What is the best imaging protocol for diagnosing sclerosing mesenteritis in a middle-aged to older adult patient?

Best Imaging Protocol for Diagnosing Sclerosing Mesenteritis

Contrast-enhanced multidetector CT (MDCT) of the abdomen and pelvis is the best imaging modality for diagnosing sclerosing mesenteritis in middle-aged to older adults, as it provides the highest diagnostic accuracy for identifying the characteristic "misty mesentery" appearance and associated soft tissue nodules. 1

Primary Imaging Recommendation

Obtain contrast-enhanced MDCT of the abdomen and pelvis as the first-line diagnostic test for suspected sclerosing mesenteritis. 1 This modality demonstrates:

• Increased mesenteric fat density (mean -62.8 ± 18.6 HU) that is significantly higher than normal subcutaneous (-103.9 ± 5.8 HU) or retroperitoneal fat (-105 ± 6 HU), creating the pathognomonic "misty mesentery" appearance 1
• Well-defined soft tissue nodules (present in 100% of cases) within the mesenteric fat 1
• Partially hyperdense stripe (seen in 72.6% of patients) representing fibrotic tissue 1
• Hypodense fatty halo enclosing mesenteric vessels and nodules (present in 23.5% of cases) 1

Technical Protocol Specifications

Perform MDCT with the following parameters:

• Intravenous contrast administration during portal venous phase (50-70 seconds post-injection) to evaluate mesenteric vasculature and tissue enhancement 2, 1
• Thin-slice acquisition (2-3 mm slice thickness) for detailed evaluation of mesenteric structures 2
• Multiplanar reconstruction to assess the full extent of mesenteric involvement 2
• DICOM viewer utilization for precise density measurements and comparison with normal fat attenuation 1

Role of MRI as Complementary Imaging

Consider MRI with multiple sequences when CT findings are equivocal or for more accurate staging of disease activity. 3 MRI provides superior tissue characterization:

• T2-weighted sequences (including fat-saturated images) to identify edema and active inflammation 3
• Contrast-enhanced T1-weighted sequences to detect lesions not visible on CT and assess fibrotic components 3, 4
• Three-dimensional angiography to evaluate vascular involvement and displacement 4

MRI is particularly valuable because different stages of sclerosing mesenteritis (mesenteric panniculitis, mesenteric lipodystrophy, and retractile mesenteritis) may coexist in the same lesion, and MRI can better differentiate these components. 3

When Tissue Diagnosis is Required

If imaging findings are atypical or malignancy (particularly lymphoma or mesenteric metastases) cannot be excluded, perform CT- and ultrasound-guided needle biopsy using the coaxial technique. 5, 6 This approach:

• Allows verification of needle position with CT before specimen collection 5, 6
• Enables multiple specimens to be obtained through a single introducer needle, minimizing trauma 5, 6
• Provides adequate tissue for histological diagnosis while remaining minimally invasive 5, 6

The coaxial technique is particularly useful in elderly patients where the differential diagnosis includes malignancy, as sclerosing mesenteritis can mimic mesenteric metastases from carcinoid tumors or lymphoma. 4

Critical Diagnostic Pitfalls to Avoid

• Do not rely on clinical presentation alone, as the most common symptom is nonspecific abdominal pain (37.2% of cases), and many patients are asymptomatic 1
• Always consider associated conditions that increase prevalence: previous abdominal surgery (33.3%), smoking (39.2%), malignancy (17.6%), hypertension (35.2%), hyperlipidemia (25.5%), and diabetes mellitus (21.5%) 1
• Recognize that sclerosing mesenteritis can mimic malignancy on imaging, particularly mesenteric metastases, requiring biopsy for definitive diagnosis when imaging features overlap 4
• Measure mesenteric fat density quantitatively rather than relying on visual assessment alone, as the significantly elevated HU values distinguish sclerosing mesenteritis from normal mesentery 1

Prevalence and Clinical Context

Sclerosing mesenteritis has a prevalence of approximately 2.43% on MDCT imaging, with a mean patient age of 56.2 years and male predominance (69% male). 1 The diagnosis has increased with widespread use of MDCT and DICOM viewers, making radiologists more familiar with its characteristic appearance. 1