Optimal CT Protocol for Visualizing Sclerosing Mesenteritis
Contrast-enhanced CT of the abdomen and pelvis is the imaging modality of choice for diagnosing sclerosing mesenteritis in middle-aged to older adults, with IV contrast administration being essential for accurate characterization of the inflammatory and fibrotic components. 1, 2
CT Protocol Specifications
Contrast-enhanced multidetector CT (MDCT) should be performed with IV contrast during the portal venous phase to optimally visualize the characteristic features of sclerosing mesenteritis. 2 The portal venous phase timing allows for:
- Optimal enhancement of the mesenteric soft tissue nodules and inflammatory changes that define this condition 1
- Clear delineation of vascular involvement and encasement, which is critical for distinguishing sclerosing mesenteritis from malignant processes 1, 3
- Assessment of the "misty mesentery" appearance with increased fat density (mean -62.8 ± 18.6 HU compared to normal subcutaneous fat at -103.9 ± 5.8 HU) 2
Key Diagnostic Features to Identify on CT
The radiologist should specifically evaluate for these hallmark findings:
- Well-defined soft tissue nodules (present in 100% of cases) within the mesenteric fat 2
- Partially hyperdense stripe or pseudocapsule (seen in 72.6% of cases) 2
- Hypodense fatty halo enclosing vessels and nodules (present in 23.5% of cases) 2
- Increased density of mesenteric fat compared to retroperitoneal and subcutaneous fat 2
- Mass effect on adjacent viscera and vessels, which correlates with clinical symptoms 4, 1
Critical Considerations for Older Adults
Do not withhold IV contrast based on moderate renal impairment (GFR >45 mL/min), as the diagnostic benefit substantially outweighs theoretical contrast-induced kidney injury risk in this population. 5 For patients with GFR 59 mL/min (as in typical middle-aged to older adults):
- The diagnostic sensitivity drops significantly without contrast (from 95-99% to 61% for detecting complications) 5
- Recent evidence shows no increased CI-AKI risk in patients with chronic kidney disease receiving IV contrast for CT 6, 5
- Delayed or missed diagnosis carries higher morbidity risk than contrast administration in elderly patients with abdominal pathology 6
Role of MRI as Adjunct or Alternative
MRI with multiple sequences (T2-weighted and contrast-enhanced T1-weighted) should be considered when CT findings are equivocal or for more accurate staging of the fibrotic versus inflammatory components. 7 MRI is particularly useful because:
- T2-weighted sequences can identify lesions not visible on CT alone 7
- Contrast-enhanced T1-weighted images provide superior tissue characterization of fibrosis 3
- MRI serves as an alternative only when IV contrast is absolutely contraindicated (severe allergy or GFR <30 mL/min with acute kidney injury) 5
Common Pitfalls to Avoid
Never rely on non-contrast CT alone, as it cannot adequately distinguish sclerosing mesenteritis from mesenteric carcinomatosis, lymphoma, carcinoid tumor, or desmoid tumor—all of which require contrast enhancement for differentiation. 1, 3
Always obtain tissue diagnosis via biopsy when imaging is suspicious, as sclerosing mesenteritis has been associated with underlying malignancies including lymphoma, melanoma, and colorectal cancer in up to 17.6% of cases. 4, 2
Use three-dimensional volume rendering and partial maximum intensity projection (MIP) reconstructions to clearly demonstrate the extent of mesenteric involvement and vascular relationships, which is optimal for both diagnosis and follow-up. 1, 3