Diffusion-weighted MR imaging of the breast: advantages and pitfalls.

The aim of this paper is to review all clinical applications of diffusion weighted MR imaging (DWI) for breast pathology. The challenge of DWI is to obtain the best compromise between lesion detection and characterization. Technical factors affecting lesion characterization and detection are detailed including the effect of contrast administration, the choice of number of b and of b(max), the variation of diagnostic performance according to the type and the size of lesion studied.

[Diffusion-weighted MR imaging of the female pelvis]. / IRM de diffusion et pelvis féminin.

Due to technical advances (parallel imaging and new phased-array coils), diffusion-weighted MR imaging can be used to image the female pelvis. Diffusion-weighted (b=1000) images are now acquired as a complement to conventional sequences (T2W, dynamic T1W images after intravenous injection of gadolinium). Diffusion weighted imaging improves the detection of small uterine tumors and the visualization of small implants of peritoneal carcinomatosis, which could play a significant role for tumor staging. It is helpful for characterization of complex ovarian tumors: the absence of hyperintensity on b=1000 diffusion-weighted images has an excellent positive predictive value for a benign etiology. It could also be helpful to characterize endometrial lesions, to differentiate between endometrial polyp and carcinoma when hysteroscopy is not possible, and to differentiate uterine fibroid from sarcoma. Finally, diffusion-weighted imaging could be helpful to assess the response of uterine tumors to therapy and could confirm a good outcome following uterine artery embolization of uterine fibroids.

[Value of diffusion-weighted imaging in the evaluation of adnexal tumors]. / Evaluation de la séquence de diffusion pour l'étude des tumeurs annexielles.

PURPOSE: To determine the value of diffusion-weighted imaging (DWI) in the evaluation of adnexal tumors, especially to distinguish between malignant and benign tumors. Materials and methods. Fifty-four patients with pelvic tumors (32 malignant and 22 benign) were referred for MRI of the pelvis. DWI was obtained in all patients. Histological correlation was available in all cases. The signal of solid and cystic tumor components was evaluated on T2W and b=1000 DWI, and ADC values were obtained. RESULTS: T2W hypointensity or absence of hyperintense signal on b=1000 DWI sequences was suggestive of a benign tumor. Hyperintensity on b=1000 DWI sequences was strongly correlated with malignant lesions. ADC values did not appear to discriminate between malignant and benign tumors. Also, the signal intensity of cystic tumor components on DWI sequences was not helpful to distinguish between malignant and benign tumor. CONCLUSION: The evaluation of solid tumor components on DWI appears to be helpful for adnexal tumor characterization.

[Non-masslike enhancement on breast MRI: interpretation pearls]. / Le rehaussement sans masse en IRM mammaire: comment j'interprète?

The MR Breast Imaging Reporting and Data System (BI-RADS) lexicon of the American College of Radiology (ACR) includes a new lesion category defined as non-masslike enhancement. The purpose of this paper is to review the definition of this new entity, illustrate the main imaging features described in the BI-RADS lexicon and to propose a diagnostic approach based on data from the literature in order to achieve diagnosis and optimal patient management.

Accuracy of stereotactic vacuum-assisted breast biopsy with a 10-gauge hand-held system.

OBJECTIVE: The aim of this study is to evaluate the accuracy and the safety of stereotactic vacuum-assisted breast biopsy with a 10-gauge hand-held portable system. MATERIALS AND METHODS: Retrospective data review of 288 consecutive breast lesions that underwent stereotactic 10-gauge hand-held portable vacuum-assisted biopsy from October 2004 through March 2006, was performed. The mean number of core specimens and the percentage of complete radiological removal of the target lesion were analysed. ADH and DCIS under-estimation were evaluated, as were the immediate and delayed complications due to the procedure. RESULTS: The mean number of core specimens obtained per procedure was 9 (range 4-24). Complete radiological excision of the target lesion was achieved in 31.6% (91 of 288) with 91% of these lesions smaller than 10mm (mean size 7 mm; range 4-20mm). Under-estimation of ADH and DCIS was 18.2% (2 of 11) and 19.2% (9 of 47), respectively. There was no false negative result within a 3-year follow-up (from 2005 till date). Complications were mild and consisted of immediate bleeding and delayed haematomas. CONCLUSION: Breast biopsy using 10-gauge vacuum system is an accurate and safe technique for sampling non-palpable breast lesions.

