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Biomedical subjects

U Buell

Publications and source records attributed to U Buell.

At least 37 records · Page 2Linked to original sources
PubMed2000

Diagnosis and staging of head and neck cancer: a comparison of modern imaging modalities (positron emission tomography, computed tomography, color-coded duplex sonography) with panendoscopic and histopathologic findings.

OBJECTIVE: To compare the clinical value of positron emission tomography (PET) using fludeoxyglucose F 18, computed tomography (CT), color-coded duplex sonography (CCDS), and panendoscopy in the detection and staging of head and neck cancer. DESIGN: Prospective nonrandomized controlled study. SETTING: Medical school. PATIENTS: Convenience sample of 50 patients with suspected primary or recurrent head and neck cancer. INTERVENTION: Biopsy, tumor surgery. MAIN OUTCOME MEASURES: Information of diagnostic procedures compared with histopathologic features. RESULTS: Both PET and panendoscopy had a sensitivity of 95% and 100% for detection of primary tumor or recurrent carcinomas, respectively. Specificity for PET and panendoscopy was 92% and 85% in primary tumors and 100% and 80% in recurrent carcinoma, respectively. Sensitivity of CCDS and CT was 74% and 68% in primary tumors and 67% and 63% in recurrent carcinomas, respectively. Specificity was 75% and 69% in primary tumors and 100% and 80% in recurrent neoplasms. When assessing neck nodes, all imaging procedures exhibited identical sensitivity (84%). Specificity was 90%, 96%, and 88% in PET, CT, and CCDS, respectively. In recurrent lymph node metastases, sensitivity was 100%, 67%, and 67% and specificity was 87%, 91%, and 87% for PET, CT, and CCDS, respectively. CONCLUSIONS: Positron emission tomography was the most reliable imaging procedure in the detection of primary tumor and recurrent carcinomas localized in the head and neck region. Owing to its limited anatomical depiction, it cannot as yet replace other diagnostic procedures in preoperative planning but does contribute valuable complementary diagnostic information. Computed tomograpy may have difficulties in identifying recurrent carcinomas. For routine diagnosis of nodal spread in the neck, CCDS is recommended. Panendoscopy is a valuable diagnostic procedure that can provide key information in cases of superficial mucosal tumor involvement. Arch Otolaryngol Head Neck Surg. 2000;126:1457-1461

Biopsy↗
PubMed2000

Diagnosis of myocardial viability by dual-head coincidence gamma camera fluorine-18 fluorodeoxyglucose positron emission tomography with and without non-uniform attenuation correction.

This study assessed a dual-head coincidence gamma camera (hybrid PET) equipped with single-photon transmission for myocardial fluorine-18 fluorodeoxyglucose (FDG) imaging by comparing this technique with conventional positron emission tomography (PET) using a dedicated ring PET scanner. Twenty-one patients were studied with dedicated FDG ring PET and FDG hybrid PET for evaluation of myocardial glucose metabolism, as well as technetium-99m tetrofosmin single-photon emission tomography (SPET) to estimate myocardial perfusion. All patients underwent transmitted attenuation correction using germanium-68 rod sources for ring PET and caesium-137 point sources for hybrid PET. Ring PET and hybrid PET emission scans were started 61+/-12 and 98+/-15 min, respectively, after administration of 154+/-31 MBq FDG. Attenuation-corrected images were reconstructed iteratively for ring PET and hybrid PET (ac-hybrid PET), and non-attenuation-corrected images for hybrid PET (non-ac-hybrid PET) only. Tracer distribution was analysed semiquantitatively using a volumetric vector sampling method dividing the left ventricular wall into 13 segments. FDG distribution in non-ac-hybrid PET and ring PET correlated with r=0.36 (P<0.0001), and in ac-hybrid PET and ring PET with r=0.79 (P<0.0001). Non-ac-hybrid PET significantly overestimated FDG uptake in the apical and supra-apical segments, and underestimated FDG uptake in the remaining segments, with the exception of one lateral segment. Ac-hybrid PET significantly overestimated FDG uptake in the apical segment, and underestimated FDG uptake in only three posteroseptal segments. A three-grade score was used to classify diagnosis of viability by FDG PET in 136 segments with reduced perfusion as assessed by SPET. Compared with ring PET, non-ac-hybrid PET showed concordant diagnoses in 80 segments (59%) and ac-hybrid PET in 101 segments (74%) (P<0.001). Agreement between ring PET and non-ac-hybrid PET was best in the basal lateral wall and in the apical-septal segment (80%-100%), and lowest in the apical, supra-apical and posteroseptal segments (41%-55%). Ac-hybrid PET showed highest agreement in the lateral wall (89%-100%), and lowest agreement in the apical and the basal septal segments (59%-67%). In conclusion, non-uniform attenuation correction with singles transmission significantly improves the diagnostic accuracy of myocardial dual-head gamma camera coincidence imaging with FDG. However, results equivalent to those obtained with ring PET cannot yet be attained, even if attenuation correction is applied. New rebinning algorithms for three-dimensional data may further improve the performance of ac-hybrid PET and should be evaluated in future studies.

