr and 24 hr

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119
Q

normal values I uptake. How do you correct for background?

A

4-6 hr: 5-15%
24 hr: 10-35%

correct background prior to 24 hr (use neck counts - thigh counts)

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120
Q

factors that affect I-uptake test

A

1) renal function- (+) stable I pool –> (-) numbers
2) dietary I-variable and controversial
3) meds-Thyroid blockser, nitrates, IV contrast, amiodarone

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121
Q

Causes of increased I uptakes

A
  • graves
  • early Hashimoto
  • rebound after abrupt withdrawal of antithyroid mx
  • dietary I deficiency
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122
Q

Decreased I uptakes

A
  • hypoth
  • renal fx
  • mx (Th blockers, nitrates, IV contrast, amiodarone
  • deiatry iodine overload
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123
Q

which meds decrease I uptake test?

A
  • Thyroid blockers
  • nitrates
  • IV contrast
  • amiodarone
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124
Q

MCC hyperTh

A

graves 75%!

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125
Q

nukes findings Graves

A

-diffuse homog uptakes
*24 hr may be lower/N than 6 hr via rapid TH production
+pyramidal lobe (45%)

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126
Q

Plummer dx

A

Multinodular toxic goiter

-wt loss, anxiety, niosmina, tachycardia

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127
Q

nukes findings multi nodular toxic goiter

A

-heterogenous, moderately elevated uptake

-

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128
Q

toxic vs non toxic MN goiter

A
  • toxic=hot nodules, cold background

- non toxic= moderate/warm nodules, normal background

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129
Q

toxic MN goiter vs graves

A
  • toxic MN goiter=medium high uptakes (<50%)

- graves= high uptake (>50%)

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130
Q

MCC goitrous hypothyroidism in US

A

-hashimotos

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131
Q

nukes appearance hashimotos

A

inhomogeneous focal cold areas

*acute= graves appearance

132
Q

subacute thyroiditis (de Quervains) sequelae

A

-viral prodrome –> hyperTh –> decreased uptake

133
Q

subacute thyroiditis vs graves

A

labs are the same: TSH (-), T3/T4 (+)

SAT low uptake

134
Q

solitary thyroid nodule: how often cancerous if hot vs cold

A

20-40% cold

<1% warm

135
Q

are most thyroid nodules warm/cold?

A

cold, ie: benign

136
Q

discordant nodule

A

hot on Tc-99 but cold on I-123
Cancers can trap but lose ab to organify
need to prove it’s hot on I-123 before calling benign

may be caused by 1) congenital enz deficiency that int organification OR 2) drug blockage: propylthiouracil

137
Q

which thyroid cancer does well with radiation?

A

papillary (+ sx)

138
Q

which thyroid cancer does not do well with radiation?

139
Q

who doesn’t resp well to I-131 radiation therapy

A

1) medullary cancer
2) prior rx- pretreatment dose 50% more
3) hx of methimazole rx (even if yrs ago)

140
Q

ideal thyroid uptake after sx?

A

<5% (assume some thyroid is leftover after sx)

*>5% =painful ablation (steroids, NSAIDs), return to OR

141
Q

ideal TSH prior to I-131 treatment

A 
ideally 50 (30 is minimum)
-want TSH super high--> residual cancer/thyroid tissue really thirsty
142
Q

medullary subtype nukes

A
  • cold on thyroid scan
  • MIBG, ocreotide + (NE org)
  • PET+ as aggressivenss/calcitonin+, ie: calcitonin > 1000 –> PET sensitive. Calcitonin <500, not good
143
Q

how do you get post op TSH up?

A

1) stop thyroid med

2) recombinant TSH “Thyrogen”

144
Q

how do you decide on post op I-131 dosing

A 
depends on stage
100 for thyroid only
150 for thyroid + nodes
200 for distal
*test before letting pt go home to see if they need to go to hospital
145
Q

when do pts need to be admitted after I-131 rx?

A
  • 33 mCi residual activity

- NRC: 7 mR/h measured 1 m from pt’s chest

146
Q

possible side effects of I-131 rx

A
  • pulmonary fibrosis if given with lung mets

- Sjogrens-salivary gland damage. DOSE RELATED

147
Q

routes that body uses to eliminate I-131?

