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Biomedical subjects

P Matheja

Publications and source records attributed to P Matheja.

32 records · Page 2Linked to original sources
PubMed1998

Positron emission tomography with F-18-deoxyglucose in patients with differentiated thyroid carcinoma, elevated thyroglobulin levels, and negative iodine scans.

INTRODUCTION: In patients with differentiated thyroid carcinoma, elevated serum levels of thyroglobulin (hTg) may occur in spite of otherwise negative diagnostic procedures and in particular in spite of a negative iodine-131 scan. Positron emission tomography with F-18-deoxyglucose (FDG-PET) is a potentially useful method for the detection of metastatic lesions or the recurrence of thyroid cancer. We aimed to investigate whether FDG-PET is capable of detecting metastatic lesions or recurrence in patients with differentiated thyroid carcinoma, elevated serum levels of thyroglobulin, and otherwise negative diagnostic procedures, including the iodine-131 scan. METHODS: From a group of 500 patients with differentiated thyroid carcinoma, a subgroup of 32 patients had elevated serum hTg-levels, negative iodine- 131 scans, negative cervical and abdominal ultrasound, and negative X-ray of the chest. In 12 of these patients (hTg 77.8+/-94.3 ng/ml, range 1.5-277 ng/ml, median 20 ng/ml), FDG-PET was performed. All but one FDG-PET study was performed in a state of hypothyroidism (TSH 75.8+/-32.2 microIU/ml, range 31-116 microIU/ml, median 74.6 microIU/ml). RESULTS: In 6 of the 12 patients investigated, the FDG-PET was positive. In three of the patients, the diagnosis was confirmed by computed tomography or magnetic resonance imaging. In patients with a positive FDG-PET finding, the hTg level was 146.7+/-90.1 ng/ml (23-277 ng/ml, median 144.5 ng/ml). In contrast, in patients with a negative finding the hTg level was only 9.0+/-7.6 ng/ml (range 1.5-17 ng/ml, median 8.1 ng/ml), P=0.01. CONCLUSION: These preliminary results show that in patients with differentiated thyroid carcinoma, elevated hTg levels, and otherwise negative "conventional" diagnostic procedures, FDG-PET is helpful in detecting metastatic lesions.

Adenocarcinoma, Follicular↗
PubMed1998

Diagnosis of recurrent glioma with SPECT and iodine-123-alpha-methyl tyrosine.

UNLABELLED: Iodine-123-alpha-methyl tyrosine (IMT) allows the investigation of amino acid transport rate in brain neoplasms. It was the aim of this study to evaluate the potential of IMT-SPECT to diagnose the recurrence of gliomas after primary therapy. METHODS: Using a triple-headed SPECT camera, the cerebral uptake of IMT was determined in 27 patients 22 mo, on average, after surgical removal of a primary brain tumor. Eighteen patients had suffered from high-grade gliomas, and nine had suffered from low-grade tumors. Four patients were examined before and after surgical revision of a presumed tumor recurrence. A total of 31 studies were evaluated. The final diagnosis was based on prospective clinicopathological follow-up. Recurrence was diagnosed in 23 cases, with marked clinical deterioration occurring 3.1 mo, on average, after SPECT, and was confirmed by histopathology in 14 instances. Eight cases were free of recurrence, as evidenced by inconspicuous clinical follow-up, ranging from 6 mo to 17 mo after SPECT in seven cases, and by clinical course and histopathology in the remaining subject. RESULTS: Patients with recurrence had significantly higher ratios of IMT uptake in the tumor area to that in a background region than did patients without recurrence (2.27 +/- 0.59 compared to 1.47 +/- 0.29; p < 0.002). The best cutoff level of the IMT uptake ratio in the differentiation between recurrence and benign posttherapeutic lesion was 1.8. Using this study-specific discrimination threshold, the sensitivity and specificity of IMT-SPECT for detecting glioma recurrence were 18 of 23 (78%) and 8 of 8 (100%), respectively. The area under the binormal receiver operating characteristic curve, fitted to the data, was 0.90 +/- 0.06. CONCLUSION: Iodine-123-alpha-methyl tyrosine-SPECT is a promising new tool in the follow-up of patients with gliomas after primary therapy.

