Diagnostic performance of 18F-FDG PET/contrast-enhanced CT versus contrast-enhanced CT alone for post-treatment detection of ovarian malignancy.

OBJECTIVE: The aim of this study was to evaluate the diagnostic performance of combined fluorine-18 fluorodeoxyglucose (F-FDG) PET/contrast-enhanced computed tomography (Ce-CT) in comparison with Ce-CT alone for the detection of residual/recurrent tumor after initial treatment of malignant ovarian tumors. PATIENTS AND METHODS: The study prospectively recruited 111 patients with a clinical suspicion of ovarian tumor recurrence. Each patient underwent F-FDG PET/computed tomography (CT) with low-dose CT, followed immediately by Ce-CT. Study-based analyses for a total of 136 scans were carried out. For each study, 11 subsites were assessed on a four-point score (score 0=definitely benign, score 1=probably benign, score 2=probably malignant, and score 3=definitely malignant). The subsites were collectively categorized into four groups: local tumor site, peritoneum, pelvi-abdominal lymph nodes, and other sites (e.g. liver, lung, bone, brain, etc). The final diagnosis of disease status was made on subsequent follow-up by conventional imaging (CT/MRI), F-FDG PET/CT, or histopathology whenever possible. RESULTS: Of the 136 studies evaluated, 97 (71%) studies had recurrent/residual disease and 39 (29%) studies were disease free on the basis of the final diagnosis. F-FDG PET/Ce-CT and Ce-CT had a sensitivity, specificity, negative predictive value, positive predictive value, and accuracy of 96 versus 84%, 92 versus 59%, 90 versus 59%, 97 versus 84%, and 95 versus 76%, respectively. F-FDG PET/Ce-CT was significantly more sensitive, specific, and accurate compared with Ce-CT, with P-values of 0.002, 0.001, and less than 0.0001, respectively. Site-based analyses also showed significant differences. CONCLUSION: CombinedF-FDG PET/Ce-CT significantly outperforms Ce-CT alone in the post-treatment detection of malignant ovarian tumors.

Comparison between low and high radioactive iodine (131I) reablation dose in patients with papillary thyroid cancer.

AIM: The aim of this study was to assess ablation outcome after a second ablation dose and compare the ablation rate after low and high reablation doses of iodine-131 ((131)I) after failure of the first ablation with 3700 MBq. PATIENTS AND METHODS: The study included 81 patients with papillary thyroid cancer; they failed to achieve complete ablation after a first ablative dose of 3700 MBq. Their first follow-up (131)I whole-body scan carried out 6-9 months after ablation showed small residual functioning tissue in the thyroid bed, with no functioning metastases. This is associated with unsuppressed serum thyroglobulin level (Tg) higher than 2 ng/ml. The patients received a second ablation dose, which was low (1110 MBq) in 37 patients and high in the remaining 44 patients (2960 MBq in 36 patients and 3700 MBq in eight patients). A whole-body scan and Tg level assessment were carried out 6-9 months later. The criteria for complete ablation included absence of residual functioning thyroid tissue and a Tg level lower than 2 ng/ml. RESULTS: The overall successful complete ablation rate after the second reablation dose was 75%. This was achieved in 27 of 37 patients (73%) who received a low reablation dose and in 34 of 44 patients (77%) who received a high reablation dose; no statistically significant difference was found between the two groups (P>0.05). CONCLUSION: In patients with papillary thyroid cancer who failed to achieve complete ablation after the first ablation dose of 3700 MBq, the overall complete ablation rate after both a low and a high second (131)I dose was 75%, with no statistically significant difference in ablation rate between low (1110 MBq) and high (2960 and 3700 MBq) doses (73 and 77%, respectively).

Utility of left lateral supine position for myocardial perfusion single-photon emission computed tomography compared with other methods of correcting inferior wall attenuation.