A

mainly urine

-sweat, tears, saliva, breast milk

148
Q

precautions at home s/p I-131 rx

A

*for 3 days

  • water
  • hard candy (keep radio tracer from jacking your salivary glands)
  • distance from others
  • bathroom hygiene (flush twice, sit down if male)
  • disposable uteinsils
  • wash clothes separately
149
Q

when to get pregnant and resume breast feeding s/p I-131 rx

A
  • 6-12 mo before getting pregnant

- no more breast feeding this round

150
Q

absolute CI to I-131 rx

A
  • severe uncontrolled thyrotoxicosis

- pregnancy

151
Q

healthcare workers participating in I-131 rx

A
  • thyroid check 24 hrs later

- RSO inspect room after dc if admitted

152
Q

uptake in liver on I-scan

A

post treatment scan

153
Q

how to monitor for recurr s/p I-131 rx

A

thyroglobulin (anything >0!)

154
Q

I-131 and dialysis

A

adm imm after dialysis to maximize time I-131 on board

  • (-) dose (not excreted until next sash)
  • dialysate down sewer. Tubing stay in store
155
Q

I-131 for hyperTh- dosing

A
  • 15 mCi for Graves (more vascular)
  • 30 mCi for multi nodular (harder to treat the capsule)

-should resolve 3-4 mo

156
Q

why don’t you treat if pt is in severe thyrotoxicosis

A

risk thyroid storm

-can cool them down w/ mx (bb, methimazole)

157
Q

when do you not use methimazole?

A
  • allergy
  • neutropenia
  • pregnancy (use PTU)
158
Q

exophthalmos and I-131 rx

A

some say don’t

159
Q

wolff-chaikoff Effect

A

large ingestion/infusion I –> TH (-)

160
Q

MCC hyperPTH

A
  • adenoma (85%)
  • HP (12%)
  • cancer (3%)
161
Q

two techniques to localize PTH lesions

A

1) dual phase

2) dual tracer

162
Q

dual phase PTH scan

A
  • Tc-99 sestamibi

- 10 min (thyroid + PTH uptake) and 3 hrs img (abN PTH uptake)

163
Q

what does sestamibi dep on?

A
  • mitochondrial density

- blood flow

164
Q

false positive dual phase PTH scan

A

1) thyroid nodule
2) h/n cancer
3) LAD

165
Q

dual tracer PTH scan-tracers, positive

A

1) Something that goes to thyroid and PTH (Tc-99 sestamibi or 201-thallium chloride)
2) only to thyroid (I-123, pertechnetate)

(+) on subtraction = PTH abn

166
Q

problems with dual tracer technique

A

1) more tracers
2) motion not tolerated well by subtract img
3) things that mess w/ thyroid img

167
Q

False positives and negatives of dual tracer technique

A

FP: 1) thyroid adenoma (MC) 2) thyroid cancer 3) parathyroid cancer

FN: small sized adenoma (MC), 4 gland HP.
*consider if negative study in setting of abN labs

168
Q

MIBI (+) LN

169
Q

breast specific gamma img (BSGI)

A

uses MIBI bc focal uptake is abN

170
Q

ways of img brain in nukes

A

1) planar (brain death only)
2) spect
3) PET
* planar and spect use lipophilic agents proportional to bf, which should mimic metabolism
- pet proportional to metabolism

171
Q

agent of CNS nukes

A

*all perfusion (mimicking met)

  • HMPAO, ECD
  • extracted, used for parenchymal img
  • neutral and lipophilic-cross BBB. Unstable lipophilic forms cover to hydrophilic state-trapped
  • GM > WM

-DTPA-not extracted/used for parenchymal img, ie: no SPECT

172
Q

HMPAO

A

hexamethylpropyleneamine oxime

173
Q

ECD

A

ethyl cysteine dimer

174
Q

SPECT

A

single positron emission CT

175
Q

HMPAO vs ECD

A

ECD:

  • slower washout, better blood clearance (better brain to background ratio), preferred in stroke img
  • 15-30 mins ideal img
  • parietal, occipital
  • no intracerebral redistribution

HMPAO:

  • faster washout
  • 15 min-2 hr ideal img
  • FL, thal, cerebellum
  • Tc-99m HMPAO preferred since it accumulates in brain parenchyma within 2 min and takes several hours before significant redistribution
176
Q

angiographic tracer of CNS nukes

A

Tc-DTPA (bc stays in blood)

-main uses: shunt, NPH, brain death

177
Q

how soon after seizure is tracer adm?