Adult↗
PubMed2000

Does thyroid stunning exist? A model with benign thyroid disease.

With regard to the treatment of differentiated non-medullary thyroid carcinoma, there is controversy over whether radiation from a diagnostic radioiodine (131I) application really does have a suppressive effect on the uptake of subsequent therapeutic 131I (so-called thyroid stunning). However, inherent difficulties in exact remnant/metastatic tissue volumetry make it difficult to quantify how much diagnostic 131I is actually absorbed (absorbed energy dose) and hence to decide whether a threshold absorbed dose exists beyond which such stunning would occur. Since in benign thyroid disease the target volume can be readily quantified by ultrasonography, we sought to determine definitely whether stunning of thyroid cells occurs upon a second application of radioiodine 4 days following the first one. We therefore studied 171 consecutive patients with benign thyroid disease (diffuse goitre, Graves' disease, toxic nodular goitre) who received two-step 131I therapy during a single in-patient stay. For application of both calculated 131I activities we performed kinetic dosimetry of 131I uptake, effective half-life and absorbed dose. At the second application, patients showed significant stunning (a 31.7% decrease in 131I uptake, from 34.7% +/- 15.4% at first application to 23.7% +/- 12.3% at second application, P < 0.0005) without a significant difference in effective half-life (4.9 +/- 1.3 vs 5.0 +/- 1.7 days, P > 0.2). ANOVA showed that the extent of stunning was influenced significantly only by the absorbed energy dose at first application (F = 13.5, P < 0.0005), while first-application 131I activity, target volume, gender and thyroid function had no influence (all F < or = 0.71, all P > 0.4). There was no significant correlation between extent of thyroid stunning and first-application 131I activity ( r = 0.07, P > 0.3), whereas there was a highly significant correlation between thyroid stunning and first absorbed energy dose (r = 0.64, P < 0.00005), the latter correlation fitting a logarithmic model best. Multivariate factor analysis also revealed first absorbed energy dose to be the only decisive stunning factor. In conclusion, our study confirms that stunning exists in benign thyroid conditions and that it is a purely radiobiological inhibitory phenomenon related to absorbed dose.

Adult↗
PubMed2000

Benign versus malignant osseous lesions in the lumbar vertebrae: differentiation by means of bone SPET.

