Widespread osteonecrosis in children with leukemia revealed by whole-body MRI

Abstract

Background: Confirmation of early long-bone epiphyseal osteonecrosis in pediatric patients with leukemia allows for medical and surgical intervention before articular surface collapse. MRI detects early osteonecrosis, but multiple focused MR images are required to capture all lesions.

Questions/purposes: We determined whether whole-body MRI (WB-MRI) could (1) assist in diagnosing long-bone epiphyseal and other osteonecroses, (2) characterize articular surface involvement, and (3) detect preferential sites for osteonecrosis.

Patients and methods: We retrospectively reviewed prospectively collected data on all 11 pediatric patients newly diagnosed with leukemia who had musculoskeletal pain develop that persisted 4 weeks or more during leukemia treatment. All were screened for osteonecrosis by WB-MRI, which consisted of a one-time scan of the entire body. Osteonecrosis was defined as circumscribed lesions with a distinct rim of low signal intensity in the normally high-intensity marrow on T1-weighted images and high signal intensity in the normally low-intensity marrow on short-tau inversion recovery images.

Results: WB-MRI confirmed osteonecrosis in nine of 11 patients. All patients had multisite lesions; eight had long-bone epiphyseal lesions, which comprised 66 of 129 (51%) of all lesions. Osteonecrosis involving greater than 50% of the epiphyseal surface was present in 57% of distal femoral and proximal tibial lesions. All humeral and femoral head lesions involved more than 1/3 of the medial surface volume but were asymptomatic. No articular collapse was present. All osteonecrotic lesions were more common in the lower extremities.

Conclusions: WB-MRI confirmed early epiphyseal osteonecrosis, with quantification of articular surface involvement. Lower limbs were preferentially affected, but asymptomatic humeral head osteonecrosis was present in five of nine patients.

Level of evidence: Level IV, diagnostic study. See Instructions for Authors for a complete description of levels of evidence.

Fig. 1A–B

The classification schemes for osteonecrotic lesions for the knee area and the proximal femoral epiphysis are shown. (A) According to the MRI classification of osteonecrosis of the knee area using the method of Karimova et al. [10], the knee area is divided into eight zones and the presence or absence of an osteonecrotic lesion is recorded in each zone, including the distal femoral diaphysis (1), distal femoral metaphysis (2), medial and lateral distal femoral epiphyses (3 and 4), medial and lateral proximal tibial epiphyses (5 and 6), proximal tibial metaphysis (7), and proximal tibial diaphysis (8). Additional characteristics of lesions located in the epiphyseal zones included what percentage (≤ 25%, 25%–50%, or > 50%) of the articular surface was involved. (Published with permission from The American Journal of Roentgenology and adapted from Karimova EJ, Rai SN, Deng X, Ingle DJ, Ralph AC, Neel MD, Kaste SC. MRI of knee osteonecrosis in children with leukemia and lymphoma. Part 1. Observer agreement. AJR Am J Roentgenol. 2006;186:470–476.) (B) According to the MRI classification of osteonecrosis of the proximal femoral epiphysis using the method described by Sugano et al. [25], Type A lesions occupy the medial 1/3 or less of the weightbearing portion, Type B lesions occupy the medial 2/3 or less, and Type C lesions occupy more than 2/3 based on the central coronal section of the proximal femoral epiphyses on T1-weighted images. (Published with permission from Sugano N, Ohzono K, Masuhara K, Takaoka K, Ono K. Prognostication of osteonecrosis of the femoral head in patients with systemic lupus erythematosus by magnetic resonance imaging. Clin Orthop Relat Res. 1994;305:190–199.)

Fig. 2

A graph shows the frequency and distribution of osteonecrosis (ON) affecting other areas (nonlong-bone epiphyses) in the upper and lower extremities.

Fig. 3A–B

The feet and ankles of a 4-year-old girl with ALL, who transiently refused to walk because of severe foot pain, are shown in these images. (A) The lateral radiograph of her left ankle and hindfoot and midfoot does not show lesions suggestive of osteonecrosis. (B) WB-MRI (shown for below-the-knee lesions) performed on the same day shows multiple osteonecrotic lesions in the tibia and distinct osteonecrotic lesions in both calcanei (arrows).