178
Q

tracers for seizure localization

A
  • HMPAO, ECT

- PET less practical

179
Q

Thallium 201-production, decay, half life, E peaks, route of transport, high yield uses, normal uptake

A
  • cyclotron
  • electron capture
  • 3 d(73 hrs)
  • 69 & 81 keV
  • K analog, active transport (require living cell)

-thyroid, SG, lungs, heart, skel m, liver, spleen, bowel, kidneys, bladder

uses:

  • cardiac viability
  • toxo- (-)
  • lymphoma (+)
  • kaposi (+) (gallium-)
  • tumor (+)
  • necrosis (-)
180
Q

cns nuke tracers for tumors (diff from dementia or seizures)

A 
201 TI (mc)
99Tc-sestamibi
    • in tumor > inflamm
  • scalp=control
181
Q

gallium+ cns

A
  • CNS lymphoma
  • Toxo
  • bacterial abs
  • cyrptococcus inf
  • Tb

*kaposi= (-)

182
Q

what to use to differentiate lymphoma from toxo?

A

thallium
Lymphoma (+)
Toxo (-)

183
Q

“nose sign”

A

ext carotid –> maxillary branches

*can’t be used to call brain death

184
Q

what should be checked to confirm brain death

A 
kidneys (adequate uptake)
injection site (no extrav)
185
Q

stroke on SPECT-acute, subacute, chronic

A

acute= cold
SA- warm (luxury perfusion)
chronic=cold

186
Q

luxury perfusion

A

paradoxical vascular dil/blood flow in relatively avascular infarcted brain
-48-72 hrs, aka “subacute stroke”

187
Q

utility of nukes in TIA

A

cerebrovascular reserve via adm acetazolaide (Diamox) (vasodil) –> perfusion tracer

  • areas maxed out on auto regulatory vasodilator less intense
  • may benefit from revascularization
188
Q

nukes study for dementia

A

FDG PET

*HMPAO and ECD can be used. FDG great renal clearance (good target to background images), resolution PET > SPECT)

189
Q

normal brain on FDG PET

A
  • symm
  • BG >15% cortex
  • cerebellum <15% cortex
  • thal= cortex
190
Q

FDG PET alzheimers

A

parietotemporal (-)

  • pst cingulate gyrus first abN
  • ID to PD!
191
Q

FDG PET multi infarct dementia

A

scattered (-)

192
Q

FDG PET dementia w/ Lewy bodies

A
  • OL (-)

- preservation mid pst cingulate gyrus (“cingulate island sign”)

193
Q

cingulate island sign

A

preservation of mid pst cingulate gyrus in dementia w/ lewy bodies

194
Q

cingulate gyrus

A

The cingulate gyrus is the curved fold covering the corpus callosum. A component of the limbic system, it is involved in processing emotions and behavior regulation. It also helps to regulate autonomic motor function.

195
Q

FDG-PET picks/frontotemporal dementia

A

FL/TL (-)

-mimics depression!

