AOBR Radiology flashcards

32 cards. Read the term and the definition here. The deck at the top of this page is optional.

Adrenal adenoma washout

Absolute washout >60% and relative washout >40% at 15 minutes favor adenoma over nonadenoma; unenhanced attenuation <10 HU indicates lipid-rich adenoma.

Bosniak category IIF

Cystic renal lesion with minimal enhancement or thickened septa requiring follow-up imaging; not immediately surgical, unlike categories III and IV.

Closed-loop obstruction

Bowel obstruction with a U- or C-shaped fluid-filled loop and mesenteric whirl, at high risk for strangulation and requiring urgent surgical evaluation.

Suspicious thyroid nodule features

Hypoechogenicity, irregular margins, microcalcifications, taller-than-wide shape, and extrathyroidal extension each raise malignancy risk and support biopsy.

Hepatic hemangioma enhancement

Peripheral nodular enhancement with centripetal fill-in on delayed phases; MRI shows marked T2 hyperintensity, often called lightbulb sign.

TIPS indications

Transjugular intrahepatic portosystemic shunt is used for refractory variceal bleeding or refractory ascites; severe encephalopathy and right heart failure are contraindications.

Uterine fibroid embolization

Particles are injected into both uterine arteries to infarct fibroids; ovarian artery supply and collateral flow must be assessed; pregnancy and active infection contraindicate.

Postembolization syndrome

Expected fever, pain, and nausea after transarterial chemoembolization; hepatic abscess risk rises with biliary-enteric anastomosis or sphincterotomy.

Right internal jugular access

Preferred site for large-bore central catheters because it gives a straight course to the superior vena cava and lower pneumothorax risk than subclavian.

Embolization material choice

Coils for focal arterial occlusion, particles for capillary-level embolization, and glue or Onyx for high-flow lesions or nidus treatment.

BCLC staging

Barcelona Clinic Liver Cancer staging guides hepatocellular carcinoma therapy; ablation for early small tumors and transarterial chemoembolization for intermediate multifocal disease.

ASPECTS score

Noncontrast CT score quantifying early ischemic change in middle cerebral artery territory; lower scores indicate larger infarct and worse prognosis.

Brain abscess diffusion

Ring-enhancing lesion with restricted diffusion centrally (dark ADC), which distinguishes it from most necrotic tumors that do not restrict.

Empty delta sign

Contrast-enhanced CT finding of cerebral venous sinus thrombosis, showing a filling defect surrounded by enhancing dura in the sagittal sinus.

Dawson's fingers

Sagittal FLAIR finding of perivenular demyelinating plaques perpendicular to the lateral ventricles, characteristic of multiple sclerosis.

Glioblastoma imaging

Irregular thick ring enhancement with central necrosis and surrounding edema; IDH-wildtype and MGMT promoter status guide therapy.

Hemorrhagic transformation types

Petechial hemorrhage (HI1/HI2) versus parenchymal hematoma (PH1/PH2); PH2 with mass effect carries the worst prognosis after infarction.

Subarachnoid hemorrhage workup

Hyperdense basal cisterns on noncontrast CT; if CT is negative and suspicion high, lumbar puncture showing xanthochromia confirms.

Pyloric stenosis ultrasound

Pyloric muscle thickness >3 mm and channel length >15 mm in an infant aged 3-6 weeks with nonbilious projectile vomiting.

Intussusception enema

Air or contrast enema is diagnostic and therapeutic for ileocolic intussusception when there is no perforation or peritonitis; target sign on ultrasound.

Malrotation with volvulus

Upper GI series shows a corkscrew duodenum; bilious vomiting in a neonate is a surgical emergency requiring urgent operative repair.

Necrotizing enterocolitis signs

Pneumatosis intestinalis, portal venous gas, and pneumoperitoneum in a premature infant; perforation requires surgical intervention.

DDH ultrasound criteria

Alpha angle <60 degrees or femoral head coverage <50% is abnormal; ultrasound is used before femoral head ossification; Pavlik harness for early cases.

Wilms versus neuroblastoma

Wilms tumor arises from kidney and displaces it; neuroblastoma is adrenal, calcifies, and crosses the midline.

Pediatric CT dose

Use weight-based protocols and prefer ultrasound or MRI when feasible to reduce lifetime radiation dose in children.

BED formula

Biologically effective dose = nd(1 + d/(alpha/beta)); tumor alpha/beta ~10 Gy and late normal tissue ~3 Gy; larger fractions raise late toxicity.

Head and neck chemoradiation

Concurrent chemoradiation improves survival; about 70 Gy for gross disease and 60-66 Gy for high-risk postoperative beds.

Lung SBRT

Stereotactic body radiation for early-stage NSCLC uses high dose per fraction; central tumors carry higher toxicity risk than peripheral tumors.

Spinal cord tolerance

Conventional fractionation limits cord dose to about 45-50 Gy; exceeding this requires strong justification and careful treatment planning.

Radiation pneumonitis timing

Typically occurs 1-6 months after thoracic radiation; risk rises with mean lung dose and V20; steroids are used for symptomatic cases.

Prostate hypofractionation

Fewer, larger fractions deliver similar biochemical control with comparable late toxicity when planned carefully, using dose escalation principles.

Breast conservation radiation

Whole-breast radiation after lumpectomy reduces local recurrence; accelerated partial breast irradiation is an option for selected early-stage patients.