Bone scanning is a well-accepted and frequently performed diagnostic procedure with a high sensitivity, especially when single-photon emission tomography (SPET) acquisitions are added. However, the differentiation of benign from malignant osseous lesions often poses difficulty. The purpose of this study was to find out whether the particular localisation of an intraosseous lesion in a lumbar vertebra is an indicator of its aetiology. Bone scintigraphy including planar whole-body scans as well as SPET imaging of the lumbar spine was performed in 109 patients. The diagnoses of osseous lesions in the lumbar vertebrae were made strictly on the basis of the findings of magnetic resonance imaging, computed tomography or plain radiography. Sixteen patients had to be excluded from the study because they did not undergo adequate radiological examination. To determine the particular localisation of vertebral lesions in the bone scan, two experienced nuclear medicine physicians examined the studies independently while blinded to the radiological results. Four anatomical regions were differentiated within the vertebra: the vertebral body, the pedicle, the facet joints and the spinous process. Clopper-Pearson analysis, which takes into account the number of examinations, yielded the following probability intervals for the malignancy of intraosseous lesions in the lumbar spine: vertebral body 36.8%-57.3%, pedicle 87.7%-100%, facet joints 0.8%-21.4% and spinous process 18.7%-81.3%. It was concluded that lesions affecting the pedicle are a strong indicator for malignancy, whereas involvement of the facet joints is usually related to benign disease. Lesions affecting the vertebral body or the spinous process do not show a clear tendency towards either malignancy or benignity. In contrast to other studies, a significant probability of malignancy (35.6%) was observed in lesions affecting exclusively the vertebral body.

Adult↗
PubMed2000

Fluorodeoxyglucose positron emission tomography and the prognosis of pancreatic carcinoma.

BACKGROUND: Pancreatic carcinoma is associated with a poor prognosis. The aim of this study was to determine whether glucose metabolism in pancreatic cancer has prognostic significance for patients suffering from this disease. METHODS: The survival data of 52 patients with pancreatic carcinoma was correlated with the standardized uptake value (SUV) as a semiquantitative parameter of glucose metabolism, as determined with fluorodeoxyglucose positron emission tomography (FDG PET). A multivariate analysis, including SUV and accepted factors of prognosis, such as stage at presentation and tumor marker Ca 19-9, was performed to determine the prognostic value of FDG PET. RESULTS: The median survival in 26 patients with low SUV (< 6.1) was 9 months (95% confidence interval 6-12 months) vs. 5 months (95% confidence interval 4-6 months) in 26 patients with high SUV (> or = 6.1). Multivariate analysis revealed SUV and tumor marker Ca 19-9 as independent factors of prognosis in patients with pancreatic carcinoma. CONCLUSION: Glucose metabolism, as determined with FDG PET, provides additional prognostic information in patients with pancreatic carcinoma.

Adenocarcinoma↗
PubMed2000

Changes in pulmonary blood flow during gaseous and partial liquid ventilation in experimental acute lung injury.

BACKGROUND: It has been proposed that partial liquid ventilation (PLV) causes a compression of the pulmonary vasculature by the dense perfluorocarbons and a subsequent redistribution of pulmonary blood flow from dorsal to better-ventilated middle and ventral lung regions, thereby improving arterial oxygenation in situations of acute lung injury. METHODS: After induction of acute lung injury by repeated lung lavage with saline, 20 pigs were randomly assigned to partial liquid ventilation with two sequential doses of 15 ml/kg perfluorocarbon (PLV group, n = 10) or to continued gaseous ventilation (GV group, n = 10). Single-photon emission computed tomography was used to study regional pulmonary blood flow. Gas exchange, hemodynamics, and pulmonary blood flow were determined in both groups before and after the induction of acute lung injury and at corresponding time points 1 and 2 h after each instillation of perfluorocarbon in the PLV group. RESULTS: During partial liquid ventilation, there were no changes in pulmonary blood flow distribution when compared with values obtained after induction of acute lung injury in the PLV group or to the animals submitted to gaseous ventilation. Arterial oxygenation improved significantly in the PLV group after instillation of the second dose of perfluorocarbon. CONCLUSIONS: In the surfactant washout animal model of acute lung injury, redistribution of pulmonary blood flow does not seem to be a major factor for the observed increase of arterial oxygen tension during partial liquid ventilation.

Animals↗
PubMed2000

Influence of diabetes mellitus on regional cerebral glucose metabolism and regional cerebral blood flow.

