Acute retroperitoneal hemorrhage complicating a xanthogranulomatous pyelonephritis.
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Adult↗
Biomedical subjects
Alain Rahmouni
Publications and source records attributed to Alain Rahmouni.
Adenocarcinomas of unknown primary (ACUP) of the mediastinum mimicking lymphoma: CT findings at diagnosis and follow-up.
OBJECTIVE: To describe the computed tomography (CT) features at diagnosis and after treatment of adenocarcinoma of unknown primary (ACUP) mimicking lymphoma of the mediastinum. METHODS: Fifteen patients with pathologically proven ACUP and with primarily mediastinal involvement were initially referred to the Hematologic Department of our institution with a suspected diagnosis of lymphoma, and accounted for our study population. Presenting symptoms and baseline biological values were analyzed. All thoraco-abdominal CT studies were reviewed for the location and size of the mediastinal involvement and associated findings. Follow-up chest CT was performed in 14 patients after radiotherapy, chemotherapy or surgical treatment. RESULTS: The most frequent CT feature was a large anterior and middle mediastinal mass (67%), with no calcification. Associated findings included the presence of lung nodules (40%), compression of large mediastinal vessels (33%) and pleural effusion (27%). Follow-up CT, performed in 14 cases, suggested partial or complete responses in 7 patients (50%) 4 weeks after the treatment onset. CONCLUSIONS: Mediastinal ACUP is a differential diagnosis of large mediastinal masses and is frequently associated with lung nodules and mediastinal vascular compression.
Adenocarcinoma↗
Lymph node imaging: basic principles.
Lymph nodes are involved in a wide variety of diseases, particularly in cancer. In the latter, precise nodal staging is essential to guide therapeutic options and to determine prognosis. For long, imaging of the lymphatic system has been limited to lymph vessel,especially via the exclusive use of conventional lymphography, at the expense of invasive procedures and patient's discomfort. Three main technical advances, however, have recently completed the clinical armamentarium for lymph node imaging: first, the refinement of cross sectional imaging, i.e. CT and MRI, combined or not with dedicated contrast agents, has progressively replaced conventional lymphography in oncology situations; second, the development of intra-operative sentinel node mapping has profoundly modified the diagnostic and therapeutic procedures in several cancer situations, mostly melanoma and breast cancer; finally, the increased availability of functional imaging, especially through the use of FDG-PET, has greatly contributed to the accuracy improvement of nodal metastases identification. The aim of this review will thus be to briefly review the anatomy and physiology of the lymphatic systems and to overview the basic principles of up-to-date lymph node imaging.
Contrast Media↗
Value of [18F]fluorodeoxyglucose-positron emission tomography in managing patients with aggressive non-Hodgkin's lymphoma.
An increased glucose metabolic rate is observed with various degrees of intensity in different subtypes of aggressive lymphomas. [(18)F]Fluorodeoxyglucose (FDG)-positron emission tomography (PET; FDG-PET) allows functional imaging of this phenomenon through 3-dimensional tomographic slices, which are now easily fused with computed tomography (CT) images. [(18)F]Fluorodeoxyglucose-PET staging appears superior to conventional staging modalities for detecting nodal and extranodal lymphoma. When performed after first-line chemotherapy, FDG-PET is more efficient than CT and conventional diagnostic methods to predict the disease outcome. Some studies have reported that the relapse rate is 100% in patients with positive PET findings after treatment and 17% in patients with negative PET findings. This imaging modality can also assess early response after 1-2 cycles of chemotherapy, thus identifying responders from patients whose cancer will fail to respond to first-line therapy or will relapse shortly after having exhibited a partial or complete remission. [(18)F]Fluorodeoxyglucose-PET also seems useful for an accurate selection of patients who will benefit from highly intensive treatment.
Fluorodeoxyglucose F18↗
Quantitative CT analysis for assessing response in lymphoma (Cheson's criteria).
Standardized CT-based criteria used for lymphoma staging and follow-up and the current role of FDG-PET are reviewed. The current CT-based International Workshop Criteria (IWC) still have the main advantage of representing standardized criteria allowing comparability of clinical trials in patients with lymphoma. However, functional imaging with integrated IWC and FDG-PET provide more accurate response assessment, and challenge the current paradigm. Although integration of FDG-PET in IWC requires validation in a prospective trial with a large number of patients, new long-term clinical and therapeutic trials probably need to be designed using these new and hopefully standardized functional criteria. This potentially could allow a more risk-adapted approach to the treatment of aggressive lymphoma: intensive (reinforced) therapies for non-responders vs. less intensive therapies for good responders with the main goal of improved clinical outcome.
