Alain Rahmouni

Liver Cirrhosis: Intravoxel Incoherent Motion MR Imaging—Pilot Study

PURPOSE To retrospectively evaluate a respiratory-triggered diffusion-weighted (DW) magnetic resonance (MR) imaging sequence combined with parallel acquisition to allow the calculation of pure molecular-based (D) and perfusion-related (D*, f) diffusion parameters, on the basis of the intravoxel incoherent motion (IVIM) theory, to determine if these parameters differ between patients with cirrhosis and patients without liver fibrosis. MATERIALS AND METHODS The institutional review board approved this retrospective study; informed consent was waived. IVIM DW imaging was tested on three alkane phantoms, on which the signal-intensity decay curves according to b factors were logarithmically plotted. Ten b factors (0, 10, 20, 30, 50, 80, 100, 200, 400, 800 sec/mm(2)) were used in patients. Patients with documented liver cirrhosis (cirrhotic liver group, n = 12) and patients without chronic liver disease (healthy liver group, n = 25) were included. The mean liver D, D*, and f values were measured and compared with the apparent diffusion coefficient (ADC) computed by using four b values (0, 200, 400, 800 sec/mm(2)). Liver ADC and D, f, and D* parameters were compared between the cirrhotic liver group and healthy liver group. Means were compared by using the Student t test. RESULTS Signal-intensity decay curves were monoexponential on phantoms and biexponential in patients. In vivo, mean ADC values were significantly higher than D in the healthy liver group (ADC = 1.39 x 10(-3) mm(2)/sec +/- 0.2 [standard deviation] vs D = 1.10 x 10(-3) mm(2)/sec +/- 0.7) and in the cirrhotic liver group (ADC = 1.23 x 10(-3) mm(2)/sec +/- 0.4 vs D = 1.19 x 10(-3) mm(2)/sec +/- 0.5) (P = .03). ADC and D* were significantly reduced in the cirrhotic liver group compared with those in the healthy liver group (respective P values of .03 and .008). CONCLUSION Restricted diffusion observed in patients with cirrhosis may be related to D* variations, which reflect decreased perfusion, as well as alterations in pure molecular water diffusion in cirrhotic livers.

Early 18F-FDG PET for Prediction of Prognosis in Patients with Diffuse Large B-Cell Lymphoma: SUV-Based Assessment Versus Visual Analysis

The purpose of this study was to assess the prognostic value of early 18F-FDG PET using standardized uptake value (SUV) compared with visual analysis in patients with diffuse large B-cell lymphoma (DLBCL). Methods: Ninety-two patients with newly diagnosed DLBCL underwent 18F-FDG PET prospectively before and after 2 cycles of chemotherapy (at midtherapy). Maximum SUV (SUVmax) and mean SUV (SUVmean) normalized to body weight and body surface area, as well as tumor-to-normal ratios, were computed on the most intense uptake areas. The SUVs, tumor-to-normal ratios, and their changes over time were compared with visual analysis for predicting event-free survival (EFS) and overall survival, using receiver-operating-characteristic (ROC) analysis. Survival curves were estimated with Kaplan–Meier analysis and compared using the log-rank test. Results: With visual analysis, the accuracy of early PET to predict EFS was 65.2%. The 2-y estimate for EFS was 51% (95% confidence interval [CI], 34%–68%) in the PET-positive group compared with 79% (95% CI, 68%–90%) in the PET-negative group (P = 0.009). An optimal cutoff value of 65.7% SUVmax reduction from baseline to midtherapy obtained from ROC analysis yielded an accuracy of 76.1% to predict EFS. The 2-y estimate for EFS was 21% (95% CI, 0%–42%) in patients with SUVmax reduction ≤ 65.7% compared with 79% (95% CI, 69%–88%) in those with reduction > 65.7% (P < 0.0001). Fourteen patients considered as positive on visual analysis could have been reclassified as good responders. Conclusion: SUV-based assessment of therapeutic response during first-line chemotherapy improves the prognostic value of early 18F-FDG PET compared with visual analysis in DLBCL.