Previous studies have shown both increased and decreased regional cerebral glucose metabolism-blood flow (rMRGlu-rCBF) values in diabetes. We sought to elucidate the influence of diabetes on rMRGlu-rCBF in 57 patients with pure cerebral microangiopathy. Sixteen of 57 patients had diabetes requiring therapy (11 NIDDM, 5 IDDM). Using a special head-holder for exact repositioning, rMRGlu (PET) and rCBF (SPET) were imaged and measured in slices, followed by MRI. White matter and cortex were defined within regions of interest taken topographically from MRI (overlay). Diabetic and non-diabetic microangiopathy patients were compared to 19 age-matched controls. The diabetic patients showed significantly lower rMRGlu-rCBF values in all regions than controls, whereas non-diabetic patients did not. There were no significant NIDDM-IDDM differences. rMRGlu-rCBF did not depend on venous blood glucose levels at the time of the PET examination. However, analysis of variance with the factors diabetes, atrophy and morphological severity of microangiopathy showed that lowered rMRGlu-rCBF in the diabetic group was due to concomitant atrophy only (P < 0.005), while neither diabetes nor microangiopathy had any influence on rMRGlu-rCBF (all P > 0.2). These results were confirmed by multivariate factor analysis. It can thus be concluded that a supposed decrease in rMRGlu-rCBF in diabetes mellitus is in fact only an artefact produced by the concomitant atrophy. All previous studies failed to correct for atrophy, and a critical reappraisal is required.

Aged↗
PubMed1999

Influence of a platelet GPIIb/IIIa receptor antagonist on myocardial hypoperfusion during rotational atherectomy as assessed by myocardial Tc-99m sestamibi scintigraphy.

OBJECTIVES: This study evaluated the effect of the glycoprotein IIb/IIIa (GPIIb/IIIa) antagonist abciximab on myocardial hypoperfusion during percutaneous transluminal rotational atherectomy (PTRA). BACKGROUND: PTRA may cause transient ischemia and periprocedural myocardial injury. A platelet-dependent risk of non-Q-wave infarctions after directional atherectomy has been described. The role of platelets for the incidence and severity of myocardial hypoperfusion during PTRA is unknown. METHODS: Seventy-five consecutive patients with complex lesions were studied using resting Tc-99m sestamibi single-photon emission computed tomography prior to PTRA, during, and 2 days after the procedure. The last 30 patients received periprocedural abciximab (group A) and their results were compared to the remaining 45 patients (group B). For semiquantitative analysis, myocardial perfusion in 24 left ventricular regions was expressed as percentage of maximal sestamibi uptake. RESULTS: Baseline characteristics did not differ between the groups. Transient perfusion defects were observed in 39/45 (87%) patients of group B, but only in 10/30 (33%) patients of group A (p < 0.001). Perfusion was significantly reduced during PTRA in 3.3 +/- 2.5 regions in group B compared to 1.4 +/- 2.5 regions in group A (p < 0.01). Perfusion in the region with maximal reduction during PTRA in groups B and A was 76 +/- 15% and 76 +/- 15% at baseline, decreased to 56 +/- 16% (p < 0.001) and 67 +/- 14%, respectively, during PTRA (p < 0.01 A vs. B), and returned to 76 +/- 15% and 80 +/- 13%, respectively, after PTRA. Nine patients in group B (20%) and two patients in group A (7%) had mild creatine kinase and/or troponin t elevations (p = 0.18). Patients with elevated enzymes had larger perfusion defects than did patients without myocardial injury (4.2 +/- 2.7 vs. 2.3 +/- 2.5 regions, p < 0.05). CONCLUSIONS: These data indicate that GPIIb/IIIa blockade reduces incidence, extent and severity of transient hypoperfusion during PTRA. Thus, platelet aggregation may play an important role for PTRA-induced hypoperfusion.

Abciximab↗
PubMed1999

Dual-head gamma camera 2-[fluorine-18]-fluoro-2-deoxy-D-glucose positron emission tomography in oncological patients: effects of non-uniform attenuation correction on lesion detection.

