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Biomedical subjects

F Bénard

Publications and source records attributed to F Bénard.

17 recordsLinked to original sources
PubMed2000

Impact of attenuation correction on the accuracy of FDG-PET in patients with abdominal tumors: a free-response ROC analysis.

The aim of this study was to evaluate image quality and lesion detectability with and without attenuation correction in patients with abdominal tumors, using a free-response receiver operating characteristic (FROC) methodology. Thirty-four patients with various abdominal tumors were evaluated (11 men, 23 women, median age 48 years). Whole-body emission scans were performed 68 min (35-102 min) after intravenous injection of 4.3 MBq/kg fluorine-18 fluorodeoxyglucose (FDG). Images were reconstructed using the OS-EM algorithm and corrected for attenuation either using postinjection singles transmission (n=27) or by calculation and body outline (n=7). Total scan duration did not exceed 70 min. Studies were read independently by four observers unaware of any clinical data. The uncorrected (UC) images were systematically read before the attenuation-corrected (AC) images. All studies were given an image quality score ranging from 1 (unreadable) to 5 (excellent). Each focus of increased activity was then localized and given a probability of malignancy using a five-point scale. The average image quality score was similar for both UC and AC images. At the time of the positron emission tomography (PET) scans, 127 lesions (63 liver metastases, 9 retroperitoneal lesions, 50 peritoneal or bowel lesions, and 5 pancreatic carcinomas) were revealed by pathological or correlative studies. The areas under the FROC curves were consistently greater for AC images (range 0.8663-0.8867) than for UC images (range 0.7774 -0.8613). Overall, the difference between the AC images and the UC images was significant (P=0.019). In particular, correction for attenuation increased the sensitivity regardless of the location of the lesions. In conclusion, correction for attenuation significantly improves the diagnostic accuracy of FDG-PET for abdominal staging of neoplasms, without impairing the image quality.

Abdominal Neoplasms↗
PubMed2000

Fluorine-18 fluorodeoxyglucose positron emission tomography correlated with computed tomographic scan and magnetic resonance imaging in a case of hematometrocolpos.

A 12-year-old girl had intense abdominal pain that had increased in the past 3 months and was accompanied by weight loss. An ultrasound examination revealed large cystic masses in the abdomen. A computed tomographic scan could not conclusively rule out a malignant condition. The hymen was normal on physical examination, but magnetic resonance imaging confirmed that the abnormalities corresponded to dilated cavities of the vagina, uterus, and fallopian tubes, with an appearance suggestive of hematometrocolpos. Fluorine-18 fluorodeoxyglucose (FDG) positron emission tomography was requested concurrently with the magnetic resonance image to assess the metabolic activity of the lesions and to exclude the presence of distant metastases. Large defects without FDG accumulation were noted in the areas corresponding to the cystic masses. Vaginal atresia with hematometrocolpos was confirmed at surgery. This rare case involving F-18 FDG positron emission tomographic imaging in hematometrocolpos illustrates that this diagnosis should be considered in the presence of symmetric hypometabolic masses in the pelvis.

Child↗
PubMed2000

Regional cerebral glucose metabolism in healthy volunteers determined by fluordeoxyglucose positron emission tomography: appearance and variance in the transaxial, coronal, and sagittal planes.