196
Q

FDG-PET neurodegenerative disorders

A

spare motor strip

197
Q

CSF nukes img-tracer

A

111 In - DTPA

*intrathecal adm

198
Q

abN CSF nukes study

A

1) tracer in Vt (via reflux) (ex: NPH)

2) failure to clear from cisterns and localize over convexities by 24 hrs

199
Q

normal CSF nukes study

A

1) 0 hr: adm
2) 2-4 hr: basal cistern
3) 4- 24 hr: Sylvian fissure, interhem cistern
4) 24 hr- over convexities, cleared from cisterns,

200
Q

NPH CSF nukes study

A

early entrance and persistence in LVt

delayed ascent to parasag region (>24 hrs)

201
Q

NPH MRI findings

A
  • periVt T2/FLAIR +
  • aquaducteal flow void
  • thinning/bowing of cc
202
Q

NPH vs non-obstructive communicating hydroceph

A

NPH has normal opening P on LP

203
Q

CSF leak sites

A

1) cribriform plate and ethmoid sinus
2) sella turcica into sphenoid sinus
3) ridge of spehnoid to ear

204
Q

how to test for CSF leak in nukes

A

1) img basilar cisterns (1-3 hrs)

2) nasal pledgets- (+) if tracer in pledgets:serum > 1.5

205
Q

shunt patency

A
  • tracer in peritnoeum=distal end patent

- tracer in Vt-proximal end paten (can force it in by squeezing distal limb)

206
Q

shunt occlusion

A
  • prox: no tracer in Vt or it’s there but doesn’t clear

- distal: delayed tracer in peritoneum (>10 mins)

207
Q

gold standard for gastric motor function

A

gastric emptying study

208
Q

what pt of menstrual cycle should gastric emptying be performed?

A

first 10 d

209
Q

what’s more sensitive: solids or liquids

A

solids (but some emptying problems may be liquid only)

210
Q

what has lag phase? solids or liquids

A

solids (stomach grinding up food)

-5-20 mins

211
Q

artifactual increased counts in gastric emptying

A

attenuation correction as food moved back and forth btw stomach

212
Q

which drugs should be stopped prior to gastric emptying study and when?

A

*2 d before

1) prokinetics (metoclopramide (reglan), tegaserod (zelnorm), erythromycin, domperidone (motilium)
2) opiates
3) anticholinergic/antispasmodic-donnatal, bentyl, robins, levsin
4) CCB
5) antacids

serotonin rec antags (classically ondansetron/zofran) are okay!

1/2 insulin morning dose (avoid hypoglycemia, schedule early morning)

213
Q

GI bleed scan vs angiogram sensitivity

A

nukes: 0.1 ml/min

angiogram-1 ml/min

214
Q

to what pt of Hbg is t-99 tagged?

A

b-chain

*must first be reduced via stannous ion (tin, tinning)

215
Q

ways in which T99 is tagged to RBC

A

1) in vivo
- tin injected
- Tc-99 pertechnetate injected
- tin bind Hb –> reduces Tc –> Tc bind Hb
* 60-80% bound –> lots of free Tc ==> dirty images
* worse if tubing heparinized or recent IV contrast given

2) in vivo-in vitro–binds 85%
- tin injection
- blood withdrawn (15-30 mins). added to Tc-99 and anticoagulant
- reinfected 10 mins later

3) in vitro (98% binding, $$$)
- blood withdrawn –> added to tin & Tc-99 kit –> reinject

216
Q

how is GI bleeding scan obtained?

A

dynamic (as opp to static, transmission, spect or dual tracer)

217
Q

GI bleed fake outs

A
  • hydro
  • tx kid
  • varices/angiodysplasia
  • penis
  • hemangioma (over liver or spleen)
  • free Tc in stomach

*THESE THINGS SHOULD NOT MOVE

218
Q

+ GI study

A

1) extravasc
2) move (distal colon=exception)
3) intensity +

219
Q

alternative ways of doing a bleeding scan

A

Tc sulfur colloid-fast clearance (scan w/I 30 mins), blind spots (stomach, splenic flexure, hepatic flexure)
-pros: less prep, good target to background

220
Q

how many meckel’s diverticulum will take up Tc99-pertechnitate

221
Q

when should you do a meckel’s scan?