The purpose of this study was to evaluate a dual head coincidence gamma camera (DH-PET) equipped with single-photon transmission for 2-[fluorine-18]-fluoro-2-deoxy-D-glucose (FDG) imaging in oncological patients. Forty-five patients with known or suspected malignancies, scheduled for a positron emission tomography (PET) scan, were first studied with a dedicated ring PET and subsequently with DH-PET. All patients underwent measured attenuation correction using germanium-68 rod sources for ring PET and caesium-137 sources for DH-PET. Ring PET emission scan was started 64+/-17 min after intravenous administration of 235+/-42 MBq FDG. DH-PET emission followed 160+/-32 min after i.v. FDG. Attenuation-corrected and non-attenuation-corrected images were reconstructed for ring PET and DH-PET. The image sets were evaluated independently by three observers blinded to clinical data and to results of conventional imaging. Attenuation-corrected ring PET as the standard of reference depicted 118 lesions, non-attenuation-corrected ring PET 113 (96%) lesions, and attenuation-corrected DH-PET and non-attenuation-corrected DH-PET, 101 (86%) and 84 (71%) lesions, respectively (P<0.05). The lesion detection rate of attenuation-corrected and non-attenuation-corrected DH-PET was almost similar for lesions >20 mm, whereas attenuation correction increased the detection rate from 60% to 80% for lesions </=20 mm (P<0.01). A patient-based analysis revealed concordant results relative to attenuation-corrected ring PET for non-attenuation-corrected ring PET, attenuation-corrected DH-PET and non-attenuation-corrected DH-PET in 42 (93%), 36 (80%) and 31 (69%) patients, respectively. Differences might have influenced patient management in two (4%), six (13%) and ten (22%) patients, respectively. In conclusion, measured attenuation correction markedly improves the lesion detection capability of DH-PET. With measured attenuation correction the diagnostic performance of DH-PET is closer to that of dedicated ring PET.

Evaluation Studies as Topic↗
PubMed1999

"Ecstasy"-induced changes of cerebral glucose metabolism and their correlation to acute psychopathology. An 18-FDG PET study.

The aim of this study was to determine the acute effects of the "Ecstasy" analogue MDE (3,4-methylene dioxyethamphetamine) on cerebral glucose metabolism (rMRGlu) of healthy volunteers and to correlate neurometabolism with acute psychopathology. In a randomized double-blind trial, 15 healthy volunteers without a history of drug abuse were examined with fluorine-18-deoxyglucose (18FDG) positron emission tomography (PET) 110-120 min after oral administration of 2 mg/kg MDE (n = 7) or placebo (n = 8). Two minutes prior to radiotracer injection, constant cognitive stimulation was started and maintained for 32 min using a word repetition paradigm to ensure constant and comparable mental conditions during cerebral glucose uptake. Individual brain anatomy was represented using Tl-weighted 3D flash magnetic resonance imaging (MRI), followed by manual regionalization into 108 regions of interest and PET/MRI overlay. After absolute quantification of rMRGlu and normalization to global metabolism, normalized rMRGlu under MDE was compared to placebo using the Mann-Whitney U-test. Acute psychopathology was assessed using the Positive and Negative Syndrome Scale (PANSS) and rMRGlu was correlated to PANSS scores according to Spearman. MDE subjects showed significantly decreased rMRGlu in the bilateral frontal cortex: left frontal posterior (-7.1%, P < 0.05) and right prefrontal superior (-4.6%, P < 0.05). On the other hand, rMRGlu was significantly increased in the bilateral cerebellum (right: +10.1%, P < 0.05; left: +7.6%, P < 0.05) and in the right putamen (+6.2%, P < 0.05). There were positive correlations between rMRGlu in the middle right cingulate and grandiosity (r = 0.87, P < 0.05), both the right amygdala (r = 0.90, P < 0.01) and the left posterior cingulate (r = 0.90, P < 0.01) to difficulties in abstract thinking, and the right frontal inferior (r = 0.85, P < 0.05), right anterior cingulate (r = 0.93, P < 0.01), and left anterior cingulate (r = 0.85, P < 0.05) to attentional deficits. A negative correlation was found between the left frontal operculum (Broca's area) and attentional deficits (r = -0.85, P < 0.05). The present study revealed acute neurometabolic changes under the "Ecstasy" analogue MDE, indicating a frontostriatocerebellar imbalance paralleling other psychotropic substances or various psychiatric disorders.

