Imaging 3.0: How spectral CT can help
83 y.o. male with ischemic cardiomyopathy (EF 38%), CAD, chronic kidney disease (stage 3), aortic stenosis s/p TAVR admitted for abdominal pain, nausea and vomiting. Estimated GFR 43 mL/min/1.73 m2 BSA. CT angiogram of the abdomen with reduced contrast load, requested after radiologist and physician consultation.
Scan performed with 60 mL injection at 4 mL/sec, using 50% contrast (30 mL contrast load). Mesenteric vasculature is patent. Diffusely dilated loops of small bowel, with a focal cluster of hyperdense loops with engorged mesentery in the right upper quadrant in a radial configuration. A closed loop obstruction was called, and patient taken to the OR urgently.
Is the hyperdense closed loop inflamed, or is it something else? On spectral analysis, virtual non-contrast shows bowel wall in the closed loop remains hyperdense, suggestive of hemorrhage. There is no iodine uptake in the closed loop. On surgery, a 20 cm closed loop "black, purple, and necrotic appearing" was found. Bowel resection and primary anastomosis was performed. Path confirms a completely necrotic loop with transmural hemorrhage
Spectral CT can help with "imaging 3.0". The exam was done is a safer fashion, after radiologist consultation, using a lowed dose of iodinated contrast. Virtual non-contrast eliminates the need for a true non-contrast phase, reducing radiation dose (admittedly, not of primary importance in a 83 year old, but the principle stands). The combination of virtual non-contrast and iodine map (even with reduced contrast load) enables a prompt diagnosis of closed loop obstruction with hemorrhagic necrosis (truly an actionable report), expediting surgery and correlating beautifully with pathology.
Patient did fine post-op, GFR at discharge was 66 mL/min/1.73 m2 BSA.