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May 2008
Case of the Month |
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Compiled by: Hadassah Lipstein, MD
History: 45-year-old male complaining of pain and swelling, worsening over the last two days, after being kicked in the calf three weeks prior to the study
Findings:
2.0 x 4.2 x 13.6 cm fluid collection of heterogeneous signal on both T1 and T2 pulse sequences is identified within the posterior compartment, between the medial head of the gastrocnemius and the soleus muscle. There is mass effect on the muscles and associated perifascial and subcutaneous edema. Edema within the medial and lateral heads of the gastrocnemius (fig. 7: green and yellow arrows, respectively) is consistent with contusion.
Images:
Axial PD FS (fig. 1), Axial PD FS (fig. 2), Sagittal T1 (fig. 3), Sagittal T2 FS (fig. 4), Coronal FSE T1 (fig. 5), Coronal T2 FS (fig. 6), Axial PD FS (fig. 7)
Figure 1
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Figure 2
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Figure 3
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Figure 4
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Figure 5
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Figure 6
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Figure 7
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Diagnosis: Intermuscular hematoma
Discussion:
A hematoma or contained hemorrhage may develop within or between muscles following a direct or indirect injury. MRI findings include a contained mixed-signal fluid collection with both high and low signal on T1 and T2 weighted images. The signal of the hematoma is dependent upon the age. An acute hematoma of less than 48 hours will be isointense on T1 weighted images. A subacute hematoma of less than 30 days will be higher than muscle signal on both T1 and T2 weighted images. Evolving hematomas tend to be more heterogeneous with a range of signal intensity. Chronic hematomas generally have a dark signal rim secondary to hemosiderin. Complete resorption of the blood products will result in a seroma.
Hematomas often spontaneously resorb over a period of 6-8 weeks. Surgical drainage of a hematoma is sometimes necessary to prevent compartment syndrome. Increased pressure within the fascial compartment from the hematoma results in circulatory compromise with ischemia of the muscles and nerves. If left untreated this may progress to tissue necrosis. MRI findings in acute compartment syndrome include increased T2W signal, muscle hypertrophy and /or edema, and increased T1W signal representing foci of hemorrhage. Sequelae of long-standing compartment syndrome include increased T1W signal secondary to fatty infiltration, low T1W signal representing fibrosis or dystrophic calcifications, decreased muscle volume from atrophy and fascial thickening.
References:
1. Blakenbaker, DG, De Smet, AA. MR Imaging of Muscle Injuries. Applied Radiology. 2004; 14-26.
2. Stoller DW, Tirman PFJ, Bredella MA, et al (2004). Diagnostic Imaging, Orthopaedics. Salt Lake City, Utah: Amirsys.
3. Armfield, DR. Hyun-Min Kim, D. et al. Sports-Related Muscle Injury in the Lower Extremity. Clinics In Sports Medicine. 2006(25);803-842.
4. Boutin, RD, Fritz, RC, Steinbach LS. Imaging of Sports-Related Muscle Injuries. Magn Reson Imaging Clin N Am, 2003 (11); 341-371. |
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