PURPOSE: In this study, the contribution of the transaxial, coronal, and sagittal planes in evaluations of regional cerebral glucose metabolism was investigated in healthy volunteers as determined by fluorine-18-labeled 2-deoxy-2-fluoro-D-glucose (FDG) and high-resolution positron emission tomography (PET). METHODS: One hundred twenty-seven healthy right-handed volunteers were injected with 4.2 MBq/kg (0.11 mCi) body weight FDG and imaged in a PENN PET H 240 scanner. Images were corrected for scatter and random coincidences and reconstructed in all three planes into 6- to 8-mm-thick slices. The reconstructed images were corrected for attenuation using the Chang algorithm. The transverse, coronal, and sagittal images were read independently of each other using a qualitative scale in which 1 = equal to, 2 = mildly, 3 = moderately, and 4 = markedly less than the area with the highest glucose metabolism in the respective plane. RESULTS: The areas with the highest glucose metabolisms were the posterior cingulate gyri with mean scores of 1.1 to 1.2, thalami (1.2 to 1.3), basal ganglia (1.5 to 1.9), and visual cortex (1.6). The lowest values were found in the occipital cortex (2.7 to 2.8) and the cerebellum (2.3 to 2.4). Whereas reliable analysis of the mesial temporal aspects was not feasible in the sagittal plane, the anterior poles of the temporal and frontal lobes could not be evaluated in the coronal or the inferior temporal areas in the transaxial slices. In all three planes, regional glucose metabolism was less in the lateral temporal areas on the left than on the right (P < 0.001). The consistency of readings as measured in terms of coefficients of variation was greatest in the coronal plane for the caudates and posterior cingulate gyri, in the transaxial plane for the lateral temporal regions, and in the sagittal plane for the visual cortex. Age-dependent decreases in regional glucose metabolism in the inferior and lateral frontal regions and the parietal lobes were found in all three planes. CONCLUSIONS: All three projection planes must be used for a comprehensive qualitative evaluation of the regional glucose metabolism of the brain.

Adult↗
PubMed2000

Long term follow-up of intravesical Bacillus Calmette-Guerin for the treatment of bladder transitional cell carcinoma.

OBJECTIVE: To review the long-term follow-up, in terms of recurrence and progression, of transitional cell carcinoma of the bladder treated with intravesical BCG with the following indications: CIS, Ta and T1. MATERIALS AND METHODS: Ninety-two patients who had received complete course of BCG between 1987 and 1993 were included in the study and followed for an average of 59 months (range 12 to 102). RESULTS: The recurrence and progression were looked at. Patients treated with BCG for Carcinoma in situ, 11 of 19 (53%) remained tumor-free after 1 or 2 courses of BCG for the duration of the follow-up (mean 4.9 years, range 1.5 to 8.5 years). For patients treated for recurring tumors, 17 of 50 (34%) had no recurrences after 1 or 2 courses of BCG with the same follow-up. When facing multiple tumors, 10 of 23 (43%) patients did not experience recurrences. Therefore, in the 92 patients treated, 38 presented no recurrences after 1 or 2 courses of BCG, for a success rate of 41%. In terms of progression, of the 19 patients treated with BCG for CIS, 4 (21%) went on to develop muscle invasive disease. Of the 50 patients treated for recurrent tumors, 2 (4%) eventually developed lamina propria invasion (initial lesion was a Ta tumor), 4 (8%) carcinoma in situ and 7 (14%) muscle invasive disease, for an overall progression rate of 26% in this group. Of the 25 patients treated for multiple tumors, 1 (4%) developed CIS and 3 (12%) presented with muscle invasive disease, for an overall progression rate of 16% for the duration of the follow-up. Therefore, 21 of 92 (23%) patients had progression of their disease following BCG therapy. No prognostic factors for recurrence or progression could be identified in these tumors. CONCLUSION: When indications warrant its use, BCG is effective in reducing recurrences and limiting progression in TCC of the bladder. Recurrence within 2 years of treatment is, however, a sign of poor prognosis and other therapeutic options should be sought.

Adjuvants, Immunologic↗
PubMed1999

Effectiveness of in vitro fertilization with intracytoplasmic sperm injection for severe male infertility.

BACKGROUND: In its 1993 report the Canadian Royal Commission on New Reproductive Technologies challenged the effectiveness of in vitro fertilization for severe male infertility. To address the Commission's concern, the authors compared the relative effectiveness of in vitro fertilization combined with intracytoplasmic sperm injection for severe male infertility and conventional in vitro fertilization for complete tubal occlusion in women. METHODS: This historical cohort study was done at the PROCREA Fertility Centre, a private tertiary human reproduction centre in Montreal. Three groups of infertile couples were compared: 122 couples with severe male infertility treated by in vitro fertilization with intracytoplasmic injection of fresh sperm from ejaculate (group 1); 27 couples with obstructive azoospermia treated by in vitro fertilization with intracytoplasmic injection of epididymal sperm (collected by microepididymal or percutaneous epididymal sperm aspiration) (group 2); and 98 couples with tubal factor infertility (bilateral tubal occlusion) treated with conventional in vitro fertilization (with sperm from ejaculate) (group 3). The main outcomes measured were rates of fertilization, pregnancy, clinical pregnancy and implantation. RESULTS: Pregnancy rates per started cycle were 35%, 40% and 34% for groups 1, 2 and 3 respectively. When prognostic factors were controlled for, none of the outcome measures differed significantly between the 3 groups. INTERPRETATION: In vitro fertilization with intracytoplasmic injection of sperm from the ejaculate or the epididymis is as effective for treating severe male infertility as conventional in vitro fertilization is for treating complete occlusion of the fallopian tubes in women.