[Perfusion and diffusion-weighted MR imaging in the early staging and the follow-up of patients with lung cancer]. / IRM de perfusion et de diffusion dans le bilan initial et le suivi des patients atteints de cancer bronchique.

Tissue characterization is a major and ultimate goal of imaging, whether morphological (Computed Tomography, Magnetic Resonance Imaging) or metabolic (PET-FDG-[18F]). Functional imaging, using the MRI, began several years ago with the perfusion of lung nodules and very recently with diffusion-weighted imaging applied to the lung cancer. The authors review the interest and the place of diffusion-weighted and perfusion MR imaging in the diagnosis, early staging and follow-up of patients with lung cancer.

[How to measure breast density?]. / Comment mesurer la densité mammaire?

The relation between breast tissue density and cancer risk is well known. Early quantification techniques were based on subjective visual assessment. Quantitative techniques were then developed using planimetric measurements, surface area calculations or volumetric measurements. More recently, digital mammography should allow objective computer-based density measurements using mathematical models.

[Virtual pleuroscopy of diaphragmatic pleura: myth or reality?]. / Pleuroscopie virtuelle de la plèvre diaphragmatique: mythe ou réalité ?

PURPOSE: Evaluate the feasibility of the virtual pleuroscopy (VP) in the detection of the pleural plaques. METHOD AND MATERIALS: Twenty consecutive patients, having asbestos exposure, explored by unenhanced multidetector CT-scan (Siemens, Sensation 16). The imaging parameters were as follows: beam width, 12 mm; beam pitch, 1; and reconstruction thickness, 1mm every 0.8mm at 120 kV and 180 mA. The image display used a surface-rendering algorithm and produced perspective red-scale images with a matrix of 512 x 512. Each VP image simulated a coned-down view, with a variable cone angle to explore the diaphragmatic pleura. The camera was placed 1 to 2 cm above the diaphragmatic dome. Four views are studied by diaphragm: crâniocaudal, lateral tangential, anterior and posterior. The observed virtual pleura aspect was classified in 5 groups (gr): gr 1: Rib band, gr 2: lobulated pleural thickening, gr 3: spicular, gr 4: plaques and gr 5: nodules. The results were compared to the other MDCT images using multiplanar reformatting. RESULTS: The visualization of each diaphragm was optimal (35/40; 87.5%), limited (3/40; round atelectasis and asbestosis) or impossible (2/40; asbestosis). The classifications of the studied 38 diaphragmatic pleura were: gr 1 (n=15), gr 2 (n=5), gr 3 (n=11), gr 4 (n=7), gr 5 (n=0). The MDCT analysis showed normal pleura for both gr 1 and gr 2, a confirmed or beginning of fibrosis for gr 3 and confirmed the presence of pleural plaques on the diaphragmatic pleura in all cases of gr 4. CONCLUSION: The virtual pleuroscopy is a reality. It is a feasible technique. Other studies are necessary to confirm these preliminary results.

[Imaging of chronic pelvis pain]. / Imagerie de la douleur pelvienne chronique.

This is a review of different diseases implicated in chronic pelvic pain (endometriosis, adenomyosis, pelvic varices, and pelvic chronic inflammatory disease) assessed by different imaging modalities (US, CT, MRI).

[Persistent sciatic artery: possible false negative imaging]. / Artère sciatique persistante: possibles faux-négatifs de l'imagerie.