Fluorodeoxyglucose F18↗
MRI and PET in monitoring response in lymphoma.
The potential of FDG-PET and MRI in monitoring response to treatment in lymphoma is reviewed. Both FDG-PET and MRI can provide whole body imaging. Both also share the advantage of combining functional and anatomical information. At present, hybrid FDG-PET and MDCT is the best technique for monitoring response to treatment, especially early response to treatment. Early assessment of response to treatment has the potential to tailor therapy. MR imaging is useful especially in assessing bone marrow and central nervous system involvement.
Contrast Media↗
[18F]fluoro-2-deoxy-D-glucose positron emission tomography (FDG-PET) in aggressive lymphoma: an early prognostic tool for predicting patient outcome.
Assessment of early therapeutic response using metabolic imaging is potentially useful to determine prognosis in aggressive lymphoma. Between January 2000 and January 2004, 90 patients with newly diagnosed aggressive lymphoma (median age 53 years, 94% diffuse large B-cell) were prospectively explored with [18F]fluoro-2-deoxy-D-glucose positron emission tomography (FDG-PET) prior to induction chemotherapy, after 2 cycles ("early PET"), and after induction completion. Therapeutic response was evaluated using conventional diagnostic methods at 4 cycles. Induction treatment with an anthracycline-containing regimen was administered to all patients, associated with rituximab in 41%. According to the International Prognostic Index (IPI), 37 patients and 53 patients belonged to the lower- and higher-risk groups, respectively. At midinduction, "early PET" was considered negative in 54 patients and positive in 36. After completion of induction, 83% of PET-negative patients achieved complete remission compared with only 58% of PET-positive patients. Outcome differed significantly between PET-negative and PET-positive groups; the 2-year estimates of event-free survival reached 82% and 43%, respectively (P < .001), and the 2-year estimates of overall survival reached 90% and 61%, respectively (P = .006). Predictive value of "early PET" was observed in both the lower-risk and higher-risk groups, indicating prognostic independence from the IPI. Therefore, FDG-PET should be an early guide to first-line strategies in aggressive lymphoma.
Adolescent↗
Assessment of critical limb ischemia in patients with diabetes: comparison of MR angiography and digital subtraction angiography.
OBJECTIVE: The purpose of our study was to evaluate the diagnostic accuracy of hybrid MR angiography by comparison with digital subtraction angiography (DSA) in diabetic patients with critical limb ischemia. SUBJECTS AND METHODS: Thirty-one patients prospectively underwent both hybrid MR angiography and DSA. The hybrid MR angiography study consisted of high-resolution MR angiography of a single calf and foot using a contrast-enhanced 3D gradient-echo volumetric interpolated breath-hold examination with surface coils, followed by three-station bolus chase MR angiography with a dedicated peripheral vascular coil. Two blinded reviewers separately analyzed maximum-intensity-projection hybrid MR angiograms and DSA images. The peripheral vessels were divided into 10 anatomic segments for review. The status of each segment was graded as normal, stenosis less than 50% in diameter, stenosis greater than 50%, or occluded. The sensitivity and specificity of hybrid MR angiography were determined using DSA as the gold standard. Treatment options were considered separately from the results of each examination. RESULTS: Among 310 analyzed segments, the sensitivities of hybrid MR angiography for stenosis and occlusion were, respectively, 95% and 95% for reviewer 1 and 96% and 90% for reviewer 2. The specificities of hybrid MR angiography for stenosis and occlusion were, respectively, 98% and 98% for reviewer 1 and 98% and 99% for reviewer 2. In 25 patients (81%), the quality of bolus chase MR angiography images was insufficient to assess runoff arteries. All treatments proposed on the basis of DSA findings were endorsed by hybrid MR angiography findings. Eleven more treatments were formulated on the basis of hybrid MR angiography findings. Of these, four were due to overestimation of stenosis on MR angiography and seven were due to the detection of patent infrageniculate arteries on hybrid MR angiography that were not detected on DSA. CONCLUSION: Hybrid MR angiography depicts runoff arteries not seen on DSA. Hybrid MR angiography may be useful for treatment planning in selected diabetic patients with critical limb ischemia.