Adult↗
PubMed1999

Long-term followup of initial Ta grade 1 transitional cell carcinoma of the bladder.

PURPOSE: We evaluate the long-term outcome of initial Ta grade 1 transitional cell carcinoma. MATERIALS AND METHODS: A total of 152 patients with initial Ta grade 1 bladder tumor were followed for a mean of 76 months (range 6 to 241). Recurrence was defined as positive findings on cystoscopy or biopsy. Progression was defined as an increase in tumor grade or stage. RESULTS: Tumor recurrence in 83 of 152 patients (55%) was noted within 12 months of followup in 38 patients (46%), between 12 and 24 in 11 (13%), and between 24 and 60 in 22 (27%). A significant number of recurrences (12, 14%) were diagnosed more than 60 months after the first tumor. Of 83 patients with recurrence 31 (37%) had progression, including 21 to grade 2 and 2 to grade 3 disease. Carcinoma in situ was diagnosed in 3 patients and 5 had muscle invasive disease. Progression occurred more than 24 months after initial diagnosis in 20 patients and more than 60 months after first tumor event (2 had carcinoma in situ and 2 had muscle invasive disease) in 12. CONCLUSIONS: Ta grade 1 bladder transitional cell carcinomas have a high recurrence rate and progression is not uncommon. These findings warrant close long-term followup, even when in some settings the trend is to discontinue followup after 5 years without any abnormal findings.

Adult↗
PubMed1999

Prognostic value of FDG PET imaging in malignant pleural mesothelioma.

UNLABELLED: Despite several attempts at treating malignant pleural mesothelioma with various modalities, mortality remains high, with median survival between 12 and 18 mo. This disease may have a highly variable clinical course, with occasional long-term survivors. The purpose of this study was to assess whether tumor metabolic activity, as assessed by fluorodeoxyglucose (FDG) PET imaging, correlates inversely with survival. METHODS: Twenty-eight patients with suspected mesothelioma underwent FDG PET scanning between September 1995 and May 1997. A diagnosis of mesothelioma was confirmed in 22. Fully corrected scans with attenuation correction of the entire chest were available in 17 patients with sufficient follow-up for survival analysis. Standardized uptake values (SUVs) were determined from the most active tumor site in each patient. RESULTS: Seven patients died during follow-up, at a median period of 5.3 mo after FDG PET scanning. Follow-up information was available on the remaining 10 patients for a median period of 15.6 mo after the PET study. The mean SUV of the deceased patients was 6.6+/-2.9, compared with 3.2+/-1.6 among the combined survivors. The deceased patients had tumor SUVs that were highly correlated with duration of survival after the PET study (r = 0.87, P < 0.05). The cumulative survival estimate by the Kaplan-Meier product limit method was 0.17 at 12 mo for the patients with tumor SUVs greater than the median value and 0.86 for those with lower SUVs. The survival distribution of the high SUV group showed significantly shorter survivals compared with the low SUV group (P < 0.01). CONCLUSION: Patients with highly active mesotheliomas on FDG PET imaging have a poor prognosis. High FDG uptake in these tumors indicates shorter patient survival.

Aged↗
PubMed1999

Clinical evaluation of processing techniques for attenuation correction with 137Cs in whole-body PET imaging.