Persistent sciatic artery is a rare congenital malformation due to the lack of regression of the dorsal arterial axis of the embryo that can be revealed by serious complications. We report a case of bilateral persistent sciatic artery revealed by subacute distal ischemia. This case illustrates the possibility of false negative imaging and the importance of ruling out this diagnosis in case of recurrent and apparently idiopathic distal embolism.

Fatal hemorrhagic complication following endovascular treatment of a cerebral arteriovenous malformation. Case report and review of the literature.

Evaluation of the natural history of brain Arteriovenous Malformations (AVMs) including its morbidity and mortality is a crucial point in the management of patients having a cerebral AVM. The risks associated with the AVM natural history, especially regarding the occurrence of an hemorrhage, have to be compared to the risks due to the therapeutic approach. In the literature, the risk of annual bleeding of an AVM is estimated from 2 to 4%. Morbidity from AVM rupture is estimated from 13% to 50% with a risk of mortality reported from 3 to 30%. Endovascular treatment is an efficient tool in the therapy of these lesions. However, AVM embolization remains a difficult procedure. Complications of the endovascular treatment must be evaluated in relation to the potential risk associated to the AVM natural history. After AVM endovascular treatment, morbidity with permanent neurological deficit is reported in 0.4% to 12.5% of patients and mortality in 0.4% to 7.5%. In more recent reports, after brain AVM embolization, a permanent neurological deficit is estimated to occur in 9% of patients and death in 2%. Hemorrhage appears the most frequent and serious complication in the endovascular treatment of a brain AVM. We report a case of fatal hemorrhagic complication following endovascular treatment of a cerebral AVM in a 20 year old patient. This case contributes to remind that embolization, even in specialized centers with experience in the management of this pathology, can be followed by a poor and even fatal outcome. In most cases, the treatment is performed in order to protect the patient of a potential risk. Consequently, the complication of the embolization must always be carefully considered and discussed between the medical team, the patient and its family for planning the AVM endovascular treatment.

[Imaging of salivary lithiasis]. / Imagerie des lithiases salivaires.

Lithiasis is the most common disease of salivary glands after mumps. The purpose of this review is to analyze the respective role of the different available imaging techniques for the diagnosis of lithiasis and related complications since the treatment of salivary lithiasis has evolved with the emergence of minimally invasive and non surgical techniques. In spite of its limitations, US represents an excellent first line imaging technique because it is non-invasive and widely available. Non contrast helical CT with multiplanar reconstructions seems to be the gold standard for the diagnosis of lithiasis, especially when small and poorly calcified since these may not be visible on standard radiographs. CT allows accurate characterization of the number and position of lithiasis. MR Sialography is increasingly replacing the more invasive conventional sialography for the non invasive visualization of the ductal system of major salivary glands even though conventional sialography has a higher spatial resolution.

[Value of sonography and MR imaging for the evaluation of deep pelvic endometriosis]. / Valeurs diagnostiques de l'echographie et de l'IRM pour l'evaluation de l'endométriose pelvienne profonde.

Deep pelvic endometriosis may involve the uterosacral ligaments, cul-de-sac of Douglas, vagina, rectum, and occasionally the bladder. Evaluation by physical examination is difficult, and imaging techniques are needed to evaluate the location and extent of endometriosis. In this review, we review the transvaginal and transrectal sonographic and MR imaging features suggestive of deep pelvic endometriosis and their diagnostic value.

Role of the healthy hemisphere in recovery after resection of the supplementary motor area.