3,4-Methylenedioxyamphetamine↗
PubMed1999

Preoperative PET activation for assessment of motor cortex area in precentral chondroma.

BACKGROUND: A main problem in the preoperative planning for precentral tumors is the exact assessment of the spatial relationship between the tumor and the functionally relevant brain areas, which may be difficult using only morphologically oriented imaging (CT, MRI). Therefore, we applied motor activation PET and PET/MRI overlay in a patient with a precentral tumor. DESCRIPTION: We report the case of a 21-year-old woman suffering from progressive right-sided headache and intermittent dysesthesia of the left leg. MRI showed a hypointense tumor with inhomogenous contrast enhancement in the right precentral area. For preoperative assessment of the spatial relationship between the tumor and the motor cortex area, the patient underwent two F-18-fluorodeoxyglucose positron emission tomography (PET) scans (1. resting condition and 2. motor activation of the left leg) and subsequent calculation of subtraction images of activation minus rest. Fusion of PET and MRI data (PET/MRI overlay) was performed for bimodal function and morphology presentation. PET revealed an activation pattern behind and below the tumor, indicating that the motor cortex area was shifted to the back. PET findings were confirmed by intraoperative electrophysiology. Cortical stimulation combined with intraoperative neuronavigation localized the motor area of the left foot and leg exactly at the dorsal border, below and lateral to the lesion. After complete resection of the solid tumor, histopathological examination revealed a chondroma. The postoperative course was uneventful, and the patient was discharged without neurological deficits. CONCLUSIONS: This case shows that biomodal imaging (PET/MRI) provides a noninvasive exact assessment of functionally important cortex areas for preoperative planning in patients with cerebral lesions.

Adult↗
PubMed1999

Does positron emission tomography using 18-fluoro-2-deoxyglucose improve clinical staging of testicular cancer?--Results of a study in 50 patients.

OBJECTIVES: To compare positron emission tomography (PET) using 18-fluoro-2-deoxyglucose (FDG) with conventional clinical staging in unselected patients with germ cell cancer. METHODS: Fifty patients underwent PET scans of the abdomen (n = 50) and chest (n = 41 ) after the initial diagnosis. PET images were evaluated qualitatively and quantitatively using standardized uptake values (SUVs). The results were compared with computed tomography (CT) results and tumor markers (human chorionic gonadotropin, alpha-fetoprotein, and lactate dehydrogenase). Retroperitoneal lymphadenectomy in 12 patients and clinical staging, including follow-up data in all patients, were taken as a reference standard. RESULTS: PET detected metastases in 13 (87%) of 15 patients and excluded metastases in 33 (94%) of 35 patients. A sensitivity of 73% and a specificity of 94% were obtained using CT. The respective values for tumor marker determination were 67% and 100%. Retroperitoneal metastases were detected in 2 patients by PET only and in 1 patient by CT only. In the latter patient, surgery of a residual mass after chemotherapy revealed a well-differentiated teratoma. False-negative findings with PET and CT occurred in 2 patients with retroperitoneal metastases approximately 10 mm in size. False-positive findings were due to sarcoidosis or to muscular activity of the neck. Quantitative FDG uptake was very heterogeneous, with an SUV ranging from 1.8 to 17.3. CONCLUSIONS: FDG PET has the potential to improve clinical staging of testicular cancer. However, PET, as well as CT, is limited in the detection of small retroperitoneal lymph node metastases.

