Reiko Usui

Pramipexole for stage 2 treatment-resistant major depression: an open study.

OBJECTIVE To examine the effectiveness and safety of adjunctive pramipexole in the treatment of stage 2 treatment-resistant major depressive disorder. METHODS This study included patients with moderate or non-psychotic severe major depressive disorder according to DSM-IV-TR criteria despite at least two adequate treatment trials with antidepressants from different pharmacological classes. Pramipexole 0.25 to 2 mg daily was added to antidepressant therapy. Previous treatments were continued unchanged, but no new treatments were allowed. We conducted assessments at baseline and at weeks 2, 4, 6, and 8. We defined response as a 50% or greater reduction on the Montgomery-Åsberg Depression Rating Scale (MADRS). RESULTS Ten patients (4 men, 6 women) aged 43.7±11.4 years received pramipexole at mean dose of 1.3±0.6 mg/d. Mean MADRS scores improved significantly from baseline to endpoint (mean differences=11.4, 95% CI [4.1, 18.7], P=0.0064). At the endpoint, six of 10 (60%) were responders on MADRS (≥50% reduction). Two patients (20%) terminated early due to mild somatic and psychiatric adverse effects. CONCLUSION These preliminary data suggest that the addition of pramipexole to antidepressant treatment may be effective and well tolerated in patients with stage 2 treatment-resistant major depressive disorder.

Indolent dorsal midbrain tumor: new findings based on positron emission tomography.

OBJECT Intrinsic tumors arising in the dorsal midbrain cause obstructive hydrocephalus and have an indolent clinical course. Positron emission tomography (PET) with fluorine-18-labeled fluorodeoxyglucose (FDG) and l- [methyl-(11)C]methionine (MET) was used to evaluate the biological behaviors of dorsal midbrain tumors. METHODS The authors report on 4 patients (3 males and 1 female) with dorsal midbrain tumors who presented with obstructive hydrocephalus. A diagnosis was made with MR imaging in each patient. To manage the hydrocephalus, endoscopic third ventriculostomy was performed in all cases. The patients did not undergo any other surgical procedures except endoscopic biopsy procedure, chemotherapy, or radiation therapy. The patients in 3 cases underwent FDG- and MET-PET within 6 months of CSF-diverting procedures, and the patient in 1 case underwent PET 10 years after the procedure. RESULTS After the CSF-diverting procedure, clinical symptoms resolved or improved in all patients. Gliosis or glial proliferation was diagnosed in 1 patient, and possible low-grade glioma in 2 patients. Although all tumors appeared hyperintense on T2-weighted MR images, their appearance on T1-weighted images was variable (iso- and/or hypointense), and partial lesion enhancement was observed on images from 2 patients. On the other hand, the PET features of these lesions were almost identical, and the scans did not show a high uptake of FDG and MET compared with the cortical uptake in a normal brain. The mean tumor tissue/normal tissue ratio of FDG uptake was 0.65, and that of MET was 0.99. CONCLUSIONS Positron emission tomography findings suggested that the indolent dorsal midbrain lesion had nontumorous characteristics, thus supporting a good prognosis. Positron emission tomography studies may be more informative and predictive of the biological behavior of dorsal midbrain tumors than a biopsy procedure.

A pitfall of C-11 methionine PET: cerebral venous infarction mimicked a glioma.

A 31-year-old woman presenting with tonic seizures was radiologically investigated using CT, MR imaging, and positron emission tomography (PET) with F-18 fluorodeoxyglucose (FDG) and C-11 methionine (MET). Initial CT, C-11 MET PET, and F-18 FDG PET suggested a low-grade tumor such as oligodendroglia

11C-Methionine positron emission tomography may monitor the activity of encephalitis

Encephalitis is generally diagnosed by clinical symptoms, cerebrospinal fluid examination, and imaging studies including CT, magnetic resonance imaging (MRI), and perfusion single photon emission tomography (SPECT). However, the role of positron emission tomography (PET) in diagnosis of encephalitis remains unclear. A 49-year-old woman presenting with coma and elevated inflammatory reaction was diagnosed as having encephalitis according to slow activity on electroencephalogram, broad cortical lesion in MR fluid attenuated inversion recovery image, and increased blood flow demonstrated by SPECT. PET revealed increased accumulation of 11C-methionine (MET) in the affected brain tissues. After the symptom had improved 2 months later, the accumulation of MET as well as the abnormal findings of MR imaging and SPECT was normalized. This case indicated that MET PET may monitor the activity of encephalitis.

Regional partition coefficient of water in patients with cerebrovascular disease and its effect on rCBF assessment

ObjectiveCerebral blood flow (CBF) estimation with C15O2 PET usually assumes a single tissue compartment model and a fixed brain–blood partition coefficient of water. However, the partition coefficient may change in pathological conditions. The purpose of this study was to investigate the changes in the partition coefficient of water in pathological regions and its effect on regional CBF assessment. MethodsThe study protocol included 22 patients with occlusive cerebrovascular disease to compare the partition coefficients among three regions (infarction area, noninfarct hypoperfusion area, and contralateral area) in the pathological brain (analysis A), and to compare the CBF estimated by using a fixed partition coefficient and CBF estimated using floating partition coefficients (analysis B). ResultsThe partition coefficient in the infarction area (0.55±0.07 ml/g) was lower than that in the contralateral normal cortex (0.68±0.05 ml/g), whereas noninfarct hypoperfusion area did not show a significant change (0.67±0.06 ml/g). As a result, the use of a fixed partition coefficient of normal volunteers (0.70 ml/g) resulted in an underestimation in regional CBF by 12% in infarction area (P<0.05), whereas the estimation errors were smaller and induced no significant difference in the noninfarct hypoperfusion area or in contralateral areas. ConclusionThe partition coefficient is stable except for the infarction area, and CBF estimation using a fixed partition coefficient of normal volunteers provides clinically appreciable information in patients with cerebrovascular disease.

A New PET Scanner with Semiconductor Detector Reveals Intratumoral Inhomogeneous Cell Activity with High Spatial and Energy Resolution

Objective Intensity-modulated radiation therapy. an advanced mode of high-precision radiotherapy developed to deliver precise radiation doses to specific areas within a tumor, has become popular in the clinical situation. With this modality, it has become particularly important in the clinical situation to estimate accurate cell activity with positron emission tomography (PET) scanner. We developed a new PET scanner with a semiconductor detector. Phantom images and [18F] fluorode-oxyglucose ([18F] FDG)-PET images of patients were measured to evaluate this new scanner’s capacity to identify intratumoral inhomogeneous cell activity.