OBJECTIVE: To determine the compensatory mechanisms involved in the recovery of motor function following surgical lesions of the supplementary motor area (SMA) and their relation to the clinical characteristics of recovery. SUBJECTS AND METHODS: Twelve patients were referred for surgery of low-grade gliomas located in the SMA, and compared to eight healthy controls using fMRI before and after surgery during self-paced movements of both hands, successively. Magnitude and volume of activation within regions of interest (primary sensorimotor cortex, premotor cortex, SMA, preSMA, and parietal lobes) were compared and tested for correlation with anatomic characteristics of the tumor and resection, and clinical data. RESULTS: Tumor growth induced preoperative underactivity in the adjacent SMA and overactivity in the opposite SMA. Postoperative recovery was associated with recruitment of a premotor network located in the healthy hemisphere including the SMA and the lateral premotor cortex. Postoperative premotor recruitment in the healthy hemisphere increased with the percentage of resection of preoperative SMA activation. Shortened onset and duration of recovery was associated with increased preoperative changes in activation levels. CONCLUSIONS: These findings suggest a dysfunction of the SMA ipsilateral to the tumor, partially compensated by a recruitment of the contralesional SMA which correlated with shortened postoperative recovery. SMA resection was compensated by the recruitment of a medial and lateral premotor circuitry in the healthy hemisphere.

Proliferative myositis in a patient with AIDS.

We report a case of proliferative myositis in the right biceps of a 56-year-old man with acquired immune deficiency syndrome (AIDS). Imaging methods included sonography, computed tomography and magnetic resonance imaging. The diagnosis was made by a core-cut biopsy and fine needle aspiration biopsy with immunohistochemical analysis. The lesion disappeared after 2 months without treatment. It is particularly important to determine whether intramuscular masses arising in patients with AIDS are due to an infectious or malignant process.

Basal ganglia and supplementary motor area subtend duration perception: an fMRI study.

Brain imaging studies on duration perception usually report the activation of a network that includes the frontal and mesiofrontal cortex (supplementary motor area, SMA), parietal cortex, and subcortical areas (basal ganglia, thalamus, and cerebellum). To address the question of the specific involvement of these structures in temporal processing, we contrasted two visual discrimination tasks in which the relevant stimulus dimension was either its intensity or its duration. Eleven adults had to indicate (by pressing one of two keys) whether they thought the duration or the intensity of a light (LED) was equal to (right hand) or different from (left hand) that of a previously presented standard. In a control task, subjects had to press one of the two keys at random. A similar broad network was observed in both the duration-minus-control and intensity-minus-control comparisons. The intensity-minus-duration comparison pointed out activation in areas known to participate in cognitive operations on visual stimuli: right occipital gyrus, fusiform gyri, hippocampus, precuneus, and intraparietal sulcus. In contrast, the duration-minus-intensity comparison indicated activation of a complex network that included the basal ganglia, SMA, ventrolateral prefrontal cortex, inferior parietal cortex, and temporal cortex. These structures form several subnetworks, each possibly in charge of specific time-coding operations in humans. The SMA and basal ganglia may be implicated in the time-keeping mechanism, and the frontal-parietal areas may be involved in the attentional and mnemonic operations required for encoding and retrieving duration information.

[Intracerebral hematoma associated with reduced apparent diffusion coefficient mimicking acute stroke]. / Hématome intracérébral et baisse importante du coefficient de diffusion mimant un accident ischémique cérébral aigu.

We report the case of a 67 year old patient admitted at our institution for acute onset of left hemiplegia. MRI was done 2 h 30 after symptom onset. Diffusion weighted images showed a hyperintense lesion in the right basal ganglia region with restricted apparent diffusion coefficient (ADC=428. 10(-6) mm(2)/s), a 50% decrease in value compared to the normal left side, consistent with acute ischemia. The lesion was hyperintense and moderately heterogeneous at FLAIR imaging, best seen on echo planar T2W images, with hypointense rim consistent with magnetic susceptibility artifact. The appearance and location of the lesion suggested the possibility of hematoma, which was confirmed at CT. Interpretation of ADC values must be performed in correlation with results at imaging including sequences sensitive to magnetic susceptibility artifacts such as echo planar T2*W and T2W sequences in order to exclude the possibility of underlying hematoma.