Adult↗
PubMed1998

Measurement of temporal asymmetries of glucose consumption using linear profiles: reproducibility and comparison with visual analysis.

AIM: One approach to regionally analyze temporal glucose consumption consists in drawing linear profiles over the maximal values measured in the temporal cortical ribbon. The aim of our study was to test the reproducibility of this method and to compare its diagnostic performance to that of visual analysis in patients with complex partial seizures (CPS). METHODS: Regional cerebral glucose consumption (rCMRGIc) was measured interictally in 25 CPS patients and 10 controls using F-18-deoxyglucose and the positron emission tomography (PET) camera ECAT EXACT 47. The PET scans were visually analyzed for the occurrence of unilateral temporal hypometabolism. Furthermore, rCMRGIc was quantified on six contiguous coronal planes by manually tracing maximal values of temporal glucose consumption, thus creating line profiles of temporal glucose consumption for each side. Indices of asymmetry (ASY) were then calculated from these line profiles in four temporal regions and compared to the corresponding 95% confidence intervals of the control data. All analyses were performed by two observers independently from each other and without knowledge of the clinical findings. RESULTS: The agreement between the two observers with regard to focus lateralization was 96% (kappa = 0.93) on visual analysis and 100% (kappa = 1) on quantitative analysis. There was an excellent agreement with regard to focus lateralization between visual and quantitative evaluation (kappa = 0.8). CONCLUSION: Quantitation of local temporal rCMRGIc by using linear profile analysis is highly reproducible; for the lateralization of epileptogenic foci, however, this method does not possess significant advantages over the visual evaluation of the scans.

Adult↗
PubMed1998

PET and SPECT in medically non-refractory complex partial seizures. Temporal asymmetries of glucose consumption, benzodiazepine receptor density, and blood flow.

AIM: In contrast to medically refractory complex partial seizures (CPS), only limited knowledge exists on cerebral perfusion and metabolism in medically non-refractory CPS. The aim of this study was to investigate the frequency of temporal asymmetries in regional cerebral glucose consumption (rCMRGlc), regional cerebral blood flow (rCBF), and regional cerebral benzodiazepine receptor density (BRD) in this group of patients. METHODS: The study included 49 patients with medically non-refractory cryptogenic CPS (age: 36.0 +/- 16.1 years). rCMRGlc was studied with F-18-FDG-PET (FDG), rCBF with Tc-99m-ECD-SPECT (ECD), and BRD with l-123-iomazenil-SPECT (IMZ). All studies were performed interictally and within four weeks in each patient. Duration of epilepsy ranged from 0.1 to 42 years (median 4.0 years). SPECT was performed with the triple-headed SPECT camera Multispect 3, PET with the PET camera ECAT EXACT 47. Using linear profiles, glucose consumption, as well as uptake of ECD and IMZ, were measured in four temporal regions of interest (ROIs), and asymmetry indices were calculated (ASY). The results were compared to 95% confidence intervals determined in control subjects. RESULTS: Thirty-five of the 49 (71%) patients had at least one significantly elevated ASY; temporal rCMRGlc was asymmetrical in 41% of the patients, temporal BRD in 29%, and temporal rCBF in 24%. One patient had an asymmetry of all three variables, two of temporal rCMRGlc and BRD, three of temporal rCMRGlc and rCBF, and another four of rCBF and BRD. Fourteen patients had an isolated temporal asymmetry in rCMRGlc, seven in BRD, and four in rCBF. A discrepancy in lateralization between the three modalities was not observed. CONCLUSION: The majority of patients with medically non-refractory CPS have focal abnormalities of blood flow and metabolism in their temporal lobe. In this group of patients, FDG-PET demonstrates abnormalities with the highest frequency of the three modalities studied, followed by IMZ-SPECT, and ECD-SPECT.