A

when they’re not bleeding

222
Q

how to make a Meckel’s scan better

A
  • pentagastrin-(+) uptake pertechnetate by gastric mucosa
  • H2 blockers (cimetidine, ranitidine)-block secret of pertechnetate out of gastric cells
  • glucagon-slows gastric motility
223
Q

false positive and negative Meckel’s scan

A
  • FP: bowel irritate (recent scope, lax use)

- FN: recent in vivo labeling of RBCs, recent barium study (attenuated)

224
Q

what changes about tracer dosing in setting of hyperbilirubinemia

A

give higher doses

225
Q

HIDA scan prep

A
  • NPO 4 hrs
  • eaten w/I 24 hr (if too full, won’t let tracer in) (CCK)
  • hold narcotic for 6 hr (or 3 half lives)-trigger sphincter of oddi contraction –> delays bowel visualizeion
226
Q

time line normal hida scan

A

liver ~5 mins

GB/ bowel -20-60 mins

227
Q

time line abN hida scan

A

bowel but no gb w/I 4 hrs
OR
no gb at 30mins-1 hr + morphine

228
Q

cystic duct sign

A

nub of activity in cystic duct ass w/ acute cholecystits

229
Q

rim sign

A

gangrenous cholecystitis (20%)

230
Q

biliary obstruction

A

“liver scan sgx” via back P in CBD

-no gb, bile ducts, or bowel

231
Q

showing chronic cholecystitis

A

1) delayed GB filling-not seen at 1 hr but seen at 4

2) EF < 30% w/ cck stim

232
Q

Decreased EF

A

1) chronic cholecystiitis

2) acute acalculus cholecystitis

233
Q

dosing cck and morphine

A

cck: 0.02 µg/kg over 30-60 mins, 15-30 min before the exam
morphine: 0.02-0.04 mg/kg over 30-60 mins, max 3mg

*should never inject these w/I 30 mins of one another

234
Q

drug induced cholecystatic jaundice

A

prompt uptake, delayed excretion

  • chlorpromazine, erythromycin, birth control (estrogens), anabolic steroids, statins (sometimes)
  • may mimic biliary obstrcution
235
Q

biliary atresia vs neonatal hepatitis

A

tracer in bowel=hepatitis

*if you don’t see it in bowel, delayed img at 24 hr

236
Q

reappearing liver sign

A

-labeled dil track sup into peri-hepatic space, coat surface of liver giving appearance of paradoxically incr act in liver after initial decrease from livery emptying into bowel

237
Q

elevated bilirubin

A
  • > 5 mg/dl
  • may be suggested with increased renal activity
  • suggest DISIDA or BROMIDA over HIDA (increases non-dx/inconclusive/FN exams
238
Q

sulfur colloid liver scan

A
  • FNH 40% hot, 30% cold, 30% neutral
  • regenerating nodule
  • hot quadrate lobe (SVC/innominate vein obstr)
  • hot caudate lobe (Budd-Chiari)
239
Q

liver lesion RBC +

A

cavernous hemangioma

  • > 1.5 cm
  • ant, pst img; 30 mins-3 hr
  • hot on delay, ø immediate flow or pool
  • FN: small size (MC), partially fibrosed hemangioma, close to vascular structure, perceived increased act on flow img
240
Q

Gallium + liver lesions

A

HCC

abscess

241
Q

Xe hot liver lesions

242
Q

size of particles of sulfur colloid scan

A
  1. 1-1.0 µm
    - too big-spleen eat them and stuck in lungs)
    - too small-bone marrow eats them.
243
Q

colloid shift

A

sulfur colloid uptake by spleen or bmarrow in setting of:

  • diffuse hepatic dysfunction, portal HTN, hypersplenism, mbar activation
  • most specific causes: cirrhosis, diffuse liver mets, DM, blunt spleen trauma
244
Q

diffuse pulmonary activity in sulfur colloid scan

A
  • excess aluminum

- primary pulm issues (reflecting phagocytosis by pulm MPs)

245
Q

renal act on sulfur colloid scan

A
  • CHF mc (decreased renal bf/filtration P)
  • renal tx-rejection (colloid trapped in fibrin thrombi of microvasc)
  • COxB, DIC, TTP
246
Q

hemangioma vs Angiosarcoma

A

angio hot on immediate flow or pool

247
Q

focal fat

A

Xe+

SC (-)

248
Q

SUV =

A

(FDG concentration at time T) / (dose/body wt)

> 2 generally abN

249
Q

high bg

250
Q

eff of insulin

A

drives into m

251
Q

when do you img fdg-pet ct following rx?