Adult↗
MR demonstration of septal involvement in arrhythmogenic right ventricular dysplasia.
Arrhythmogenic right ventricular dysplasia (ARVD) is a heart muscle disease of unknown origin. Although MR imaging is regarded as the best technique for the demonstration of functional and structural abnormalities in ARVD, fat deposits in the interventricular septum have never been documented on MR imaging. We report the case of interventricular septal fatty deposition demonstrated by fat-suppressed MR imaging in a 48-year-old man.
Arrhythmogenic Right Ventricular Dysplasia↗
Comparison of in vitro and in vivo MRI of the spine using parallel imaging.
OBJECTIVE: The purpose of this study was to compare the image quality of two parallel-imaging methods applied to standard turbo spin-echo T2-weighted imaging of the lumbar spine. MATERIALS AND METHODS: Phantom imaging and lumbar spine studies of 15 healthy subjects were performed using T2-weighted turbo spin-echo sequences obtained with and without parallel imaging (generalized autocalibrating partially parallel acquisition [GRAPPA] and modified sensitive encoding [mSENSE]) on a 1.5-T magnet. The signal-to-noise ratio (SNR) and uniformity were measured in the phantom, and SNR and signal difference-noise ratio were evaluated in cerebrospinal fluid, vertebral bodies, and subcutaneous fat of the volunteers, using both techniques sequentially. Aliasing artifacts on GRAPPA and mSENSE images were visually evaluated. SNRs were compared using the Student's paired t test, with p values less than 0.05 considered significant. RESULTS: In the phantom study, when the same number of coil elements were used (n = 3), SNR and uniformity values obtained with standard T2-weighted turbo spin-echo sequences were higher than those obtained with parallel sequences. The GRAPPA SNR obtained with three coil elements was higher than the standard T2-weighted SNR obtained with one coil element. Similar findings were noted regarding uniformity. In the lumbar spine, GRAPPA SNR values for fat, cerebrospinal fluid, and vertebral bodies were significantly higher than mSENSE SNR values, with a p value less than 0.01, but were not significantly different from T2-weighted turbo spin-echo SNR values. GRAPPA signal difference-noise ratio values were significantly higher than mSENSE signal difference-noise ratio values, with a p value less than 0.01, but were not significantly different from T2-weighted turbo spin-echo signal difference-noise ratio values. GRAPPA produced fewer aliasing artifacts than mSENSE. CONCLUSION: In spine MRI, GRAPPA may be used to reduce scanning time and yields a higher SNR than mSENSE without any increase in aliasing artifacts and with an SNR similar to that obtained with standard T2-weighted turbo spin-echo.
Artifacts↗
Simultaneous bilateral breast and high-resolution axillary MRI of patients with breast cancer: preliminary results.
OBJECTIVE: The aims of this study were to develop a standardized one-step procedure for simultaneous high-resolution MRI of the axilla and bilateral breast MRI and to identify nodal features suggestive of metastatic involvement. SUBJECTS AND METHODS. We studied 16 women undergoing axillary lymph node dissection after combined bilateral breast MRI and high-resolution MRI of the axilla with a maximum in-plane resolution of 0.6 x 0.4 mm. MRI was performed using a standard double breast coil and a 15-cm round flexible surface coil adapted to the axilla. High-resolution axillary sequences, including inversion recovery T2- and spin-echo T1-weighted sequences, were performed before and after gadolinium chelates bolus injection. Axillary image analysis focused on nodal morphology including size, contour regularity, cortex and hilar appearance, signal intensity, and enhancement parameters. Axillary MRI findings were compared with the final pathogic results from axillary lymph node dissection in all patients. Patients were divided into groups according to the final pathologic axillary status. Differences in MRI lymph node features across the groups were tested using a t test for quantitative data and the chisquare test or Fisher's exact test for binary data. RESULTS: The features of the axilla on high-resolution MRI that best discriminated between patients with positive pathologic findings and those with negative pathologic findings were the presence of nodes with irregular contours (p < 10(-4)), high signal intensity on T2 sequences (p < 10(-3)), marked gadolinium enhancement (p < 10(-3)), and round hila and abnormal cortexes (p < 0.05). CONCLUSION: Breast tissue and axillary lymph nodes both can be analyzed on MRI in a one-step process using a bilateral breast coil combined with a surface coil. Morphologic features observed on high-resolution MRI of the axilla can improve the identification of metastatic nodes.