UNLABELLED: Transmission scanning can be successfully performed with a 137Cs single-photon emitting point source for three-dimensional PET imaging. However, the attenuation coefficients provided by this method are underestimated because of the energy difference between 662- and 511-keV photons, as well as scatter and emission contamination when the transmission data are acquired after injection. The purpose of this study was to evaluate, from a clinical perspective, the relative benefits of various processing schemes to resolve these issues. METHODS: Thirty-eight whole-body PET studies acquired with postinjection singles transmission scans were analyzed. The transmission images were processed and applied to the emission data for attenuation correction. Three processing techniques were compared: simple segmentation (SEG) of the transmission scan, emission contamination subtraction with scaling (ECS) of the resulting data to 511-keV attenuation coefficient values and a hybrid technique performing partial segmentation of some tissue densities on the ECS scan (THR). The corrected emission scans were blindly assessed for image noise, the presence of edge artifacts at the lung-soft-tissue interface and for overall diagnostic confidence using a semiquantitative scoring system. The count densities and the SDs in uniform structures were compared among the various techniques. The observations for each method were compared using a paired t test. RESULTS: The SEG technique produced images that were visually less noisy than the ECS method (P < 0.0001) and the THR technique, but at the expense of increased edge artifacts at the boundaries between the lungs and surrounding tissues. The THR technique failed to eliminate these artifacts compared with the ECS technique (P < 0.0001) but preserved the activity gradients in the hilar areas. The count densities (and thus, the standardized uptake values) were similar among the three techniques, but the SEG method tended to underestimate the activity in the lung fields and in chest tumors (slope = 0.79 and 0.94, respectively). CONCLUSION: For many clinical applications, SEG data remain an efficient method for processing 137Cs transmission scans. The ECS method produced noisier images than the other two techniques but did not introduce artifacts at the lung boundaries. The THR technique, more versatile in complex anatomic areas, allowed good preservation of density gradients in the lungs.

Cesium Radioisotopes↗
PubMed1998

Detection of unsuspected recurrent lymphoma with fluorodeoxyglucose-positron emission tomographic imaging after induction chemotherapy: a case study.

We performed a fluorodeoxyglucose-positron emission tomographic (FDG-PET) study on a patient who had high-grade lymphoma thought to be in complete remission. The patient underwent the PET study before being considered for high-dose consolidation therapy because he was thought to be at high risk for relapse. The whole-body FDG-PET study revealed an unsuspected hypermetabolic mass in the lower spine that was not visualized on computed tomographic (CT) scanning. The other laboratory values were normal, with the exception of mild lactate dehydrogenase elevation. Two weeks later, the patient developed low back pain, and magnetic resonance imaging showed a 2-cm paraspinal mass at the level of L4. Bone-marrow biopsy confirmed recurrent lymphoma. Remission was not achieved after another chemotherapy regimen. Fluorodeoxyglucose-positron emission tomography can be helpful in the restaging of lymphoma patients after induction chemotherapy and may help to detect early recurrence in selected situations.

Adult↗
PubMed1998

Metabolic imaging of malignant pleural mesothelioma with fluorodeoxyglucose positron emission tomography.

BACKGROUND: The diagnosis of malignant mesothelioma is a challenging medical problem. CT often cannot differentiate between benign diffuse pleural thickening and malignant mesothelioma, while thoracentesis and CT-guided biopsies are insensitive. We have assessed the value of positron emission tomography (PET) with 2-fluoro-2-deoxy-D-glucose (FDG) in the evaluation of malignant mesothelioma. METHODS: Twenty-eight consecutive patients referred for the evaluation of suspected malignant mesothelioma were evaluated by FDG-PET imaging. Measured attenuation correction was performed in 26 of 28 cases for quantitation with the standardized uptake value (SUV) method. The results of PET imaging were compared with those of video-assisted thoracoscopy or surgical biopsies. RESULTS: Surgical biopsy specimens confirmed the presence of malignant disease in 24 patients and demonstrated benign processes in the remaining four. The uptake of FDG was significantly higher in malignant than in benign lesions (SUV=4.9+/-2.9 and SUV=1.4+/-0.6, respectively; p<0.0001). With a SUV cutoff of 2.0 to differentiate between malignant and benign disease, a sensitivity of 91% and a specificity of 100% could be achieved, although the activity in some epithelial mesotheliomas tended to be close to this threshold. FDG-PET images provided excellent delineation of the active tumor sites. Hypermetabolic lymph node involvement was noted on FDG-PET images in 12 patients, 9 of which appeared normal on CT scans. Histologic examination in six patients confirmed malignant nodal disease in five cases and indicated granulomatous lymphadenitis in one. CONCLUSION: In this highly selected population, FDG-PET imaging was a sensitive method to identify malignant mesothelioma and determine the extent of the disease process.