A
  • 2-3 wks after crx
  • 8-12 wk s/p radiation
  • avoid stunning induced Fns and inflamm induced FPs
252
Q

reducing brown fat

A

1) warm room
2) propranolol, reserpine, diazepam
3) high fat/low carb diet

253
Q

hibernoma

A

focal brown fat

-ddx=liposarcoma, so resected

254
Q

obesity eff on SUV

A

higher (fat takes up less llc)

255
Q

Ki67 proliferation index

A

+ = more aggressive tumor

256
Q

where do you inj FDG in setting of breast cancer?

A
  • opp side

- pt supine, arms up

257
Q

when do you use FDG-pet for breast cancer screening

A

if CI to MRI

258
Q

FDG cold tumors

A
  • BAC
  • carcinoid/NE (low/intermed grade)
  • 50% RCC
  • perotneal bowel/liver implants-small and adj bowel
  • perivesicular dx-missed by adj bladder
  • mucinous anything
  • prostate
  • 60% HCC (variable g6p that can’t trap FDG
  • nonseminomatous testicular CA (or Luke warm)
  • MALT lymphoma
  • necrotic or cystic tumors
259
Q

which renal tumor is FDG hot

A

oncocytoma

260
Q

diffuse thyroid FDG+

A

hashimotos

261
Q

seminomatous vs non-sem CA

A

non-sem cold/Luke warm

-sem=hot

262
Q

metformin eff on fdg

A

large > small bowel uptake

*hold for 48 hrs

263
Q

FDG avid bowel spots

A

cancer

villous adenoma

264
Q

FDG NETs

A

high grade

265
Q

FDG pit adenomas

A

benign ones are hot

-horm w/u and MRI

266
Q

when is adrenal FDG uptake abN

A

> liver…variable

-compare to non-con ct (<10hu)

267
Q

FDG in sarcoid

A

cardiac

-can use as 1˚dx test or if bx failed

268
Q

recurr lymphoma vs thymic rebound

A

recurr lymphoma=hot; round

-thymic rebound= warm; normal thymus shape

269
Q

lymphoma fdg

A

usually hot

-MALT = low avidity

270
Q

FDG endometrium

A

1) 1-4
2) ovulation (d 14)
- diffuse
- premeno

271
Q

FDG endom: normal vs cancer

A

cancer= focal, post meno

272
Q

FDG ovaries

A

ovulation

  • ovoid rim w/ photogenic center
  • premeno
273
Q

benign FDG+ gyn lesions

A

-fibroids
endom cysts
-vesicovag fistula- urine spilled.
-misregistration in bladder/ureters-avoid by minimizing time btw PET and CT

274
Q

use of FDG w/ osteosarcoma

A
  • SUV Max (bc very heterog tumor); higher=higher grade; predictor of overall survival
  • response to neoadj rx (FDG taken up by viable tumor)
  • not used for screening bc so non-spec
275
Q

Indium 111-prod, decay, peaks, half life, moa, uses, labelling process

A
  • cyclotron
  • electron capture
  • 67 hr
  • 173 and 247 keV
  • Fe+ analog

-bind to WBC, ocreotide or DTPA (CNS img)

  • must first be hooked to strong chelator.
  • must isolate WBC prior to labeling (otherwise binds transferrin in blood!)
276
Q

ocreotide scanning uses

A
  • NE tumors:
  • carcinoid
  • gastrinoma
  • PG
  • SCLC
  • medullary thyroid CA
  • merkel cell tumor
  • lymphoma
  • meningioma
277
Q

ocreotide scanning phases

A

early (4 hrs) and delayed

-early: no bowel

278
Q

MIBG

A
  • noradrenalin analog–> taken up by adrenergic tissue
  • pheochromo, PG, NB (bone mets)
  • link w/ I-123, I-131
  • block thyroid with Lugol’s iodine or perchlorate
279
Q

which meds interfere with MIBG?

