Staging of hip avascular necrosis: is there a need for DWI?

BACKGROUND

No comprehensive study has been performed to stage avascular necrosis of the hip using diffusion-weighted imaging (DWI).

PURPOSE

To determine apparent diffusion co-efficient (ADC) alterations in hip avascular necrosis (AVN) and to determine variations of ADC values according to stages of disease.

MATERIAL AND METHODS

The study is approved by our institutional review board and local ethical committee. Written informed consent was present for each subject. Thirty-five femoral heads of 21 cases affected by AVN were included in the study. Control group consisted of both femoral heads of 10 healthy volunteers. The hips affected by AVN were staged according to Ficat and Arlet classification system from I to IV. All cases underwent to routine hip magnetic resonance imaging (MRI) and DWI performed with a single-shot fast spin echo sequence at a b value of 600 s/mm(2). The ADC values were calculated automatically by placing ROIs on AVN lesions in affected patients and both femoral heads of control group. The median ADC value obtained from femoral heads of control group and that from AVN lesions were compared by Mann-Whitney U test. The median ADC values of AVN lesions at different stages were compared by Kruskal-Wallis test.

RESULTS

The median ADC value of normal bone measured in control group was 185.5 ± 133.2 x 10(-6) mm(2)/s. The median ADC value measured in hip avascular necrosis lesions was 988.0 ± 332.7 x 10(-6) mm(2)/s. ADC values in hip AVN lesions were statistically significantly higher than normal bone marrow (P<0.01). The median ADC values of hips with avascular necrosis at stage I, II, III, IV were 817.5 ± 172.1 x 10(-6) mm(2)/s, 902.0 ± 181.0 x 10(-6) mm(2)/s, 1200.0 ± 363.2 x 10(-6) mm(2)/s and 1024.0 ± 324.0 x 10(-6) mm(2)/s, respectively. There was no statistically significant difference among AVN lesions at stages I, II, III and IV (P>0.05).

CONCLUSION

Although DWI is a promising imaging tool that provides valuable diagnostic information in hip AVN, it fails to distinguish between different stages, and therefore is of limited value.

Leontiasis ossea in a patient with hyperparathyroidism secondary to chronic renal failure

Osteitis fibrosa describes the bone changes seen in renal osteodystrophy secondary to longstanding hyperparathyroidism. We report a 19-year-old man with longstanding chronic renal failure with a severe form of osteitis fibrosa affecting the jaws and other maxillofacial bones causing bizarre facial and dental deformity in a patient-uraemic leontiasis ossea.

The value of diffusion-weighted imaging in the diagnosis of Marchiafava-Bignami disease: apropos of a case

Marchiafava-Bignami disease (MBD) is characterized by demyelination and necrosis of corpus callosum encountered in chronic alcoholic patients. Etiology is the deficiency of vitamin B complex. Magnetic resonance imaging (MRI) in MBD typically reveals focal lesions of high T2 and FLAIR signal intensity in the corpus callosum. We here present a 42-year-old male alcoholic diagnosed as MBD on the basis of MRI and diffusion-weighted imaging (DWI) features. The patient totally recovered following appropriate vitamin B complex replacement therapy, despite reduced diffusion in the initial setting. This case report emphasizes on the important role played by MRI and DWI in the early diagnosis and follow-up of this potentially fatal disease.