A. Yusuf Oner

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/mm2. 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 mm2/s. The median ADC value measured in hip avascular necrosis lesions was 988.0 ± 332.7 x 10−6 mm2/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 mm2/s, 902.0 ± 181.0 x 10−6 mm2/s, 1200.0 ± 363.2 x 10−6 mm2/s and 1024.0 ± 324.0 x 10−6 mm2/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.

T2-weighted vs. intrathecal contrast-enhanced MR cisternography in the evaluation of CSF rhinorrhea

Background Endoscopic surgical approach is being more widely used in the treatment of cerebrospinal fluid (CSF) rhinorrhea. Accurate localization of CSF fistulas prior to surgery is essential in increasing the success of dural repair and in decreasing negative or recurrent explorations. Purpose To evaluate and compare intrathecal contrast medium-enhanced magnetic resonance cisternography (CEMRC) with T2-weighted MR cisternography (T2MRC) in identifying the presence and site of CSF rhinorrhea. Material and Methods Sixty patients with suspected CSF rhinorrhea underwent MR cisternography including intrathecally enhanced fat-suppressed T1WI in three orthogonal planes and T2WI in the coronal plane. Both set of images were reviewed by two blinded radiologists for the presence and location of CSF leakage. Imaging data were compared with surgical findings and/or beta-2 transferrin testing. Results With surgery proven CSF leakage in 20 instances as reference, CEMRC detected 18 (90%), whereas T2MRC reported only 13 (65%) correctly. Overall, sensitivity, specificity, positive predictive value, and negative predictive value in detecting CSF fistulas were 92%, 80%, 76%, and 93% for CEMRC, and 56%, 77%, 64%, and 71% for T2MRC, respectively. Conclusion The minimally invasive CEMRC is an effective method with higher sensitivity and specificity than T2MRC in the evaluation of CSF fistulas.

Pyogenic spinal infections.

Spinal infections are a spectrum of disease comprising spondylitis, diskitis, spondylodiskitis, pyogenic facet arthropathy, epidural infections, meningitis, polyradiculopathy, and myelitis. Inflammation can be caused by pyogenic, granulomatous, autoimmune, idiopathic, and iatrogenic conditions. In an era of immune suppression, tuberculosis, and HIV epidemic, together with worldwide socioeconomic fluctuations, spinal infections are increasing. Despite advanced diagnostic technology, diagnosis of this entity and differentiation from degenerative disease, noninfective inflammatory lesions, and spinal neoplasms are difficult. Radiological evaluations play an important role, with contrast-enhanced MR imaging the modality of choice in diagnosis, evaluation, treatment planning, interventional treatment, and treatment monitoring of spinal infections.

Presurgical evaluation of mesial temporal lobe epilepsy with multiple advanced MR techniques at 3T

BACKGROUND AND PURPOSE Accurate localization of the epileptogenic zone is essential for successful surgical treatment of mesial temporal lobe epilepsy (MTLE). The aim of this study was to analyze and compare the hippocampal volumetry (HV), MR spectroscopy (MRS), Dynamic susceptibility contrast (DSC) and pulsed arterial spin labeling (pASL) perfusion techniques in a large sample size of refractory MTLE patients. MATERIALS AND METHODS Forty-two patients with medically refractory MTLE who underwent preoperative evaluation and eleven normal controls were studied. Pathologic and control hippocampi were compared in terms of hippocampal volume, metabolite ratios and relative hippocampal perfusion values. By using cut-off points and asymmetry indexes, percentages of performance indicators for each technique were calculated in groups of MR (+), MR (-) and bilateral MTLE. RESULTS For all techniques, a statistically significant difference was found between the pathologic and control hippocampus groups (P<0.001). Also, all of them except HV had diagnostic value in groups of MR (-) and bilateral MTLE. CONCLUSION HV, MRS, DSC and pASL have achieved comparable performance and each of them provides important information about the lateralization of epileptogenic focus. Among those, pASL and MRS may easily be used as an adjunct to conventional MR.

pASL versus DSC perfusion MRI in lateralizing temporal lobe epilepsy.

Background Accurate lateralization of the epileptogenic focus in temporal lobe epilepsy (TLE) is crucial. Pulsed arterial spin labeling (pASL) has the capability of quantifying local relative cerebral blood flow (rCBF) by measuring the inflow of electromagnetically labeled arterial blood into the target area, and can be used in the presurgical workup of refractory TLE. Purpose To evaluate pASL in detecting mesial temporal lobe (mTL) perfusion asymmetry for the lateralization of the epileptogenic focus in patients with refractory TLE and to compare it with dynamic susceptibility contrast enhanced (DSC) magnetic resonance imaging (MRI) technique. Material and Methods This study was approved by the local ethical committee, and written informed consent was obtained in each patient. Thirty-six patients with medically refractory TLE and 11 healthy volunteer was enrolled in this study. Following brain MRI, pASL and DSC perfusion were performed in all subjects at 3T. rCBF measurements with two different perfusion MRI technique were compared between the patient and healthy volunteers. Lateralization based on perfusion asymmetry index (AI) were also evaluated and compared with clinical lateralization. Results rCBF ratios measured in healthy volunteers by two different perfusion technique did not show any statistically significant difference. In TLE patients rCBF ratio of the ipsilateral (affected) side was found to be significantly lower than the contralateral (unaffected) side with both technique. The AI in the patient group was 8.86 ± 3.88 with pASL and 8.39 ± 4.06 with DSC. Correlation coefficient between clinical laterality and perfusion AI were 0.86 for pASL and 0.83 for DSC. Conclusion pASL can successfully detect interictal asymmetry in patients with TLE and can readily be combined with routine structural assessment for lateralization, providing an alternative to DSC perfusion.

Imaging findings of Nasu–Hakola disease: a case report

Nasu-Hakola disease (NHD), also known as polycystic lipomembranous osteodysplasia and sclerosing leukoencephalopathy, is a rare and fatal hereditary disease with less than 200 cases reported in the literature [Madry H, Prudlo J, Grgic A, Freyschmidt J. Nasu-Hakola disease (PLOSL): report of five cases and review of the literature. Clin Orthop Relat Res 2007;454:262-269]. This progressive disease is characterized by multiple cystic bone lesions, complicated with pathologic fractures and progressive dementia. Here in this article we report the imaging findings including magnetic resonance imaging of a newly diagnosed NHD case, with emphasis on the awareness of the radiologist for prompt recognition of this rare entity.