A
  • CCB
  • labetalol (other bb’s have no eff!)
  • reserpine
  • TCA
  • sympathomimetics
280
Q

brown fat nukes

A
  • FDG-PET-
  • MIBG (sympathetic innervation
  • shoulders, clavicles
281
Q

ocreotide scan in setting of suspected insulinoma

A
  • ocreo can trigger hypoglycemia

- give D50 bf and after or just have it ready

282
Q

ocreotide scan prep if pt on ocreotide

A

stop rx for 3 d before

283
Q

benignity vs malignancy gastronome vs insulinoma

A

gastronoma usually mal

insulinoma usually benign

284
Q

when is ocreotide better than mibg?

A

everything except adrenal pheo, NB

285
Q

what is best choice for non-functional islet cell tumor

A

fdg-pet

*mibg & ocreotide are both crap

286
Q

prostascint

A

111-In label to Ab Capromab Pendetide (ProstaScint) –< PSA

  • rising PSA + negative bone scan-looks for ST mets
  • offers salvage rx (radiation to surgical bed)
  • critical orgn=liver
287
Q

various 111-In scans and critical orgn trivia

A

prostascint-liver

  • wbc-spleen
  • ocreotide-spleen
288
Q

particle size: lymphoscintigraphy, VQ, liver spleen

A

<0.2 microns (<200 nm)

  • 10-100 microns (10,000-100,000 nm)
  • unfiltered-all sizes
289
Q

sentinel node detection

A

10-50 nm Tcc99m-sulfur colloid for melanoma and breast cancer

290
Q

sentinel node detection melanoma

A
  • utility is in lesions 1-4mm depth

- intradermal int in 4 spots around lesion/excison scar–> img

291
Q

sentinel node detection breast cancer

A

superficial or deep into pec m

292
Q

breast specific gamma img

A
  • 20-30 mCi Tc99-sestamibi in Cl arm –> img 20 mins later
  • (foot injection if img both breasts)
  • FP: FA, FC, inflamm
  • FN: deep, <1cm, medial, overlying heart
293
Q

cardiac img tracers

A
  • t T99-sestamibi
  • t99-tetrofosmin
  • thallium (older, redistributes)
294
Q

when to img cardiac tracers

A
  • 30-90 mins for T99

- thallium-10 mins

295
Q

cardiac stress test prep

A
  • NPO 4 hrs (decreased GI bf)
  • stop bb, cab, long acting nitrates for 24 hrs
  • no caffeine ~12 hrs if using adenosine-related perfusion stress agents
296
Q

chemical stressors

A
  • regadenoson-less se’s/bronchospasm than others
  • dipyridamole
  • adenosine-AV block
  • no caffeine

-dobutamine-beta 1 agonist. avoid in LBBB. pt cannot be on bb. Better in pts w/ COPD, asthma or have taken caffeine in 12 hrs

297
Q

LBBB classic artifact on cardiac stress tests and which drug to use

A
  • reversible perfusion defect at septum via improper relaxation during diastolic coronary filling bc discard rhythms
  • need a perfusion drug.
  • Dobumatin causes more FPs (incr HR–> decr septum relaxation)
298
Q

fixed vs reversible defects on img

-fixed with surrounding reversible

A
  • fixed=scar
  • reversible=ischemia
  • infarct w/ peri-infarct ischemia
299
Q

LV cavity larger on stress vs rest

A

transient ischemic dilation

-diffuse SE hypo perfusion-correlates with hi risk dx (L main or 3 vess)

300
Q

fixed cavity dilation

A

dilated cardiomyopathy

301
Q

RV activity on rest

A

RV hypertrophy

302
Q

lots of splanchnic act on cardiac stress

A

-not stressed enough

303
Q

stunned myocardium

A

perfusion +, contractility (-)

304
Q

hibernating

A

perfusion (-), contributed (-) , FDG+, thallium redistribution

305
Q

hibernating vs scar

A

hibernating takes up FDG and redistributes thallium

306
Q

multicoated acquisition scan (MUGA)

A

angiogram using tagged RBCs that is gated

  • calculates EF (more accurate than myocardial perfusion for LVEF)
  • performed in LAO (best septal view)
  • falsely low EF: LV overlapped w/ LA or RV OR LA is big
  • falsely high EF-ROI over spleen (wrong subtraction)
307
Q

rubidium 82 & NH3

A

PET myocardial perfusion

1/2 life 75 s vs ~10 mins

308
Q

Regadenoson

A

adenosine rec agonist

few se’s.