Prognostic Value of Interim 18F-FDG PET in Patients with Diffuse Large B-Cell Lymphoma: SUV-Based Assessment at 4 Cycles of Chemotherapy

Interim 18F-FDG PET (after 1–4 cycles of chemotherapy) may be useful for tailoring a risk-adapted therapeutic strategy in lymphoma. The purpose of this study was to investigate whether semiquantification of standardized uptake values (SUVs) may help to improve the prognostic value of 18F-FDG PET, compared with visual analysis, after 4 cycles of chemotherapy. Methods: In a previous report, we showed that a 65.7% reduction in maximal SUV (SUVmax) between baseline (PET0) and 2 cycles of chemotherapy (PET2) better predicted event-free survival in 92 prospective patients with diffuse large B-cell lymphoma, by reducing false-positive interpretation of visual analysis. Eighty patients also underwent 18F-FDG PET after induction had been completed, at 4 cycles of chemotherapy (PET4). Images were interpreted visually (as negative or positive) and by computing the optimal percentage of SUVmax reduction between PET0 and PET4. Survival curves were estimated using Kaplan–Meier analysis and compared using the log-rank test. Median follow-up was 41 mo. Results: With visual analysis, the 2-y estimate for event-free survival was 82% in the PET4-negative group, compared with 25% in the PET4-positive group (P < 0.0001, accuracy of predicting event-free survival, 81.3%). An optimal cutoff of 72.9% SUVmax reduction from PET0 to PET4 yielded a 2-y estimate for event-free survival of 79% in patients with reduction of more than 72.9%, versus 32% in those with reduction of 72.9% or less (P < 0.0001; accuracy of predicting event-free survival, 77.5%). Conclusion: Although SUV semiquantification helps reduce false-positive interim 18F-FDG PET interpretations at 2 cycles, its performance is equivalent to visual analysis at 4 cycles, when most of the therapeutic effect has occurred upstream. This approach may be useful for objectively tailoring consolidation strategies.

Oral contraceptive use and focal nodular hyperplasia of the liver

BACKGROUND & AIMS Because most patients with focal nodular hyperplasia (FNH) are young women, an important decision is whether to discontinue oral contraceptive (OC) use. The aims of this study were to evaluate (1) the number and size of FNH lesions in women with various patterns of OC use and in women without OC use and (2) the modifications in the number and size of FNH lesions during follow-up, according to OC use. METHODS In a 9-year study in 216 women with FNH, the diameter and number of lesions documented by magnetic resonance (MR) imaging were evaluated (1) at diagnosis according to OC use as follows: group A, no OC use (n = 28); group B, high-dose OC use (n = 46); group C, low-dose OC use (n = 98); group D, successive use of high-dose and low-dose OCs (n = 33); and group E, use of progestogens only (n = 11); and (2) during follow-up in 136 women, 14 of whom were OC nonusers who stayed off OCs, 89 discontinued OC use, 26 took low-dose OCs, and 7 stayed on a progestogen only. Twelve women became pregnant. In 168 women, the diagnosis of FNH was made based on a combination of rigorously defined MR criteria. In the remaining 48 patients, diagnosis was by surgical biopsy (n = 36) or resection (n = 12). Mean diameter and number of lesion(s) per patient were assessed by MR imaging using the same protocol in all study patients. RESULTS No significant differences in the number or size of lesions were found in the 5 patient groups. During follow-up, a change in lesion diameter occurred in only 4 women; this event was not influenced by OC use. In the 12 patients who became pregnant, lesion size was unchanged after delivery, pregnancy was uneventful, and delivery occurred spontaneously. CONCLUSIONS These data suggest that (1) neither the size nor the number of FNH lesions are influenced by OC use; (2) size changes during follow-up are rare and do not seem to depend on OC use; and (3) pregnancy is not associated with FNH changes or complications.

