Ped NM Flashcards
PET
Radiation burden reduce 50%
2.5 MBq/kg
0.2 mg/kg fusid to increase urine extraction
CT
Dose length product converted into effective dose values
Pitch >1
Slice increment = slice thickness, no overlap
Activate dose modulation system
SPECT/CT
Reduce scan length
Can rule out malignant bone lesions
Evaluate soft tissue involvement
Bone scan radiation dose
<3 mSv
F-fluoride PET
Better spatial resolution
Shorter duration of study (max 90 min)
Condylar hyperplasia
Asymmetric growth of mandibular condylar metaphysis
Time for surgery at the end of developing age growth, before arising of degenerative alteration
Bone scan reveal when metabolic activity of metaphysis is declining compared to reference bone
Dynamic renal scan
Tc-MAG3 and Tc-EC
Greater renal extraction - - better visualisation
15-20s/frame for 30-45 min posterior
Static after upright position
Congenital Hydronephrosis
Self-limiting condition without obstruction
Kidney damage - - pyeloureteroplasty
Static renal scan
Pinhole collimator
Postinfection scar - cold defect, triangular
At least 6 months after UTI
Negative scan - - absent or very low reflux - - no need for MCUG
Confirm/Exclude acute pyelonephritis
Cystography
Intravesical administration of Tc
Most sensitive for VUR
Recurrent UTI - - detect and quantify VUR
MCUG is better for first evaluation
#6 French no balloon catheter warm saline mixed with Tc-pert or Tc-SC 15-30 MBq - - bladder max capacity - - remove catheter - - void
Follow up VUR or first exam when bladder dysfunction and urethral anomalies excluded
Cystography protocol
10s/frame filling phase
2-5s/frame voiding phase
Tracer in ureter and renal pelvis - - VUR
Thyroid
Tc-pert or I123-iodide
I131-high radiation burden
Uptake 0.4 MBq
4-6-24-96 h
Thyroid cancer
Secondary after radiotherapy of HL, neuroblastoma - DTC
Primary cancer infiltrates capsule more often than adult - - T3
I131 cumulative activity <18.5 GBq to avoid sialoadenitis
After surgery – radioiodide ablation
Neuroblastoma
Most common extracranial solid tumor of childhood
Adrenal or retroperitoneum
Diagnosed after 1 year - - advanced disease and worse prognosis
I123-MIBG
Diagnostic
Better image quality and lower radiation
159 keV, no beta
T1/2 13h
I131-MIBG
Target therapy
364 keV, beta
T1/2 8 days
Theragnostic
MIBG protocol
Image 24h after IV
Medium energy parallel hole collimator
Reduce septal penetration by 3% photons with high energy photons 400 keV
Prevent blurring
Ant/post WBS, lateral skull, high count spot in abdomen
SIOPEN
Standardized scoring system
Evaluate MIBG uptake
Extension of skeletal disease
Negative MIBG
FDG - - uptake in Waldeyers ring, diffuse thymic uptake, brown fat tissue
FDOPA - higher accuracy and sensitivity than MIBG
FDG indication
Hodgkins lymphoma
Ewing sarcoma
Soft tissue sarcoma
Osteosarcoma
I131-MIBG therapy indication
Inoperable pheo, Paraganglioma, Carcinoid
Stage III or IV neuroblastoma
Metastatic or recurrent MTC
Reserved for patients with uptake
I131 - MIBG therapy dose
100-300 mCi
Lung scan
Tc-MAA or Tc-microspheres
Reduce injected activity and number of particles
Further reduce if right-to-left shunt
Tc-MAA - - reduce to 10000 particles - - reduce risk of systemic embolism
Bronchopulmonary infection
Patchy distribution
Difficult interpretation
Postpone scan if wheezing
Slow injection in peripheral vein
Central line - - hot spot artifact
Cavo-pulmonary anastomosis
Split the dose
Inject multiple sites (upper and lower limbs)
Infant
Avoid anterior view lung
Evaluate shunt
Compare total lung counts with counts from ROI of whole brain
Brain activity should be <1% of lung activity
Main pulmonary trunk stenosis
Scan not sensitive
Combi with echo
Detailed evaluation of central pulmonary bed
Congenital heart disease
Diffuse hypoperfusion
Possible to observe focal perfusion defects - - most frequent cause - peripheral vascular abnormality or surgery (Blalock-Taussig shunt)
Cardio scan
Tc-Sestamibi or Tc-tetrofosmin
Sedation in children <6 y - - fasting
Adenosine 0.14 mg/kg
High resolution collimator with zoom
Indication - anomaly of coronary arteries
ALCAPA - anomalous origin of left coronary artery from pulmonary artery
Post-op follow up
Meckel
Fast 4-6h
Premedication with gastric secretion inhibitor 12-24h before - - reduce release from gastric mucosa
Dynamic anterior 128*128 1min/frame 60 min
Focal spot of uptake simultaneously with stomach
Up to 40-50 min in children
Additional view to avoid urinary activity
GER
Common in infants (incomplete maturation of lower sphincter)
Disappear at 18-24 m
Complications - regurgitation, vomit, dysphagia, wheezing, recurrent pneumonia
Milk scan
Detect GER
Fast 4-6 h
Study when normal feeding time
No sedation (alter motility)
Regular volume of milk
Insufficient volume - - decrease sensitivity for reflux and gastric emptying
Milk scan protocol
1/3 contain tracer
2/3 to wash down activity
Meal should not last >10-15 min - - avoid spillage - - absorbent sheets on lung
Tc-SC 0.5 mCi in children <5y
Can withstand low pH (also DTPA)
Milk scan image
Dynamic 30s/frame over 60 min posterior mouth and upper abdomen + zoom
Fast dynamic study after first swallowing act with child sitting - - 2-3 frames/s for 1 min - - esophageal transit
Late image 2-4h - - gastric emptying and pulmonary aspiration
24h - - pulmonary aspiration during sleep
Cine loop - - activity in esophagus - - GER - - report number of episodes, level and duration
Gastric emptying in older children
Tc-SC added to egg
Fast 4-6h
Meal <10 min. 30s/frame for 60 min
2-3-4h
Salivagram
Aspiration of saliva
Single drop 0.1 ml Tc-SC or DTPA 10 MBq under tongue
Dynamic posterior 128*128 10-30 s/frame 60 min
Oropharynx and thorax
Static with marker on xiphoid, supra sternal notch, axillae
Cine loop
Appear in trachea/bronchi - - note the level
Distal aspiration more relevant
Child abuse finding on bone scan
Scapula fracture
Shin splints
Posteromedial cortex
Lower back pain in young adults
Spondylolysis
Repetitive trauma - - disruption of pars interarticularis
L5
Hyperthyroidism
Graves
6-12 m antithyroid drugs
More radical approach for: severe side effects, non responders, relapse
More common in children
Ectopic thyroid
Lifelong hypothyroidism
Higher dose of L-thyroxine