Adult↗
PubMed1999

Radioiodine therapy in Graves' disease patients with large diffuse goiters treated with or without carbimazole at the time of radioiodine therapy.

We sought to ascertain how high the success rates of radioiodine therapy are for Graves' disease patients with large diffuse goiters when aiming for a constant absorbed dose of 250 Gy. Thirty-six patients with a thyroid volume of 50-110 mL were evaluated for changes in thyroid function and appearance 3, 6, and 12 months after radioiodine therapy. Success was defined as definitive elimination of hyperthyroidism following therapy (hypothyroidism corrected with thyroxine on diagnosis); failure as persistent/recurrent hyperthyroidism after 12 months. Overall success rate was 50%. However, a subgroup of 20 patients without simultaneous carbimazole (carbimazole-off) showed a highly significantly larger success rate (85%) than the 16 patients with simultaneous carbimazole (carbimazole-on) at the time of radioiodine therapy (6.3%, p < 0.000005). Successful cases showed a significantly higher volume reduction after radioiodine than failures (75.5% vs. 35.4%, p < 0.00005). Stepwise logistic regression showed that therapy failure was related to administration of carbimazole during radioiodine therapy (p < 0.0250 and absorbed dose (p < 0.05), but not thyroid function (free triiodothyronine [FT3] and free thyroxine [FT4]), initial thyroid volume or thyrotropin-receptor antibody (TRAb) value. However, a significant correlation of therapy success to absorbed dose (r = 0.69, p < 0.005) could be shown only for carbimazole-off patients, but not for the others. Finally, multivariate factor analysis consistently showed that therapy success was correlated only to absorbed dose and antithyroid drugs, not to initial thyroid volume, TRAb value, or thyroid function. Thyroid volume per se is not responsible for the lower success rate in Graves' disease patients with large goiters because even a comparable group of 32 Graves' disease patients with small thyroid glands (< or =20 mL) and without simultaneous carbimazole showed a success rate of 87.5%. The high failure rate in the carbimazole-on patients (absorbed dose comparable to carbimazole-off) is due to the simultaneous administration of carbimazole. Therefore, if clinically feasible, we recommend discontinuing carbimazole at least one day before beginning radioiodine therapy.

Adult↗
PubMed1999

Neuropsychological impairment correlates with hypoperfusion and hypometabolism but not with severity of white matter lesions on MRI in patients with cerebral microangiopathy.

BACKGROUND AND PURPOSE: Cerebral microangiopathy, indicated on MRI by lacunar infarctions (LI) and deep white matter lesions (DWML), is said to lead to vascular dementia. METHODS: Fifty-seven patients with proven cerebral microangiopathy were assessed for changes in regional cerebral blood flow (rCBF) and glucose metabolism (rMRGlu) and compared with 19 age-matched controls. The findings were correlated with results of extensive neuropsychological testing, as well as with MRI findings. A special head holder ensured reproducibility of positioning during rCBF (single-photon emission CT [SPECT]), rMRGlu (positron emission tomography [PET]), and MR imaging. White matter and cortex were quantified with regions of interest defined on MRI and superimposed to corresponding PET/SPECT slices. LI and DWML were graded by number and extent. RESULTS: Even with severe DWML and multiple LI, rCBF and rMRGlu values were not reduced. ANOVAs identified brain atrophy and neuropsychological deficits as the main determinants for reduced rCBF and rMRGlu values in both cortex and white matter. Neuropsychological deficits correlated well with decreased rCBF and rMRGlu, whereas MRI patterns such as LI and DWML did not. Factor analysis revealed no correlation of LI and DWML with rCBF, rMRGlu, atrophy, and neuropsychological deficits, showing instead positive correlations between rCBF, rMRGlu, and neuropsychological performance and negative correlations of the latter 3 with brain atrophy. CONCLUSIONS: From these data, we conclude that LI and DWML are epiphenomena that may morphologically characterize cerebral microangiopathy but do not in themselves indicate cognitive impairment. Dementia or neuropsychological deficits, by contrast, are reflected exclusively by functional imaging parameters (rCBF, rMRGlu) and cerebral atrophy.