Adolescent↗
PubMed1997

Non-invasive grading of primary brain tumours: results of a comparative study between SPET with 123I-alpha-methyl tyrosine and PET with 18F-deoxyglucose.

Use of iodine-123-alpha-methyl tyrosine (123I-IMT) allows investigation of the amino acid transport rate in gliomas. It was the aim of this study to compare the value of measurement of glucose metabolism with that of measurement of 123I-IMT uptake for the non-invasive grading of brain tumours. The study population comprised 23 patients with histopathologically proven primary brain tumours; 14 had high-grade gliomas, and nine low-grade brain neoplasms. Glucose metabolism was studied using an ECAT EXACT 47 positron emission tomography (PET) camera and fluorine-18 fluorodeoxyglucose (18F-FDG); 123I-IMT uptake was measured with the triple-headed single-photon emission tomography (SPET) camera, MULTISPECT 3. 18F-FDG and 123I-IMT uptake was quantified as ratios between the uptake by the tumour and contralateral regions of reference. Glucose metabolism and amino acid uptake of the brain tumours correlated significantly (r=0.71, P <0.001). Assuming discrimination thresholds between high-grade and low-grade tumours of 0.8 for 18F-FDG uptake and 1.8 for 123I-IMT uptake, the accuracy values of 18F-FDG PET and 123I-IMT SPET for differentiating between high-grade and low-grade tumours were 21/23 (91%) and 19/23 (83%), respectively. The difference in diagnostic performance was not significant on receiver operating characteristic analysis (P >0.4). It is concluded that there is no major difference between the PET investigation of glucose metabolism and the less expensive SPET measurement of amino acid uptake in terms of their accuracy in evaluating the malignancy grade of primary brain tumours. This encourages the performance of further studies to analyse the potential impact of 123I-IMT SPET on the therapeutic management of patients with brain tumours.

Adult↗
PubMed1997

Frontal sinus mucocele mimicking a metastasis of papillary thyroid carcinoma.

Radioiodine scans are highly specific for detecting metastases of well-differentiated thyroid carcinomas. However, false-positive 131I whole-body scans may occur as illustrated in the following case report. In a 53-yr-old patient, abnormal 131I uptake was found in the right frontal skull 4 wk after total thyroidectomy and radioiodine therapy for papillary thyroid cancer. Bone scans and planar x-rays of the skull were unremarkable and the serum thyroglobulin level was within normal limits. X-ray CT revealed a small nodule in the right frontal sinus corresponding to the pathological focus of 131I uptake. Surgical removal and histopathological examination of this lesion yielded a mucocele, a slow-growing lesion of the paranasal sinuses accumulating mucous material. The postoperative 131I scan was unremarkable. The possibility of a false-positive finding on radioiodine scans should be considered, particularly when the serum thyroglobulin level is not elevated.

Carcinoma, Papillary↗
PubMed1997

Iodine-123-alpha-methyl tyrosine in gliomas: correlation with cellular density and proliferative activity.

UNLABELLED: Amino acid transport rate in gliomas can be assessed using SPECT and the amino acid L-123I-alpha-methyl tyrosine (IMT). This study attempted to correlate the uptake of IMT by gliomas with the proliferative activity and cellular density of these neoplasms. METHODS: The study used 27 patients with gliomas, including 18 patients with high-grade tumors and nine patients with low-grade neoplasms. Amino acid transport rate was determined using IMT and the triple-headed SPECT camera. Proliferative activity was immunohistochemically assessed as the relative number of cells expressing the Ki-67 nuclear antigen; cellular density was evaluated using light microscopy. RESULTS: Relative IMT uptake correlated significantly with the proliferative fraction of tumor cells (r = 0.6, p < 0.001). There was no significant correlation between IMT uptake and cellular density (r = 0.25, p > 0.05). CONCLUSION: The uptake of the SPECT radiopharmaceutical IMT is related to proliferative activity rather than to the cellular density of gliomas.