309
Q

dipyridamole

A

inh bd of adenosine

310
Q

adenosine

A

vasodilator

-aminophylline=antidone

311
Q

agents for bone pain ass w/ metastatic disease from breast, prostate cancer

A

1) Sr 89-Cl
2) Sm-153 ETMP
3) Ra-223 dichloride

312
Q

Absolute CIs to Sr and Sm bone pain rx

A
  • pregnancy
  • breast feeding
  • renal fx
313
Q

Strontium-Sr89 (Metastron)

A
  • complexes with hydroxyapatite
  • worst agent, highly myelotoxic
  • b-emitter
314
Q

samarium-Sm 153 (quadrate)

A
  • complex w/ hydroxyapatite
  • b-decay and 28% via gamma ray (103 kev), ie: used for img
  • renal excretion
  • myelotoxic
315
Q

Sr89 vs Sm153

A
  • SR89: 15-30% drop in platelet and WBC. 8-12 wk recovery

- Sm-153: 40-50% drop, 6-8 wks

316
Q

radium-Ra 223 (xofigo)

A
  • Ca-absorbed at sites of mineralization
  • emits 4 alpha particles (shorter range than Sr, Sm–> less hematog.
  • long half life- 11.4 d (shipping)
  • non hematog tox mc than hematoma (diarr, fatigue, n/v, bone pain)
  • GI excretion
  • IMPROVES SURV! (prostate mets)
317
Q

Yttrium-90

A
  • beta emitter
  • max tissue penetration ~10 mm-spares most of adj liver parenchyma
  • pretreatment lung shunt check-10-20% decrease dose, >20% radiation pneumonitis
  • 20-40 µm (trapped in tumor, but doesn’t block vess/bf
  • dose: 100-1000 Gy delivered (need at least 70 for success)
  • emission: 175 and 185 kev
  • half life: 2.67 d
318
Q

radioimmune rx + y90

A

-for refractory non-hodgkin lymphoma’

  • preop with rituximab to block CD20 recs on circulating cells and in spleen
    1) I-111 labeled Ab (ibritumomab tiuxetan/Zevalin) –< CD20 recs on Bcells==> eval tumor burden
    2) Y90 rx
  • if altered bio distribution, don’t treat
  • mc se’s: TCP, NP (90%), ie: don’t give to pts w/ PC < 100k
  • can be discharged w/ proper care at home
319
Q

% R –> L shunt

A

[(whole body count-lung count)/whole body] x 100%

320
Q

LVEF calculation

A

(end diastolic count - end systolic count)/ (end diastolic counts - background counts)

321
Q

thallium, cardiac img

A
  • high 1st pass extraction 85%
  • quick redistribution-dynamic exchange btw myocardial cytosol and vascular blood pool ie;: post stress img <10 mins post injection and delayed 24 img
322
Q

ddx decreased pulmonary perfusion/absent perf

A

SAFE POEM: Swyer-James syndrome, pulmonary Agenesis/hypoplasia, mediastinal Fibrosis, pleural Effusion, Pneumonectomy, Obstruction by tumor, pulmonary Embolus, Mucous plug.

323
Q

DTPA-uses

A
  • Tc-DTPA-lung vent
  • Tc-DTPA-kidney filtration
  • Tc-DTPA-CSF
  • In-DTPA- liquid emptying
324
Q

Liver scan

A
  • blood pool act, ø excr into bg, gb, or bowel at 60 min
  • obtain 4 and 24 hr delayed img

-hepatitis
-biliary obstruction
-

325
Q

captopril renogram FPs

A

dehydration
-captopril induced hypoT
CCBs

326
Q

en block transplant

A

2 peds kidneys transplanted into adult

radiology (31 decks)

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