Adult↗
PubMed1999

Success rate of radioiodine therapy in Graves' disease: the influence of thyrostatic medication.

There is controversy whether simultaneous thyrostatic medication influences the outcome of radioiodine (131I) therapy in Graves' disease by reducing the absorbed energy dose of 131I when delivering a standard dose. We therefore sought to ascertain whether the outcome of ablative 131I therapy is in any way affected by simultaneous thyrostasis (carbimazole) by aiming for a constant absorbed dose of 200-250 Gy. We prospectively studied 207 patients with Graves' disease (106 with and 101 without simultaneous carbimazole at the time of 131I therapy). All patients were reexamined 3, 6, and 12 months after 131I therapy. The 101 nonthyrostatic patients showed a highly significantly greater success rate (93%) than the 106 thyrostatic patients (49%). Stepwise logistic regression demonstrated that failure was related to the administration of carbimazole during 131I therapy (P < 0.00005) and the absorbed dose (P < 0.025), but was not related to free T3, free T4, TSH receptor antibodies, or thyroid volume. The success rate was 100% in 93 nonthyrostatic patients with absorbed doses of 200 Gy or more, but was only 12.5% (1 of 8) for absorbed doses less than 200 Gy. Correlation between success and absorbed dose was significantly higher for nonthyrostatic than for thyrostatic patients (r = 0.93 vs. r = 0.24). Sixteen patients who discontinued thyrostasis 1-3 days before 131I therapy showed 94% successes. Simultaneous thyrostasis is the decisive factor against a successful 131I therapy even if the significantly reduced 131I uptake/half-life values under thyrostasis are compensated with a higher delivered dose to ensure a comparable absorbed dose, possibly due to the additionally effective radioprotective properties of carbimazole. Therefore, if clinically feasible, we recommend discontinuing thyrostasis at least 1 day before beginning 131I therapy, because even in hyperthyroid nonthyrostatic patients the success rate was 100%.

Adult↗
PubMed1999

18FDG-positron emission tomography in pancreatic cancer.

UNLABELLED: POSITRON EMISSION TOMOGRAPHY: Malignant cells present an increased glucose consumption compared to normal pancreatic tissue. Positron emission tomography with 18F fluoro-D-deoxyglucose is a new imaging tool to in vivo assess the amount of glucose metabolism. This method provides metabolic information on tumors rather than morphological information. METHODS: In most PET centers a static emission scan of the upper abdomen is performed 45-60 minutes after intravenous administration of the radiotracer. To obtain quantitative parameter an additional transmission scan is necessary to correct for attenuation. Today, both visual analysis and semiquantitative parameters of glucose consumption as the Standardized Uptake Value (SUV) are used for image interpretation. To allow coregistration of the metabolic PET images and morphological imaging tools as CT or MRI external markers may be used. Following exact reorientation both the metabolic information (PET) and the morphologic information (MRI/CT) can be merged in one 3D data set (image fusion). RESULTS: In our series of patients the sensitivity for PET to detect pancreatic cancer was 85%, the specificity 84%. False negative results were obtained in patients with hyperglycemia, false positive results in patients with chronic active pancreatitis. Excluding hyperglycemic patients the sensitivity for PET increased to 98%. In a sample statistics of 305 euglycemic patients sensitivity, specificity and accuracy were 92%, 79%, and 87%, respectively. Image fusion of metabolic (PET) and morphologic data (MRI/CT) can help to better localize the focus of increased glucose consumption demonstrated with PET and to differentiate multifocal cancer from lymph node metastases. CONCLUSION: 18FDG PET is a feasible diagnostic modality to differentiate benign and malignant pancreatic masses when morphological imaging is equivocal. Image fusion of PET and CT or MRI can combine the advantages of both modalities in one image-detailed anatomic information combined with accurate metabolic data.

Fluorodeoxyglucose F18↗