SUMMARY: DWI reportedly accurately differentiates pediatric posterior fossa tumors, but anecdotal experience suggests limitations. In 3 years, medulloblastoma and JPA were differentiated by DWI alone in 23/26 cases (88%). Ependymoma (n ϭ 5) could not be reliably differentiated from medulloblastoma or JPA. A trend toward increased diffusion restriction in higher grade tumors (1/14 grade I, 7%; 9/12 grade IV, 75%) had too much overlap to predict the grade of individual cases. The overlap in ADC between tumor types appeared partly due to technical factors (in small, heterogeneous, calcific, or hemorrhagic tumors) but also likely reflected true histologic variability, given that our 3 overlap cases included a desmoplastic medulloblastoma, an anaplastic ependymoma, and a JPA with restricted diffusion in its nodule. Simple structural features (macrocystic tumor, location off midline) aided in distinguishing JPA from the other tumors in these cases.ABBREVIATIONS: ADC ϭ apparent diffusion coefficient; ADCmean ϭ mean value of ADC; ADCmin ϭ minimum value of ADC; DWI ϭ diffusion-weighted imaging; FLAIR ϭ fluid-attenuated inversion recovery; JPA ϭ juvenile pilocytic astrocytoma; WHO ϭ World Health Organization D WI might, in theory, effectively distinguish tumor types and histologic grades because higher grade tumors with more densely packed cells should have increasingly restricted diffusion (with a lower ADC).

We confirmed feasibility of knee BML scoring by new readers using interactive training and a Web-based touch-sensitive overlay system, finding high reliability and sensitivity to change. Further work will include adjustments to training materials regarding patellar scoring, and study in therapeutic trial datasets with higher burden of BML and larger changes.

Tumour volume is an important therapeutic endpoint for mouse tumour models in the evaluation of new chemotherapeutic drugs and in pre-clinical evaluation of new radioimmunotherapy pharmaceuticals. In this study, two 1 T MRI-based methods both using T1-T2 hybrid weighting, a manual method (determination of the area per slice) and a semi-automated method (using thresholding), are compared with two classical methods, the abovementioned calliper method and volumetry by water displacement after dissection of the tumour. Interoperator and intraoperator differences for both MRI-based methods were good (no differences p<0.05 using a repeated measures analysis of variance (ANOVA) test). Correlation between the different methods was excellent. No significant differences were obtained (p<0.05), except for the semi-automated method, because it automatically excludes necrotic regions from the tumour. Therefore, we conclude that both manual and semi-automated tumour volumetry in subcutaneous tumour bearing athymic mice by low-field MRI are accurate and reliable methods. The semi-automated method is especially useful for larger tumour volumes, since it accounts for necrotic areas within the tumour.

HIMRISS offers reliable BML scoring in OA, whether by conventional spreadsheet-based scoring or by a Web-based interface with interactive feedback. The new method allowed faster readings, provided a consistent training environment that helped inexperienced readers achieve reliability equivalent to that of conventional methods, and was preferred by the readers.

Haemophilic arthropathy (HA) of the elbow is an uncommon cause of elbow pain and swelling in children and adolescents.HA due to recurrent haemarthrosis is the most common musculoskeletal manifestation of haemophilia and one of the most disabling complications of this disease. Children with severe haemophilia suffer from recurrent and acute joint haemorraghe. The therapy consists of factor VIII or IX replacement infusions (treatment on demand). The aim of this therapy is to keep the deficient factor > 1% of its normal value to convert severe haemophilia into a milder form of the disorder. The importance of starting replacement therapy early has been stressed in recent literature (1-3).The aim of this study is to define the MR imaging features of HA arthropathy of the elbow at initial MR imaging. Materials and methodsA retrospective study was performed in a pediatric tertiary care centre. Institutional ethics approval was obtained.Subjects with documented HA of the elbow were identified using a radiology information system database keyword search of final radiology reports over a 10 year period. Patients with haemophilia presenting with elbow lesions in the setting of acute musculoskeletal trauma were excluded (Fig. 1-5). If the subject had undergone more than one MRI examination, only the first set of MRI images was reviewed. Twelve the first age of life and received factor substitution therapy since.The images were reviewed by two pediatric radiologists. Both reviewing radiologists were not blinded to the original reported findings but used the report only as a means to identify patients for inclusion into the study.The presence of joint effusion and synovial hypertrophy was assessed. Synovial haemosiderin deposition was considered present if blooming artefact was evident on gradient patients were identified meeting inclusion criteria for the study. The mean age was 12.2 years (range 4.1-16.6 years). All patients had been diagnosed with haemophilia within JBR-BTR, 2010, 93: 247-251. Haemophilic arthropathy of the elbow is a rare cause of elbow pain in children and adolescents. The purpose of this study is to determine the MR appearance of the spectrum of lesions found in haemophilic arthropathy of the elbow at initial MR imaging. It is important to be aware of the early changes in this entity, since early diagnosis and treatment of the disease may prevent progressive joint destruction. MR IMAGING FINDINGS OF HAEMOPHILIC ARTHROPATHY OF THE ELBOW IN CHILDREN