Interim [18F]Fluorodeoxyglucose Positron Emission Tomography Scan in Diffuse Large B-Cell Lymphoma Treated With Anthracycline-Based Chemotherapy Plus Rituximab

PURPOSE The prognostic value of [(18)F]fluorodeoxyglucose-positron emission tomography (PET), interpreted according to visual criteria, is a matter of debate for diffuse large B-cell lymphoma (DLBCL). Moreover, most published studies do not differentiate between patients treated with or without rituximab. We retrospectively investigated the prognostic value of PET performed in patients with DLBCL receiving chemotherapy plus rituximab. Images were interpreted both visually and by computing maximum standardized uptake value (SUV(max)) between PET performed at baseline and after two cycles of chemotherapy. PATIENTS AND METHODS One hundred twelve patients newly diagnosed with DLBCL were treated with an anthracycline-based regimen plus rituximab. A PET was performed after two cycles of treatment. PET positivity or negativity was related to progression-free survival (PFS) and overall survival (OS) using Kaplan-Meier analysis. RESULTS Visual analysis showed that 70 patients (62.5%) presented with a negative PET scan after two cycles of treatment. The 3-year PFS and OS rates were 84% and 88%, respectively, in patients with PET-negative results versus 47% and 62%, respectively, in patients with PET-positive results (P < .0001 and P < .003, respectively). A second analysis was performed on 85 patients by using interim PET in a quantitative approach on the basis of a ΔSUV(max) evaluation of more than 66%. The 3-year PFS was 77% for patients with PET-negative results and 37.5% for patients with PET-positive results (P = .002). CONCLUSION An early PET scan after two cycles of treatment can effectively predict the outcome in patients with DLBCL treated with rituximab and anthracycline-based chemotherapy by using either a visual or quantitative approach.

Accuracy of in-vivo assessment of prostatic volume by MRI and transrectal ultrasonography

More accurate noninvasive estimation of prostate size is important in therapeutic trials for benign prostatic hyperplasia. The accuracy of MRI and transrectal ultrasound (TRUS) in assessing prostate weight was evaluated in 48 patients who underwent radical prostatectomy for stage A or B cancer. The volume derived from the wet weight of the freshly excised specimen was used as a reference. We compared that volume with volume estimates derived from the three-axis linear dimension measurement by MRI and TRUS using a tissue density of 1.05 g/cc and the standard formula for an ellipsoid object. Prostate and seminal vesicle volumes were also computed by contouring T2-weighted 5 mm thick contiguous MR images using a semiautomatic edge detection program and pixel summation. Three-axis volume MRI method versus volume from wet weight has slightly less scatter than TRUS three-axis method (r = 0.85 vs r = 0.81). Contoured MR volume method has the least scatter r = 0.93, statistically better than the linear axis method. Contoured MRI volumetric analysis appears superior to linear MRI or TRUS methods in estimating true prostate volume.

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.

Pulmonary Artery Thrombosis during Acute Chest Syndrome in Sickle Cell Disease

RATIONALE The pathophysiology of acute chest syndrome (ACS) in patients with sickle cell disease is complex, and pulmonary artery thrombosis (PT) may contribute to this complication. OBJECTIVES To evaluate the prevalence of PT during ACS using multidetector computed tomography (MDCT). METHODS We screened 125 consecutive patients during 144 ACS episodes. One hundred twenty-one MDCTs (in 103 consecutive patients) were included in the study. MEASUREMENTS AND MAIN RESULTS Twenty MDCTs were positive for PT, determining a prevalence of 17% (95% confidence interval, 10-23%). Revised Geneva clinical probability score was similar between patients with PT and those without. D-dimer testing was very often positive (95%) during ACS. A precipitating factor for ACS was less frequently found in patients with PT as compared with those without. Patients with PT exhibited significantly higher platelet counts (517 [273-729] vs. 307 [228-412] 10(9)/L, P < 0.01) and lower bilirubin (28 [19-43] vs. 44 [31-71] μmol/L, P < 0.01) levels at the onset of ACS as compared with others. In addition, patients with PT had a higher platelet count peak (537 [345-785] vs. 417 [330-555] 10(9)/L, P = 0.048) and smaller bilirubin peak (36 [18-51] vs. 46 [32-83] μmol/L, P = 0.048)and lactate dehydrogenase peak (357 [320-704] vs. 604 [442-788] IU/L, P = 0.01) during hospital stay as compared with others. CONCLUSIONS PT is not a rare event in the context of ACS and seems more likely in patients with higher platelet counts and lower hemolytic rate during ACS. Patients with sickle cell disease presenting with respiratory symptoms suggestive of ACS may benefit from evaluation for PT.

