Magnetic Resonance Imaging of Benign Soft …

1 Magnetic ResonanceImaging of BenignSoft Tissue Neoplasmsin AdultsEric A. Walker,MDa,b,*, Michael E. Fenton,MDc,Joel S. Salesky,MDc, Mark D. Murphey,MDb,c,dBenign soft tissue lesions outnumber their malig-nant counterparts by a factor of 100 ,2 Manyof these lesions are small and superficial and donot lead to Imaging evaluation or biopsy; soprecise estimates are unavailable. Magnetic reso-nance (MR) Imaging is the favored modality forevaluation of soft tissue tumors and tumorlikeconditions because of its superior soft tissuecontrast, multiplanar Imaging capability, and lackof radiation exposure. MR Imaging is valuable forlesion detection, diagnosis, and planning an MR Imaging study for evalua-tion of a soft tissue lesion, at least 2 orthogonalplanes should be obtained.

2 In our experience,lesions are typically best evaluated in the axialplane, and this plane is usually the most familiarto radiologists. The secondary plane of imagingfor an anterior or posterior lesion is typically thesagittal plane. Coronal sequences are optimal forevaluation of medial or lateral (T1W) and T2-weighted (T2W)sequences should be obtained because mostsoft tissue lesions have been described with theirspin echo (SE) T1W and T2W signal characteris-tics. Fast-spin echo sequences in place of SEsequences can reduce scanning time and patientmotion artifacts. Gradient echo sequences canbe useful for demonstrating hemosiderin with blooming and also are subject to artifact causedby metal, hemorrhage, and air.

3 Short tau inversionrecovery and chemical shift selective fat saturationT2W images increase sensitivity to abnormal tissuecontaining increased water content. However, inour opinion, these techniques also reduce infor-mation concerning various tissue consistenciesand should be used in the secondary, not theprimary, plane of Imaging . The smallest diagnosticfield of view is preferable when evaluating use of intravenous contrast for lesion evalu-ation is controversial but appropriate in certaincircumstances. Gadolinium contrast agents in-crease the T1W signal intensity of many soft tissuetumors, allowing distinction between tumor andmuscle or tumor and edema, but the surroundingarea of edema may enhance as well.

4 Informationabout tumor vascularity is also ,4 Com-paring precontrast and postcontrast T1W fatDisclaimer: The opinions or assertions contained herein are the private views of the authors and are not to beconstrued as official or as reflecting the views of the Departments of the Army, Navy, or of Radiology, H066, Milton S. Hershey Medical Center, 500 University Drive, Box 850,Hershey, PA 17033, USAbDepartment of Radiology and Nuclear Medicine, Uniformed Services University of the Health Sciences, 4301 Jones Bridge Road, Bethesda, MD 20814, USAcAmerican Institute for Radiologic Pathology, 1010 Wayne Avenue, Suite 320, Silver Spring, MD 20910, USAdDepartment of Radiology, Walter Reed Army Medical Center, Washington, DC, USA* Corresponding author.

5 Department of Radiology, H066, Milton S. Hershey Medical Center, 500 UniversityDrive, Box 850, Hershey, PA soft tissue tumor Benign MR Imaging soft tissue neoplasmRadiol Clin N Am 49 (2011) 1197 1217 $ see front matter 2011 Elsevier Inc. All rights sequences is useful to distinguish trueenhancement from a high T1W signal processsuch as lesion hemorrhage or a proteinaceousfluid investigators have evaluated the use ofdynamic enhancement with gadolinium to aid indifferentiating Benign from malignant soft ,5,6 High soft tissue vascularity and perfu-sion result in an increased rate of lesions usually reveal less enhancementoverall and a delayed rate of a significant overlap between the rate of en-hancement of Benign and malignant opinion and experience.

6 Dynamic enhance-ment does not obviate biopsy of the otherwiseindeterminate solid soft tissue are conflicting regarding the use oftumor margins, homogenous versus heteroge-neous signal intensity, and lesion size to distin-guish Benign from malignant lesions. The mostoptimistic report suggests the distinction can bemade in more than 90% of investi-gators note that malignant lesions can appearsmoothly marginated and homogenous and MRappearance cannot accurately separate benignand malignant ,10 14 Only a minority(5%) of soft tissue tumors are larger than 5 cm indiameter, and about 1% of Benign lesionsare ,16In general, well-defined smoothmargins, homogenous signal intensity, and smallsize are seen with Benign lesions.

7 Unless a specificdiagnosis can be determined, a lesion should beconsidered indeterminate and biopsy performed,with an appropriate biopsy path discussed withthe orthopedic oncologist or treating ,18 Lesion location is important for limiting thedifferential diagnosis. MR Imaging with its excel-lent soft tissue contrast is superior for determininglesion location. Descriptions of lesion locationinclude intramuscular, intermuscular, subcuta-neous, and intra-articular/periarticular. A multi-focal or an extensive lesion also limits diagnosticconsiderations to include angiomatous lesions,neurofibromatosis (NF), fibromatosis, lipomatosis,and myxoma (in cases of Mazabraud syndrome).

8 In contradistinction to other organ locations,metastases and lymphoma are less likely consid-erations. Specific anatomic location may also aidin diagnosis, such as elastofibroma occurringdeep to the scapular discussed in this review are includedbecause of their frequency, location, or uniqueimaging characteristics, allowing a specific diag-nosis or limited differential diagnosis. For commonbut nonspecific lesions, a reasonable differentialdiagnosis requires knowledge of lesion preva-lence, anatomic distribution, and age that predominantly affect pediatricpatients (see the article by Navarro and colleagueselsewhere in this issue for further exploration ofthis topic), malignant soft tissue tumors (see thearticle by Walker and colleagues elsewhere inthis issue for further exploration of this topic),and tumorlike conditions (see the article by Stacyand colleagues elsewhere in this issue for furtherexploration of this topic) are discussed in separatearticles within this FASCIITISN odular fasciitis (Fig.)

9 1) is a Benign soft tissuelesion composed of proliferating fibroblasts. Thelesion may grow rapidly and show high mitoticactivity, simulating a more aggressive lesion. It isthe most common tumor or tumorlike condition offibrous fasciitis typically affectspatients aged between 20 and 40 years, with nosex 22 Lesions typically present asa rapidly growing painless mass that may causemild pain or tenderness in approximately 50% upper extremity is involved in 46%of cases, particularly the volar forearm. Othercommon locations include the head/neck (20%),the trunk (18%) and the lower extremity (16%).23 The size of this lesion can vary from to 10 cm,but most (71%) are 2 cm or fas-ciitis has 3 common locations: subcutaneous,fascial, and are subcuta-neous between 3 and 10 times more frequentlythan other sites.

10 The fascial form is the secondmost common, and the least frequent is the intra-muscular type. The deeper intramuscular form isusually larger and is the most likely to be mistakenfor ,25,26 Recurrence of nodular fasciitisis rare even after partial or ossification is rarely seen T1W images, nodular fasciitishas a signal intensity similar to or slightly higherthan skeletal ,28 With T2W sequences,the condition most often has a high signal intensity(> subcutaneous fat) but may demonstrate inter-mediate signal are frequentlyhomogeneous on T1W sequences and heteroge-neous on longer repetition time (TR) lesion, as well as ancient schwannoma, is oneof the few Benign lesions that may demonstratecentral necrosis, which may contribute to enhancement waspresent in all cases in a series of 8 patients witha diffuse enhancement pattern in 63% of casesand peripheral enhancement in approximately25%.