V/Q Scan — Pulmonary Embolism
V/Q scan is the alternative to CTPA for PE when contrast is contraindicated or when radiation dose matters (pregnancy, young women). RadCall covers the PIOPED II criteria for high/intermediate/low probability, matched vs mismatched defects, and integration with pretest probability.
- PIOPED II criteria — high, intermediate, low probability
- Ventilation-perfusion mismatch — PE pattern
- Matched defect — parenchymal vs pleural cause
- Stripe sign — peripheral perfusion preserved
- Triple match — low probability for PE
- V/Q SPECT — improved sensitivity over planar
- Pregnancy PE — V/Q vs CTPA dose comparison
- Chronic PE — CTEPH on V/Q vs acute PE pattern
HIDA Scan — Hepatobiliary
HIDA scan evaluates biliary tract function and diagnoses acute cholecystitis when ultrasound is equivocal. RadCall covers normal timing values, CCK augmentation for chronic cholecystitis, cystic duct obstruction, bile leak localization, and biliary atresia in neonates.
- HIDA normal timing — hepatic uptake, biliary excretion
- Cystic duct obstruction — non-visualization of gallbladder
- Acute cholecystitis — rim sign, morphine augmentation
- CCK-HIDA — gallbladder ejection fraction (normal >35–38%)
- Chronic cholecystitis — low GBEF with CCK
- Bile leak — free tracer outside biliary system
- Biliary atresia — neonatal jaundice protocol
- Afferent loop obstruction — post-surgical anatomy
Bone Scan
Tc-99m MDP bone scan detects areas of increased osteoblastic activity. Common indications include metastatic disease staging, occult fracture, osteomyelitis, and Paget disease. SPECT/CT improves specificity by correlating tracer uptake with anatomy.
- Metastatic disease — superscan, photopenic mets (myeloma)
- Hot spots — blastic mets, fracture, Paget, arthroplasty
- Cold lesions — aggressive tumors, avascular necrosis
- Osteomyelitis — three-phase bone scan criteria
- Stress fracture — linear cortical uptake
- Superscan — diffusely increased uptake, absent kidneys
- SPECT/CT — anatomic localization of uptake
- Paget disease — expanded bone, intense uptake
Other Nuclear Medicine On-Call Studies
- GI bleed scan — Tc-99m RBC, active bleeding threshold
- Meckel's scan — Tc-99m pertechnetate, ectopic gastric mucosa
- Brain death scan — absent intracranial perfusion
- Thyroid scan — hot vs cold nodule, Graves vs toxic nodule
- Renal scan (MAG3) — obstruction, renovascular hypertension
- Lymphoscintigraphy — sentinel lymph node mapping
- Infection/inflammation — WBC scan, FDG-PET indications
- MIBG scan — pheochromocytoma, neuroblastoma