Renal Classic NM Flashcards

1
Q

Excreted by glomerular filtration

A

Tc-DTPA

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2
Q

DTPA advantage over CR-EDTA

A

Wide availability
Low cost
Low radiation dose
Gamma ray suitable for gamma camera

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3
Q

Excreted by tubular secretion

A

I123-Hippuran
Tc-MAG 3

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4
Q

MAG 3 excreted

A

By tubular secretion and very small hepatobiliary excretion - - gallbladder activity
Fast blood clearance vs DTPA

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5
Q

Mag3 clearance approximates

A

Effective renal plasma flow

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6
Q

MAG3 indications

A

Children
Transplanted kidney
Impaired kidney function

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7
Q

Cortical binding

A

Tc-DMSA binds to proximal tubular cells

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8
Q

Dehydration cause

A

Delay in intraparenchymal transit and excretion
Drink 7 ml/kg over hour before

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9
Q

Dynamic scan frames

A

Phase 1: 1 frame/sec for 1 min = angiogram, renal perfusion - - normal if renal cortex seen within 1-3 sec after aorta
Phase 2: 1 frame/10 sec for 4 min = parenchymal uptake
Phase 3: 1 frame/20 sec for 15 min = renal excretion

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10
Q

No obstruction

A

Rapid washout
Shape - upward concavity
T1/2 fusid <10-15 min

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11
Q

Obstructive uropathy

A

Normal or delayed angiogram
Delayed time to peak, progressive rise in activity even after fusid
Absent, incomplete or slow washout
No bladder activity
T1/2 fusid >20 min

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12
Q

Uncertain equivocal response

A

Normal angiogram, bladder activity delayed if bilateral
Washout delayed until fusid or postvoid
T1/2 fusid 15-20 min, partial obstruction
Poorly functioning kidney
Hydronephrosis - - reservoir effect
Repeat test with F-15 or calculation of mean transit time

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13
Q

Tracer accumulation in parenchyma is proportional to GFR, ERPF

A

Parenchymal phase

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14
Q

Hilson perfusion index for Transplanted kidney

A

Ratio area over iliac artery / kidney curve
>1.5 - - kidney hypoperfusion - - acute rejection

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15
Q

ROI background

A

Perirenal below lower pole or from upper to lower pole laterally
Caudal and lateral

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16
Q

Transit time

A

Time for passing through single nephron

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17
Q

Tonnensen formula

A

From 50:50 to 43:57
Not accurate for patients with kyphoscoliosis, ptosis, ectopic or malformed kidney

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18
Q

Indication for mean transit time

A

Suspected RAS
Obstruction
Kidney transplant rejection
In these cases mean transit time is prolonged

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19
Q

About GFR

A

Usually becomes abnormal before serum creatinine levels become abnormal (when GFR is reduced by 50%)
Renal function reduced - - creatinine clearance not accurate
Inulin clearance = gold standard, but complex and high cost
Obtained through Tc-DTPA clearance

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20
Q

Two compartment

A

Central compartment - plasma
Second compartment - extravascular space (tracer diffuses and redistributes back into plasma due to concentration gradient)
6 blood samples after tracer injection up to 180 min
Time consuming, require plasma samples

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21
Q

Single compartment

A

Draw blood when redistribution from extravascular to intravascular space depends on renal clearance
Ignore first exponential - - GFR overestimated
Impaired renal function - - error smaller
1-3 blood samples

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22
Q

Methods rely on urine collection

A

Severe renal failure
Ascites
Edema

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23
Q

Angiotensin II

A

Regulation of GFR in renal hypoperfusion caused by RAS and renovascular hypertension

24
Q

ACE inhibitor captopril

A

Cancel adaptation mechanism - - GFR maintained even in presence of RAS due to vasoconstriction of efferent arteriole by Angiotensin II
Causes reduction in GFR - - reduced accumulation and excretion of DTPA, but tubular extraction is not affected - - MAG3 slightly delayed accumulation and no washout

25
Q

Preparation for captopril scan

A

Stop ACE inhibitor and Ca channel blockers 2-7 days
Stop diuretic 1 week
Hydration 7 ml/kg over 1 hour
Fast

