Correlation between tumor growth and hormonal therapy with MR signal characteristics of desmoid-type fibromatosis: A preliminary study.

PURPOSE: To evaluate the impact of hormonal therapy on MRI characteristics of desmoid-type fibromatosis on T1-weighted, T2-weighted fat-saturated and post-contrast sequences. MATERIALS AND METHODS: Nineteen patients with histologically-proven desmoid-type fibromatosis were prospectively followed up on MR imaging. Eight patients underwent hormonal therapy and 11 were only surveyed. Change in tumor size during follow-up was analyzed according to RECIST. Signal intensity on T1-weighted, T2-weighted fat-saturated and T1-weighted fat-saturated post-contrast images was graded from 0 to 5 using adjacent normal muscle as reference. Findings were compared with tumor growth and treatment option. RESULTS: There were seven men and 12 women with a mean age of 42.2±16.4 (SD) years (range: 18 - 64 years) yielding twenty-six follow-up periods: eight of tumor progression and 18 of tumor stability/regression (some tumors exhibited more than one behavior type). Hormonal therapy was associated with tumor stability or regression (P=0.0207). There was a significant reduction in enhancement among treated patients with stable/regressing disease (P=0.049). The mean variation in enhancement grade was -1.3±1.2 in these patients. All successfully treated patients presented a reduction in enhancement. Lesions with marked low enhancement or very low signal on T2-weighted images were rare in progressing lesions (0% and 13%). CONCLUSION: Hormonal therapy has an impact on desmoid-type fibromatosis signal characteristics reducing lesion enhancement.

Protocol optimization of sacroiliac joint MR Imaging at 3 Tesla: Impact of coil design and motion resistant sequences on image quality.

PURPOSE: To evaluate the impact of coil design and motion-resistant sequences on the quality of sacroiliac magnetic resonance imaging (MRI) examination in patients with spondyloarthropathy. PATIENTS AND METHODS: One hundred and twenty-one patients with suspected sacroiliitis and referred for MRI of the sacroiliac joints were retrospectively evaluated with MRI at 3-Tesla. There were 78 women and 43 men with a mean age of 36.7±11.5 (SD) years (range: 15.8-78.4 years). Conventional and motion-resistant fat-saturated fast-spin echo T2-weighted sequences were performed with two different coils. Image quality was subjectively evaluated by two independent readers (R1 and R2) using a four-point scale. Confidence in the identification of bone marrow edema pattern (BMEP) was also evaluated subjectively using a three-point scale. RESULTS: Phased array body coil yielded improved image quality compared to surface coil (14.1 to 30.4% for R1 and 14.6 to 25.7% for R2; P<0.0001). The impact of the sequence type on quality was also statistically significant (P=0.0046). BMEP was identified in 40 patients and best inter-reader agreement was obtained using the combination of phased-array body coil with motion-resistant T2-weighted sequence (kappa 0.990). The smallest number of indeterminate BMEP zones was seen on MRI set acquired with the phased-array body coil and motion-resistant T2-weighted sequence. CONCLUSION: Phased array body coil and motion-resistant T2-weighted sequences perform better than surface coil and conventional T2-weighted sequences for the evaluation of sacroiliac joints, increasing confidence in the identification of BMEP.

Wide area detector CT perfusion: can it differentiate osteoid osteomas from other lytic bone lesions?

PURPOSE: To compare the enhancement dynamics of osteoid osteomas with other benign and malignant lytic bone lesions using CT perfusion. PATIENTS AND METHODS: CT perfusion parameters of 15 patients with a final diagnosis of osteoid osteoma, 15 patients with lesions that mimic osteoid osteomas and 26 patients with other bone lytic lesions were compared. RESULTS: Enhancement curve morphology of the osteoid osteomas was significantly different from its mimickers. All osteoid osteomas had an early enhancement with a delay between nidus and arterial peak below 30 seconds. Eighty percent of the mimickers demonstrated a slow and progressive enhancement. The perfusion parameters of the other lytic bone lesions were similar to those of the osteoid osteomas in 46.1% of the patients. CONCLUSION: Early enhancement is suggestive but not pathognomonic of osteoid osteomas. Absent or delayed enhancement in similar lesions should evoke an alternative diagnosis. The same contrast enhancement dynamics of osteoid osteomas can be seen in other bone lesions, both malignant and benign.