Adult↗
Normal spinal bone marrow in adults: dynamic gadolinium-enhanced MR imaging.
PURPOSE: To determine the patterns of dynamic enhancement of normal spinal bone marrow in adults at gadolinium-enhanced magnetic resonance (MR) imaging and the changes that occur with aging. MATERIALS AND METHODS: Dynamic contrast material-enhanced MR imaging of the thoracolumbar spine was performed in 71 patients. The maximum percentage of enhancement (Emax), enhancement slope, and enhancement washout were determined from bone marrow enhancement time curves (ETCs). The bone marrow signal intensity on T1-weighted spin-echo MR images was qualitatively classified into three grade categories. Quantitative ETC values were correlated with patient age and bone marrow fat content grade. Statistical analysis included mean t test comparison, analysis of variance, and regression analysis of the correlations between age and quantitative MR parameters. RESULTS: Emax, slope, and washout varied widely among the patients. Emax values were obtained within 1 minute after contrast material injection and ranged from 0% to 430%. Emax values were significantly higher in patients younger than 40 years than in those aged 40 years or older (P <.001). These values decreased with increasing age in a logarithmic relationship (r = 0.71). Emax values decreased as fat content increased, but some overlap among the fat content grades was noted. Analysis of variance revealed that Emax was significantly related to age (younger than 40 years vs 40 years or older) (P <.001) and fat content grade (P <.001) but not significantly related to sex. CONCLUSION: Dynamic contrast-enhanced MR imaging patterns of normal spinal bone marrow are dependent mainly on patient age and fat content.
Adolescent↗
Bone marrow with diffuse tumor infiltration in patients with lymphoproliferative diseases: dynamic gadolinium-enhanced MR imaging.
PURPOSE: To evaluate gadolinium enhancement of bone marrow in patients with lymphoproliferative diseases and diffuse bone marrow involvement. MATERIALS AND METHODS: Dynamic contrast material-enhanced magnetic resonance (MR) imaging of the thoracolumbar spine was performed in 42 patients with histologically proved diffuse bone marrow involvement and newly diagnosed myeloma (n = 31), non-Hodgkin lymphoma (n = 8), or Hodgkin disease (n = 3). The maximum percentage of enhancement (Emax), enhancement slope, and enhancement washout were determined from enhancement time curves (ETCs). A three-grade system for scoring bone marrow involvement was based on the percentage of neoplastic cells in bone marrow samples. Quantitative ETC values for the 42 patients were compared with ETC values for healthy subjects and with grades of bone marrow involvement by using mean t test comparisons. Receiver operating characteristic (ROC) analysis was conducted by comparing Emax values between patients with and those without bone marrow involvement. Baseline and follow-up MR imaging findings were compared in nine patients. RESULTS: Significant differences in Emax (P <.001), slope (P <.001), and washout (P =.005) were found between subjects with normal bone marrow and patients with diffuse bone marrow involvement. ROC analysis results showed Emax values to have a diagnostic accuracy of 99%. Emax, slope, and washout values increased with increasing bone marrow involvement grade. The mean Emax increased from 339% to 737%. Contrast enhancement decreased after treatment in all six patients who responded to treatment but not in two of three patients who did not respond to treatment. CONCLUSION: Dynamic contrast-enhanced MR images can demonstrate increased bone marrow enhancement in patients with lymphoproliferative diseases and marrow involvement.
Adult↗
Magnetic resonance imaging of targeted catheter-based implantation of myogenic precursor cells into infarcted left ventricular myocardium.
