CT Abdomen and Pelvis Without Contrast (Routine)

Indications

• Suspected urolithiasis / renal colic (CT KUB / stone protocol)
• Contrast contraindication (severe renal impairment, contrast allergy)
• Evaluation of calcifications, hemorrhage, fat-containing lesion (e.g. angiomyolipoma, adrenal adenoma baseline)
• Follow-up of known finding without need for contrast
• Suspected retroperitoneal hemorrhage

Patient prep

• No IV contrast; no oral contrast for stone protocol
• No strict NPO required
• Supine, arms up; for renal colic protocol scan supine (prone optional to confirm UVJ stone vs bladder)

Contrast

Technique

• Supine, arms up; helical volume from dome of diaphragm through pubic symphysis
• Comfortable breath-hold
• 120 kV (low-dose technique for stone protocol; 100 kV in smaller patients); mAs reduced with AEC; iterative reconstruction
• Reconstruct soft-tissue 3-5 mm axial + thin 1.25-2 mm source; coronal and sagittal reformats (coronal valuable for stones)
• For stone protocol use low-dose settings (target reduced CTDIvol)

Series / Sequences

Key points

• Stone protocol is low-dose, non-contrast; report stone size, location, Hounsfield density, and secondary signs (hydronephrosis, perinephric stranding, tissue rim sign)
• Non-contrast baseline is part of adrenal washout and renal mass characterization (≤10 HU lesions)
• Coronal reformats help differentiate phleboliths from ureteral stones (look for soft-tissue rim sign vs comet tail)
• Use when contrast contraindicated or to assess hemorrhage/calcification

References