Biopsy↗
PubMed1998

PET evaluation of therapeutic limb perfusion in Merkel's cell carcinoma.

An 87-yr-old woman diagnosed with recurrent Merkel's cell carcinoma was treated with therapeutic limb perfusion and underwent PET scanning with 18F-fluorodeoxyglucose (FDG). PET studies were obtained before and after treatment to determine the response to the intervention. A baseline whole-body study was obtained to assess the extent and degree of disease activity. This was followed by a repeat PET scan 2 mo. later after treatment with isolated limb chemotherapy with high-dose melphalan and tumor necrosis factor-alpha. The initial scan demonstrated multiple foci of high FDG uptake in the left calf, a left supraclavicular lesion and also detected concurrent keratinizing squamous cell metastasis in the right axilla. A repeat PET study showed complete metabolic resolution of the lesions in the left calf after treatment. FDG PET may be a useful technique for staging Merkel cell carcinoma and for assessing the tumor response after therapy of this rare tumor.

Aged↗
PubMed1996

False-positive 201thallium study in Wolff-Parkinson-White syndrome.

Wolff-Parkinson-White syndrome (WPW) is known to cause abnormal rest electrocardiogram and stress tests. Consequently, the diagnosis of coronary artery disease (CAD) may be difficult in patients with WPW. Previous reports have described false positive stress 201thallium studies in WPW, but the absence of CAD has rarely been confirmed by coronary angiography. A case of false positive stress 201thallium scintigraphy confirmed by angiography is presented. Left ventricular contractile asynchrony can explain the defects observed in myocardial perfusion scintigraphy. The importance of the defects relates to the length of the delta wave.

Adult↗
PubMed1995

Rapid washout of technetium-99m-MIBI from a large parathyroid adenoma.

We report a case of rapid 99mTc-methoxyisobutylisonitrile (MIBI) clearance from a parathyroid adenoma. A double-phase 99mTc-MIBI parathyroid scintigraphy was performed on a 62-yr-old female evaluated for primary hyperparathyroidism. A large parathyroid adenoma was visualized caudal to the left lobe of the thyroid gland with an unusually rapid washout of the tracer from tumor tissue. Histologic tissue examination confirmed the presence of a parathyroid adenoma and the absence of oxyphil cells. Care should be taken in interpretation of 99mTc-MIBI parathyroid scintigrams because some adenomas can present a rapid release of the radiotracer in a double-phase study. Technetium-99m-MIBI retention could be related to the number of mitochondria-rich cells in parathyroid adenomas or to hyperplasia.

Adenoma↗
PubMed1994

[Para-clinical tests and follow-up of breast cancer: how do Quebec oncologists use them?].

To assess the use of complementary tests by oncologists during staging and follow-up of breast cancer patients, a study was performed comparing actual procedures with current literature recommendations. A survey concerning the use of biochemical, radiological and radionuclide tests was presented to a sample of 58 radiation oncologists and medical oncologists involved in the treatment of breast cancer patients, with a 71% response rate. During the post-treatment surveillance, respectively 3%, 24%, 37%, 76% and 96% of the physicians scheduled liver scans, liver ultrasounds, bone scans, chest roentgenograms or mammograms on a regular basis. The frequency of use of various procedures are reported with a reference to the cost-benefit ratio, a matter of current interest. Although most oncologists limit their use of diagnostic tests, some still rely on extensive work-up to detect early recurrences or metastases, an approach that remains controversial in today's literature.

Aftercare↗
PubMed1990

Self-administration in the pharmacological treatment of impotence.

Recent innovative research into the physiology and pharmacology of erection and the introduction of intracavernous injection of vasoactive agents have revolutionised our approach to the diagnosis and treatment of impotence. A thorough understanding of the rationale, indications, precautions and potential complications of intracavernous self-injection is essential for successful management. The commonly used drugs for injection are papaverine, either alone or in combination with phentolamine, and alprostadil (prostaglandin E1). The major adverse effects include priapism, prolonged erection, and fibrosis of the erectile tissue. With the proper technique and appropriate dosage, this is a safe, minimally invasive, and highly effective treatment.

Animals↗