MR imaging of Achilles tendon in patients with familial hyperlipidemia: comparison with plain films, physical examination, and patients with traumatic tendon lesions.
OBJECTIVE
The purpose of this study was to evaluate the MR imaging characteristics of Achilles tendons in patients at risk for tendon xanthomas because of familial hyperlipidemia and to compare these findings with those seen on plain radiographs and physical examination. We also wished to determine if MR imaging could be used to differentiate xanthomas from traumatic tendinopathy in a second group of patients who had no history of hyperlipidemia but who had a history of trauma to the Achilles tendon.


METHODS
We evaluated the MR imaging studies of 26 Achilles tendons in 13 patients with heterozygous familial hypercholesterolemia (n = 11) and type III dysbetalipoproteinemia (n = 2). The size, shape, and signal characteristics of the Achilles tendon were recorded. A tendon was considered abnormal by MR if there was high signal, a convex anterior border, or an anteroposterior measurement greater than 7 mm. Findings on plain radiographs and physical examination of the Achilles tendons were evaluated in the same group of patients. In the group of patients with hyperlipidemia, palpable abnormalities of the Achilles tendon were present in 14 of 26 tendons. Plain radiographs were interpreted as showing abnormalities in 18 of the 26 tendons. In a second group of 21 tendons in patients with no history of hyperlipidemia but with traumatic tendinopathy, studies were evaluated for the size, shape, and signal characteristics of the Achilles tendon.


RESULTS
On MR images, 24 of 26 tendons showed signal abnormalities, and 19 of 26 were enlarged. Abnormal signal was a diffuse stippled pattern with many low-signal round structures of equal size surrounded by high-signal material on all pulse sequences. Abnormal signal was seen in tendons of both normal and abnormal size. Bilateral and symmetric changes were found in all but one patient. Tendinopathy in patients without known hyperlipidemia appeared indistinguishable from tendon xanthomas in six (29%) of 21 tendons. The other tendons (71%) were distinctly different from xanthomas without a uniform stippled signal pattern.


CONCLUSIONS
MR imaging of patients with familial hyperlipidemia showed an abnormal stippled signal pattern with or without enlargement or abnormal configuration of the tendon. MR imaging is a more sensitive method than physical examination and plain films for detecting abnormalities in Achilles tendons of patients with hyperlipidemia. Although the MR signal pattern of xanthomas is often different from that of partial tendon tears, tendon degeneration, or tendinitis, a significant overlap in appearance can be observed and the MR appearance of a xanthoma is not pathognomonic.
Dussault
R G
RG
Department of Radiology, Health Sciences Center, University of Virginia, Charlottesville 22908.
Kaplan
P A
PA
Roederer
G
G
D000125:Achilles Tendon / Q000000981:diagnostic imaging / Q000293:injuries / Q000473:pathology*; D000328:Adult; D003937:Diagnosis, Differential; D005260:Female; D006801:Humans; D006938:Hyperlipoproteinemia Type II / Q000473:pathology*; D008279:Magnetic Resonance Imaging; D008297:Male; D010808:Physical Examination; D011859:Radiography; D012421:Rupture; D012680:Sensitivity and Specificity; D052256:Tendinopathy / Q000175:diagnosis; D014973:Xanthomatosis / Q000175:diagnosis*