Astrocytoma↗
PubMed1996

The clinical impact of thallium-201 reinjection for the detection of myocardial hibernation.

Thallium-201 reinjection improves detection of hibernating myocardium in about 30%-50% of persisting defects. The main goal of cardiac revascularization techniques is amelioration of clinical symptoms such as angina and dyspnoea; however, improvement in regional and global pump function is an additional and important target. The aim of this study was to investigate whether fill-in in the reinjection study is correlated with improved contractile function after treatment (percutaneous transluminal coronary angioplasty/aortocoronary bypass surgery). We studied 32 patients with coronary heart disease and impaired regional wall motion (RWM). RWM and ejection fraction (EF) were assessed by analysing ventriculographic images using the centreline method (values in standard deviations from mean values found in a healthy control group). Three 201Tl single-photon emission tomographic studies (stress, redistribution and reinjection) were performed prior to revascularization and analysed using a bull s-eye scheme. Patients were divided into two groups (group FI-=no fill-in, n=16; group FI+=fill-in, n=16). Fifty-six percent of all patients showed persisting defects, and 56% of these defects showed fill-in after reinjection. Fill-in in our patient group was independent of the size of the persisting defects. After revascularization RWM increased significantly in group FI+ (from -1.9 to 0.0 SD, P<0.001) whereas group FI- showed no significant change (from -1.6 to -1.8 SD). EF increased from -4.3 preoperatively to -2.1 SD postoperatively in group FI+ and did not change significantly in group FI- (-2.5 to -3.2 SD). The predictive value of reinjection for improvement of RWM was 88%. It is concluded that fill-in in the 201Tl reinjection image can predict recovery of RWM and EF after revascularization and should be used in all patients with impaired RWM and persisting defects independent of their extent.

Adult↗
PubMed1996

Uptake of iodine-123-alpha-methyl tyrosine by gliomas and non-neoplastic brain lesions.

Using single-photon emission tomography (SPET), the radiopharmaceutical l-3-iodine-123-alpha-methyl tyrosine (IMT) has been applied to the imaging of amino acid transport into brain tumours. It was the aim of this study to investigate whether IMT SPET is capable of differentiating between high-grade gliomas, low-grade gliomas and non-neoplastic brain lesions. To this end, IMT uptake was determined in 53 patients using the triple-headed SPET camera MULTISPECT 3. Twenty-eight of these subjects suffered from high-grade gliomas (WHO grade III or IV), 12 from low-grade gliomas (WHO grade II), and 13 from non-neoplastic brain lesions, including lesions after effective therapy of a glioma (five cases), infarctions (four cases), inflammatory lesions (three cases) and traumatic haematoma (one case). IMT uptake was significantly higher in high-grade gliomas than in low-grade gliomas and non-neoplastic lesions. IMT uptake by low-grade gliomas was not significantly different from that by non-neoplastic lesions. Diagnostic sensitivity and specificity were 71% and 83% for differentiating high-grade from low-grade gliomas, 82% and 100% for distinguishing high-grade gliomas from non-neoplastic lesions, and 50% and 100% for discriminating low-grade gliomas from non-neoplastic lesions. Analogously to positron emission tomography with radioactively labelled amino acids and fluorine-18 deoxyglucose, IMT SPET may aid in differentiating high-grade gliomas from histologically benign brain tumours and non-neoplastic brain lesions; it is of only limited value in differentiating between non-neoplastic lesions and histologically benign brain tumours.

Adult↗
PubMed1996

[Positron emission tomography. Cost-benefit considerations].

To date, positron emission tomography (PET) is the most powerful tool for the non-invasive study of biochemical processes. Besides its usefulness for basic research PET has been proven to be superior to conventional diagnostic methods in several clinical indications. However, the introduction of PET into clinical practice has been hindered considerably by its costs. Several American studies lend support to the hypothesis that PET may be more cost-effective than the conventional diagnostic work-up-at least for some of its clinical indications. In Germany, however, this hypothesis has still not been verified.

