A hospital's diagnostic stewardship committee is reviewing five complex clinical cases to evaluate physician adherence to evidence-based imaging guidelines. Based on patient-specific risk factors, contraindications, and the acuity of each condition, which imaging modality represents the definitive next best step for each scenario? Match each patient presentation to the single most appropriate imaging study.
- A 29-year-old gravid patient at 32 weeks gestation complains of sudden, sharp, right-sided chest pain and shortness of breath. Her chest radiograph is unremarkable, and bilateral lower extremity compression venous ultrasounds are negative for deep vein thrombosis.Ventilation-perfusion (V/Q) scan of the lungs
- A 71-year-old man with a non-MRI compatible cardiac pacemaker and stage 4 chronic kidney disease complains of rapidly progressive weakness in both legs, sensory loss up to the umbilicus, and new-onset urinary retention.Non-contrast CT myelography of the spine
- A 68-year-old man with persistent atrial fibrillation not on anticoagulation complains of agonizing abdominal pain that seems disproportionate to his relatively benign physical examination. Blood work reveals a lactate of and a creatinine of .Computed tomography (CT) angiography of the abdomen and pelvis
- A 24-year-old woman is evaluated for right lower quadrant abdominal pain, fever, and leukocytosis. A pelvic ultrasound is technically limited due to bowel gas and fails to visualize the appendix. She reports a prior anaphylactic reaction to iodinated contrast media.Magnetic resonance imaging (MRI) of the abdomen and pelvis without intravenous contrast
- A 44-year-old man with a history of heavy alcohol consumption is admitted with intense epigastric pain radiating to his back. His serum lipase level is elevated to five times the upper reference limit. He is hemodynamically stable and it has been 4 hours since his symptom onset.Right upper quadrant abdominal ultrasound
Answer
The correct pairings align each patient's presentation with an imaging modality that navigates specific clinical contraindications: Pregnant PE with normal CXR matches to V/Q scan; Spinal cord compression with pacemaker matches to CT myelography; Mesenteric ischemia with AKI matches to CT angiography; Appendicitis with iodine anaphylaxis matches to non-contrast MRI; and early acute pancreatitis matches to RUQ ultrasound.
Each scenario tests a specific, high-yield exception or rule in imaging guidelines. V/Q scans are preferred in pregnancy if the CXR is normal. CT myelography is the backup for spinal cord evaluation when MRI is contraindicated. Life-threatening vascular emergencies require IV contrast regardless of renal function. Non-contrast MRI is an excellent substitute for appendicitis evaluation when IV contrast causes anaphylaxis. Finally, RUQ ultrasound, not CT, is the necessary imaging for newly diagnosed acute pancreatitis to identify gallstones.
Step-by-Step Solution
Key Concept
Advanced imaging sequencing requires navigating absolute contraindications (e.g., pacemakers, anaphylaxis), physiologic states (e.g., pregnancy), life-threatening priorities (e.g., suspected bowel ischemia overriding AKI concerns), and avoiding premature unnecessary testing (e.g., early CT in pancreatitis).