Standard dose versus low-dose abdominal and pelvic CT: comparison between filtered back projection versus adaptive iterative dose reduction 3D.

PURPOSE: To compare the dose and image quality of a standard dose abdominal and pelvic CT with Filtered Back Projection (FBP) to low-dose CT with Adaptive Iterative Dose Reduction 3D (AIDR 3D). MATERIALS AND METHODS: We retrospectively examined the images of 21 patients in the portal phase of an abdominal and pelvic CT scan before and after implementation of AIDR 3D iterative reconstruction. The acquisition length, dose and evaluations of the image quality were compared between standard dose FBP images and low-dose images reconstructed with AIDR 3D and FBP using the Wilcoxon test. RESULTS: The mean acquisition length was similar for both CT scans. There was a significant dose reduction of 49.5% with low-dose CT compared to standard dose CT (mean DLP of 451mGy.cm versus 892mGy.cm, P<0.001). There were no differences in image quality scores between standard dose FBP and low-dose AIDR 3D images (4.6±0.6 versus 4.4±0.6 respectively, P=0.147). CONCLUSION: AIDR 3D iterative reconstruction enables a significant reduction in dose of 49.5% to be achieved with abdominal CT scan compared to FBP, whilst maintaining equivalent image quality.

CT dose optimisation and reduction in osteoarticular disease.

With an improvement in the temporal and spatial resolution, computed tomography (CT) is indicated in the evaluation of a great many osteoarticular diseases. New exploration techniques such as the dynamic CT and CT bone perfusion also provide new indications. However, CT is still an irradiating imaging technique and dose optimisation and reduction remains primordial. In this paper, the authors first present the typical doses delivered during CT in osteoarticular disease. They then discuss the different ways to optimise and reduce these doses by distinguishing the behavioural factors from the technical factors. Among the latter, the optimisation of the milliamps and kilovoltage is indispensable and should be adapted to the type of exploration and the morphotype of each individual. These technical factors also benefit from recent technological evolutions with the distribution of iterative reconstructions. In this way, the dose may be divided by two and provide an image of equal quality. With these dose optimisation and reduction techniques, it is now possible, while maintaining an excellent quality of the image, to obtain low-dose or even very low-dose acquisitions with a dose sometimes similar that of a standard X-ray assessment. Nevertheless, although these technical factors provide a major reduction in the dose delivered, behavioural factors, such as compliance with the indications, remain fundamental. Finally, the authors describe how to optimise and reduce the dose with specific applications in musculoskeletal imaging such as the dynamic CT, CT bone perfusion and dual energy CT.

[Bone marrow edema: definition, diagnostic value and prognostic value]. / L'oedème médullaire: définition, valeur diagnostique et pronostique.

Bone marrow edema is easily identified on MRI. The terminology suggests that the water content of bone marrow is increased when it is T1W hypointense and T2W hyperintense. It is a misnomer since, histologically, the abnormality does not correspond to marrow edema. The histological findings vary based on the underlying etiology and the presence of fibrosis or inflammatory infiltrate is frequent and often predominant. In France, this terminology is used routinely to describe such lesions. The term osteitis is preferred to describe these marrow signal changes in the setting of rheumatic joint diseases. The detection of bone marrow edema is important because of its diagnostic and prognostic value. It occurs in isolation and is reversible in patients with bone contusion and complex regional pain syndrome. It indicates underlying structural damage and may modify management in patients with rheumatoid arthritis or spondylarthropathies. MR scores for disease activity rely mainly on the presence of marrow edema. Finally, diffusion weighted MR allows quantification of marrow edema and could be more sensitive than conventional MRI to detect inflammation. The purpose of this article is to review the imaging features of marrow edema, review the underlying etiologies and its diagnostic and prognostic value.