Blood Glucose↗
PubMed1996

Influence of size of regions of interest on the measurement of uptake of 123I-alpha-methyl tyrosine by brain tumours.

The aim of this study was to assess the influence of variations in the size of regions of interest (ROIs) on uptake values in brain tumours of L-3-iodine-123-alpha-methyl tyrosine (IMT). In addition, we attempted to establish the influence of size of ROIs on levels of significance assessing differences in mean IMT uptake between high-grade and low-grade tumours. Relative IMT uptake was determined in 19 patients with brain tumours using a MULTISPECT 3 triple-headed camera. Reconstructed image resolution was 14 mm at FWHM. Ten of the subjects suffered from high-grade gliomas (WHO grade III or IV) and nine from benign brain tumours, including eight patients with low-grade gliomas (WHO grade II). ROIs were defined by selecting those pixels within the tumour that exhibited uptake values above predefined threshold values. Using threshold values of 100, 95, 90, 85 and 80% of the mean, transaxial ROI size was approximately 0.1, 2.8, 4.3, 6.2 and 8.8 cm2, respectively. Over this range, mean, IMT uptake values decreased significantly from 2.4 to 1.9. High-grade tumours exhibited significantly higher IMT uptake than low-grade tumours at each of the threshold values. The corresponding levels of significance calculated using the Mann-Whitney U-test were between 0.01 and 0.02. Although IMT uptake values in brain tumours are significantly dependent on ROI size, levels of significance assessing differences in IMT uptake between high-grade and low-grade tumours are relatively insensitive to variations in this parameter.

Adolescent↗
PubMed1993

201Tl reinjection predicts improvement of left ventricular function following revascularization.

The aim of this study was to evaluate the correlation between improved Tl uptake in reinjection imaging with improvements in regional wall motion and global ejection fraction following PTCA or aorto-coronary bypass surgery. 19 patients with CHD were investigated and divided into two groups according to their thallium uptake in the reinjection studies. Group I showed additional uptake on reinjection imaging compared to the redistribution image, whereas group II showed no additional uptake. Both groups had a similar number and distribution of affected vessels and location of the leading stenosis. Stress, redistribution and reinjection images were obtained prior to revascularization and evaluated semiquantitatively from a bulls eye scheme. There was a postoperative increase in regional wall motion in group 1 from 5.3 to 8.8% whereas group II did not show a relevant change (6.3 vs 6.0%). The ejection fraction increased II from 55.0 to 66.7% in group I and dit not increase in group II (59.8 vs 58.7%). The overall predictive value of the reinjection image for improvement in wall motion (> 10%) was 91% and for the redistribution image 58%. Increased uptake in reinjection imaging predicts improved ventricular function following revascularization and indeed indicates viable myocardium with reversible functional impairment.

Aged↗
PubMed1992

Thallium-201 single photon emission tomography of myocardium: additional information in reinjection studies is dependent on collateral circulation.

A second thallium-201 injection under resting conditions is able to improve the differentiation between myocardial scar and ischaemia when compared with simple redistribution imaging. The aim of this study was to evaluate the dependence of this improvement on the degree of stenosis and the presence of collaterals. Single photon emission tomography (SPET) studies under exercise, redistribution and reinjection conditions were performed on 84 patients with 181 stenotic vessels (70 left anterior descending, 47 left circumflex, 64 right coronary artery) and compared with angiography. An improvement of the 201Tl uptake in the reinjection image was observed in 53% of the myocardial areas served by a coronary artery with a stenosis of over 90%. This is compared with 13% of the areas served by a vessel with a stenosis between 50% and 90%. 90% of the collateralized areas showed a fill-in effect, but only 7 of the 118 without angiographically visible collateralization (6%). The dependence of the fill-in effect, collateralization and stenosis was highly significant (chi 2 test, p less than 0.0001). In our patient group, there was much greater benefit from the reinjection study in vessels with a greater than 90% narrowing. The fill-in effect was closely correlated to the presence of collaterals. In these cases, the fill-in may be an indication for hibernating myocardium.

Collateral Circulation↗