OBJECTIVES: This study was designed to test the hypothesis that myocardial implantation of myogenic precursor cells (MPC) loaded with iron oxide can be reliably detected in vivo by cardiac magnetic resonance imaging (MRI). BACKGROUND: In vivo imaging of targeted catheter-based implantation of MPC into infarcted left ventricular (LV) myocardium is unavailable. METHODS: The study was conducted in seven farm pigs (four with anterior myocardial infarction), in which autologous MPC were injected through a percutaneous catheter allowing for LV electromechanical mapping and guided micro-injections into normal and infarcted myocardium. Cardiac MRI was used to detect implanted MPC previously loaded with iron oxide nanoparticles. RESULTS: Magnetic resonance imaging data were compared with LV electromechanical mapping and cross-registered pathology. All 9 injections into normal and 12 injections into locally damaged myocardium were detected on T2-weighted spin echo and inversion-recovery true-fisp MRI (low signal areas) with good anatomical concordance with sites of implantation on electromechanical maps. All sites of injection were confirmed on pathology that showed in all infarct animals iron-loaded MPC at the center and periphery of the infarct as expected from MRI. CONCLUSIONS: Targeted catheter-based implantation of iron-loaded MPC into locally infarcted LV myocardium is accurate and can be reliably demonstrated in vivo by cardiac MRI. The ability to identify noninvasively intramyocardial cell implantation may be determinant for future experimental studies designed to analyze subsequent effects of such therapy on detailed segmental LV function.
Animals↗
Endoventricular porcine autologous myoblast transplantation can be successfully achieved with minor mechanical cell damage.
OBJECTIVE: Transplantation of skeletal myogenic precursor cells (mpc) into the myocardium using a non-surgical procedure. METHODS: Closed-chest mpc transplantation was assessed in pigs using the NOGA-Biosense device allowing both electromechanical mapping of the left ventricle (LV), and guided mpc injections through endocardium. RESULTS: We successively established that: (1) adequate preimplantation handling of mpc can be achieved when mpc are kept in 0.1% serum albumin-containing medium until implantation; (2) mpc are neither retained nor destroyed in the catheter or the needle and their passage does not affect their survival, growth and differentiation; (3) large numbers of autologous mpc can be actually transplanted in the LV myocardium by transendocardial route, as assessed by post-mortem examination of pigs injected with iron-loaded mpc; (4) cell injection into the myocardium does not induce conspicuous cell mortality since more than 80% of mpc recovered from LV tissue are alive 15 min after injection; (5) mpc injections can be guided into circumscribed LV targets such as infarcted areas, as assessed by comparison of map injection sites with location of iron-loaded mpc at post-mortem examination of LV myocardium. CONCLUSION: This new approach may pave the way for a large spectrum of cell therapies targeting myocardial diseases.
Animals↗
Dilatation of the intrahepatic bile ducts associated with benign liver lesions: an unusual finding.
In three patients presenting different types of liver lesions, including isolated cyst, focal nodular hyperplasia (FNH), and hemangioma, intrahepatic bile duct dilatation was observed on US and CT. Final diagnosis was obtained by surgery in two cases (cyst and FNH) and by 1-year follow-up in one patient presenting an isolated hemangioma. The only common characteristic in our three cases was that lesions were present in segment four according to Couinaud's classification, at the level of the transverse fissure, suggesting that a space-occupying lesion at this site may cause compression of the common hepatic duct and right or left intrahepatic bile ducts. Our report indicates that compression may occur even with lesion of moderate size (35-40 mm in diameter). A benign liver lesion may cause a bile duct dilatation, particularly if located in segment 4, close to the hilum. Awareness of this possibility is important to avoid unnecessary invasive diagnostic procedures, particularly when all imaging criteria are consistent with a benign lesion.
Adult↗
[Imaging in congenital fibrocystic diseases of the liver].
The identification of dilatations of the intrahepatic bile ducts in the absence of bile duct obstruction is rare. Imaging techniques, especially MR cholangio-pancreaticography, generally permit the distinction between fibrocystic liver diseases and polycystic liver diseases. The presence of dilated sacciform or tubular bile ducts on cholangio-pancreaticography associated with a centrally located fibrovascular bundle (central dot sign) suggests Caroli's syndrome. The presence of associated signs of liver dysmorphia including right lobe atrophy and hypertrophy of segment IV suggests associated congenital hepatic fibrosis. The findings on cholangio-pancreaticography, computerized tomography or Doppler ultrasonography correlate well with the pathogenesis of fibrocystic liver diseases, linked to an embryologic malformation of the ductal plate.
Biliary Tract↗