Response assessment after an inductive CHOP or CHOP-like regimen with or without rituximab in 103 patients with diffuse large B-cell lymphoma: integrating 18fluorodeoxyglucose positron emission tomography to the International Workshop Criteria

BACKGROUND Revised response criteria for aggressive lymphomas have been proposed (Cheson, J Clin Oncol, 2007) stressing the role of (18)fluorodeoxyglucose-positron emission tomography (PET) in posttreatment evaluation. The value of PET after four cycles compared with the International Workshop Criteria (IWC) remains to be established. PATIENTS AND METHODS In all, 103 patients with untreated diffuse large B-cell lymphoma were prospectively enrolled to evaluate the prognostic impact of PET after two and four cycles. RESULTS Median age was 53 years (19-79), 68% male. The International Prognostic Index was low=22%, low-intermediate=19%, intermediate-high=33% and high risk=26%. Treatment consisted of cyclophosphamide, doxorubicin, vincristine, prednisone (CHOP) (30%) or dose-intensified CHOP (70%), with rituximab (49%) or without (51%). Ninety-nine patients were evaluated by PET and IWC at four cycles: 77 (78%) had a negative PET, while 22 (22%) remained positive. The 5-year event-free survival (EFS) was 36% for patients with a positive PET versus 80% with a negative examination, whatever the response [complete response (CR) versus partial response (PR)] according to IWC (P<0.0001). Positive PET patients had a 5-year EFS of 58% if in CR/CR unconfirmed by IWC and 0% if not (P<0.0001). The same observations could be made in patients treated with and without rituximab. CONCLUSION The integration of PET in treatment evaluation offers a powerful tool to predict outcome.

Acute swelling of the limbs: magnetic resonance pictorial review of fascial and muscle signal changes

OBJECTIVE This pictorial review analyzes the magnetic resonance (MR) fascial/muscular changes in 69 patients referred as emergencies with acute swelling of the limbs (ASL) from various causes. METHODS AND MATERIAL A prospective MR imaging (MRI) study of 69 patients referred as emergencies for ASL was performed. Our population consisted of 45 patients with skin and soft-tissue infections (cellulitis and necrotizing fasciitis, and pyomyositis), six patients with soft-tissue inflammatory diseases (dermatomyositis, graft-versus-host disease), 11 patients with acute deep venous thrombosis, three patients with rhabdomyolysis, one patient with acute denervation and three other patients with rare diseases. Hematomas, tumorous or infectious bone involvement and soft-tissue tumors were excluded. All studies included spin echo T1-weighted images and spin echo T2-weighted images. Gadolinium-enhanced spin echo T1-weighted images were obtained when an abscess was suspected on T2-weighted images. Selective fat-saturated T1- and T2-weighted sequences were also used. MRI analysis was performed to obtain a compartmentalized anatomical approach according to the location of signal abnormalities in subcutaneous fat, superficial and deep fascia and muscle. RESULTS In all patients with ASL, MRI demonstrated soft-tissue abnormalities involving subcutaneous fat, superficial fascia, deep fascia, or muscle. Although MR findings were non-specific, MRI appears sensitive for detecting subtle fascial and muscle signal changes. CONCLUSIONS In skin and soft-tissue infections, MRI can be helpful for therapeutic management by determining the depth of soft-tissue involvement, particularly within fasciae and muscles, which is partly related to the severity of cellulitis with severe systemic manifestations. MRI can also aid the surgeon in diagnosing abscesses. In inflammatory diseases, MRI can determine the best site for biopsy and also monitor therapeutic response.