Desmoid tumor MRI

Desmoid tumor Microchapters
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Case #1

Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1] Associate Editor(s)-in-Chief: Sara Mohsin, M.D.[2]Faizan Sheraz, M.D. [3]

Overview

MRI is preferred over CT, especially for truncal and extremity desmoid tumors. On MRI, desmoid tumor has variable characteristics depending on their cellularity and fibrous content with loss of signal following fat saturation. They appear isointense/hypointense on T1 and hyperintense on T2.

MRI

• MRI is required in order to:
  • Define the relationship of the tumor to adjacent structures
  • Assess resectability
  • Find out the need for treatment
  • Monitor recurrence after surgery
• MRI is preferred over CT, especially for truncal and extremity tumors
• MRI characteristics of desmoid tumors are variable depending on their cellularity and fibrous content:
• MRI may be helpful in the diagnosis of desmoid tumor. Findings on MRI diagnostic of desmoid tumor include:

MRI characteristics of desmoid tumors

MRI sequence	Characteristics
T1	Homogeneously isointense Hypointense Mildly hyperintense Low intensity signal
T1 C+ (Gd)	Typically enhances avidly
T2/STIR	High heterogeneous signal Predominantly hyperintense (T2 hyperintensity may diminish over time as tumor cellularity decreases and collagen deposition increases) Hypointense bands may be seen that represent dense collections of collagen bundles With gadolinium administration Desmoids typically show moderate to marked enhancement Hypointense bands may become more apparent because collagen bundles are not enhanced by contrast material
GE	Peripheral areas of smooth low signal intensity that do not represent calcification or hemorrhage are characteristic

A 47-year-old woman with desmoid-type fibromatosis in the right axilla with progression (Group 1). This was misdiagnosed as a sarcoma on preoperative CT but as fibromatosis on preoperative MR. The tumor shows iso-signal intensity on coronal T1-weighted image (A) and high signal intensity on axial T2-weighted image (B). The margin is partially ill-defined (white arrows) on axial T2-weighted image (B). A rim of surrounding fat (white arrows) with high signal intensity is clearly seen on T1-weighted image (A). On enhanced T1-weighted axial (C) and coronal (D) images, the tumor shows strong and heterogeneous enhancement with a central area of nonenhancing low signal bands (black arrows). The maximal standardized uptake value on FDG PET was 2.1 (not shown). CT = computed tomography, MR = magnetic resonance, FDG PET = 18F-fluorodeoxy glucose positron emission tomography.Source: Xu H. et al, Department of Radiology and Research Institute of Radiology, University of Ulsan College of Medicine, Asan Medical Center, Seoul, Korea (HX, HJK, SL, JWL, HNL, MYK); Department of Radiology, The First Affiliated Hospital of Nanjing Medical University, Nanjing, Jiangsu Province, China (HX); Department of Thoracic and Cardiovascular Surgery (DKK); and Pathology, University of Ulsan College of Medicine, Asan Medical Center, Seoul, Korea (JSS).

Extra-Abdominal Fibromatosis (Desmoid Tumor): A Rare Tumor of the Lower Extremity Arising from the Popliteal Fossa. Axial image of MRI shows a large, expansive heterogeneous soft tissue mass with contrast, closely applied to the muscular structures, and infiltration and obliteration of adjacent structures (white asteriks).Source: Ali Kaygain M. et al, Department of Cardiovascular Surgery, Erzurum Regional Training and Research Hospital, 25020 Erzurum, Turkey