Morton neuroma: MR imaging in prone, supine, and upright weight-bearing body positions.
OBJECTIVE
To assess the effect of prone, supine, and upright weight-bearing body positions on visibility, position, shape, and size of Morton neuroma during magnetic resonance (MR) imaging.


METHODS
Eighteen patients with 20 Morton neuromas underwent MR imaging of the forefoot in prone (plantar flexion of the foot), supine (dorsiflexion of the foot), and upright weight-bearing positions. Visibility (3 = good, 2 = moderate, 1 = poor), position relative to the metatarsal bone, shape, and transverse diameter of Morton neuroma were assessed on transverse T1-weighted MR images. Associations between different body positions and variables of interest were calculated with Wilcoxon signed rank test, chi2 test, and paired Student t test.


RESULTS
In the prone position, visibility of all 20 Morton neuromas was rated with a score of 3; visibility in the supine and weight-bearing positions was inferior (mean score, 2.4). All 20 (100%) Morton neuromas changed their position relative to the metatarsal bone between prone and supine and between prone and weight-bearing positions. When compared with the prone position, there was a difference in the shape of all 20 Morton neuromas in the weight-bearing position (P <.001). Between prone (mean transverse diameter of Morton neuroma, 8 mm) and supine (mean transverse diameter of Morton neuroma, 6 mm) positions, the transverse diameter of Morton neuroma significantly decreased by 2 mm (P =.03); between prone and weight-bearing positions, the decrease of the mean transverse diameter was also significant (difference, 2 mm; P =.03).


CONCLUSIONS
Morton neuroma appears significantly different during MR imaging in prone, supine, or weight-bearing positions. The transverse diameter of Morton neuroma is significantly larger on images obtained in the prone position than it is on images obtained in the supine and upright weight-bearing positions. Visibility of Morton neuroma is best on MR images obtained in the prone position.
Weishaupt
Dominik
D
Institute of Diagnostic Radiology, University Hospital, Rämistrasse 100, CH-8091 Zurich, Switzerland. dominik.weishaupt@dmr.usz.ch
Treiber
Karl
K
Kundert
Hans-Peter
HP
Zollinger
Hans
H
Vienne
Patrice
P
Hodler
Juerg
J
Willmann
Jurgen K
JK
Marincek
Borut
B
Zanetti
Marco
M
D000328:Adult; D000368:Aged; D016009:Chi-Square Distribution; D005260:Female; D005534:Foot Diseases / Q000175:diagnosis*; D006801:Humans; D008279:Magnetic Resonance Imaging / Q000379:methods*; D008297:Male; D008875:Middle Aged; D009463:Neuroma / Q000175:diagnosis*; D016684:Prone Position; D018709:Statistics, Nonparametric; D016683:Supine Position; D016474:Weight-Bearing