26
Q

Captopril scan protocol

A

Dynamic scan
Captopril 50 Mg PO
After 60 min second dynamic renal scan, monitor of BP
DTPA>MAG3

27
Q
A

0 - normal
1 - mild
2 - moderate
3 - severe delayed excretory phase
4 - mild/moderate parenchymal uptake failure
5 - severe parenchymal uptake failure (washout - like curve)
4-5 - - significant reduction of renal function

28
Q

Captopril false-positive

A

Multiple renal arteries
Dehydration (bilateral)
Sodium depletion - - activate renin system
Captopril induced hypotension (bilateral)
Calcium channel blocker (bilateral)

29
Q

Captopril false negative

A

Hemodynamically significant stenosis
Poor function at baseline

30
Q

Positive RAS

A

Normal curve but peak is delayed
Post captopril decreased GFR

31
Q

DMSA indication

A

Acute pyelonephritis
Quantification of parenchymal damage
Assessment of cortical scars
Renal agenesis
Ectopic kidney
Horseshoe kidney
DD Renal mass vs lobular compensatory hypertrophy or prominent column of Bertin

32
Q

Cause of reflux

A

Boys - valve in posterior urethra
Girls - obstruction of bladder neck or uretetocele
Neurogenic bladder with spina bifida
Hutch paraureteral diverticulumy

33
Q

Radionuclide cystography first choice for

A

Girls
After surgery of VUR

34
Q

Cystography radiopharmaceutical

A

DTPA, MAG3, Colloid in saline 250-500 ml
Non absorbable through bladder mucosa
Calculate bladder capacity before
Catheter
Dynamic

35
Q

VUR degree

A

Grade 1 - mild/limited to ureter
Grade 2 - moderate, involve ureter and pelvis without dilation of pelvis
Grade 3 - severe with dilation

36
Q

DMSA should be discarded

A

After 4 h

37
Q

Pressure in glomerulus

A

70 mm Hg

38
Q

Resultant pressure

A

35 mm Hg

39
Q

GFR

A

120 ml/min

40
Q

Renal blood flow

A

1200 ml/min
20% of cardiac output

41
Q

1 day

A

180 L of plasma filtered
90% reabsorbed

42
Q

Extraction fraction

A

DTPA 20%
MAG3 60% - - better quality image
I123-Hippuran >85% - - plasma clearance = renal plasma flow

43
Q

Plasma protein bind

A

DTPA 3-5%
MAG3 80%
DMSA 90%

44
Q

Dose

A

DTPA 200 - 300 MBq
MAG3 100 - 150 MBq
Hippuran 50 - 100 MBq
DMSA 37 - 110 MBq

45
Q

Percent of renal plasma flow cleared by glomerular filtration

A

20%

46
Q

DMSA high radiation dose to kidney

A

Long effective half life

47
Q

DMSA
Lower poles less uptake than upper poles

A

Lower poles more anterior to upper poles

48
Q

Dynamic scan protocol

A

Large FOV
LEHR parallel hole collimator posterior
Matrix 64 or 128 (esp children)

49
Q

Fusid test

A

To distinguish simple dilation of urinary tract (congenital, pelvis atony) vs obstructive disease
Dynamic scan - - static post void - - diuretic test

50
Q

Functional obstruction

A

Washout delayed until fusid
T1/2 fusid <10 min

51
Q

Acute pyelonephritis

A

Larger cortical defect due to edema and ischemia
Only follow up to distinguish
Persists > 6 months - - chronic = scar

52
Q

Conjugate image

A

Geometric mean calculated with anterior ROI flipped on posterior image

53
Q

DMSA protocol

A

37-110 MBq
Image after 2-4h
Hydration while waiting

54
Q

VUR complications

A

Acute pyelonephritis if UTI
Damage to renal parenchyma
Arterial hypertension
Chronic renal failure

55
Q

VUR first diagnostic

A

Fluoroscopic voiding cystourethrography
Boys
Degree of VUR and presence of posterior urethral valve