INTRODUCTION: Single-photon emission computed tomography (SPECT) myocardial perfusion imaging is an accepted method for reflecting the pathophysiological significance of lesions detected by coronary angiography. However, it has an inherent drawback in terms of false-positive perfusion defects for the inferior myocardial wall. To overcome this problem, different acquisition techniques have been proposed, including the computed tomographic-based attenuation correction method. In this respect, a new imaging technique, left supine lateral position SPECT myocardial perfusion imaging with technetium-99m methoxyisobutylisonitrile (Tc-99m MIBI), has been proposed to eliminate this problem and its value has been investigated in this report. MATERIALS AND METHODS: Sixty-two patients were prospectively and randomly enrolled in this study. They underwent Tc-99m MIBI SPECT in the supine, prone, left lateral, and sitting positions after an adequate stress test on the same day.The presence and extent of defects on stress images were noted in the supine image data set for the 11 myocardial segments, which were then labeled as 1 or 0 if a defect was present or absent, respectively. This evaluation sequence was repeated in all other image data sets. When defects persisted in other scan positions it was regarded as true positive, and when they were resolved they were regarded as false positive. By this means, the percentages of resolving perfusion defects by that imaging position were calculated for each observer per positional pair under comparison. RESULTS: From six interpretations carried out by the nuclear medicine physicians, 6×11×3=198 four-fold tables in 11 segments were analyzed for discrepancies between position pairs. In 31 of 33 discrepant interpretations, defects observed in any of the other positions were resolved in the lateral position. Only in two evaluations of one observer were the discrepancies against lateral positioning for the anterior wall. If the inferior wall was considered alone, it was clearly obvious that lateral positioning was more accurate than the other positions.Intraobserver evaluation showed the methodology to be highly reproducible.The SPECT findings were concordant with coronary angiography results in selected patients. CONCLUSION: Visual and quantitative evaluations of the variation in inferior wall activity lead us to suggest that SPECT imaging with Tc-99m MIBI be performed in the left lateral position to allow better visualization of the inferior and septal walls in those departments not able to utilize computed tomographic attenuation correction.

Impact of histopathology of non-neoplastic thyroid tissue on ablation outcome in patients with papillary thyroid cancer.

OBJECTIVE: To assess the impact of histopathology of non-neoplastic thyroid tissue on ablation outcome in patients with papillary thyroid cancer (PTC). METHODS: The study included 124 patients referred for I-131 ablation therapy after total thyroidectomy for unifocal nonmetastatic PTC. All patients received 100 mCi of I-131 ablation dose. Follow-up whole body scan (WBS) and estimation of serum thyroglobulin level were carried out 6-9 months after ablation therapy and results were divided into complete or incomplete ablation. RESULTS: Incomplete ablation was found in 66.6% (12 of 18), 64% (16 of 25), 39.1% (nine of 23), 30% (six of 20), 33% (six of 18), and 20% (four of 20) in patients with PTC in a background of Hashimoto's thyroiditis, lymphocytic thyroiditis, colloid nodular goiter, nodular hyperplasia, multinodular goiter, and normal thyroid tissue, respectively. Patients with Hashimoto's thyroiditis and lymphocytic thyroiditis had statistically significant higher failure rate to achieve complete ablation compared with other groups. This significant difference was lacking between different nonautoimmune histopathologies and normal thyroid tissue. For patients with thyroid disorders of autoimmune origin (Hashimoto's thyroiditis and lymphocytic thyroiditis), incomplete ablation was found in 65.1% (28 of 43) versus 34.4% (21 of 61) for all other nonautoimmune histopathologies collectively; the difference was statistically significant. CONCLUSION: Histopathology of non-neoplastic thyroid tissue has a significant impact on ablation outcome in patients with PTC. Patients with a histopathology of non-neoplastic thyroid tissue of autoimmune origin have a significantly lower incidence of successful complete ablation after a single I-131 ablative dose (100 mCi) compared with those with nonautoimmune histopathology or with normal thyroid tissue.

Silent central nervous system involvement in Egyptian Behçet's disease patients: clinical, psychiatric, and neuroimaging evaluation.

Behçet's disease (BD) is an idiopathic multisystem disorder. Involvement of CNS occurs in 4-48% of cases. This study was designed to evaluate the prevalence of subclinical neuropsychiatric affection in asymptomatic Egyptian BD patients using psychometric tests and brain imaging with single photon emission computed tomography (SPECT) and magnetic resonance imaging (MRI), also to assess possibly associated clinical predictive variables. Twenty-five BD patients without overt CNS involvement and ten healthy controls matched for age, education, and sex completed a comprehensive neuropsychological battery including Hamilton scales for anxiety and depression and Wechsler memory scale-revised. Disease activity was assessed using Behçet's Disease Current Activity Form (BDCAF). SPECT was done for all subjects, and 12 patients underwent brain MRI. Compared to controls, 23 (92%) and 24 (96%) patients had anxiety and depression scores respectively above normal range; also, BD patients had significantly lower memory quotient (MQ). SPECT revealed abnormalities in 16/25 (64%), while in 3/12 patients (25%), MRI was abnormal. Subjects with abnormal SPECT had significantly higher ages than those with normal SPECT (P = 0.02) and were more frequently males (P = 0.03). No statistically significant differences between cases with normal or abnormal SPECT were found regarding disease duration, frequency of headache, BDCAF, frequency of active eye disease, major vascular involvement, mean Hamilton anxiety and depression scores, and mean MQ. Early diagnosis of neurological involvement in BD is important in reducing or preventing complications. Neuropsychiatric evaluation and HMPAO brain SPECT were found to be useful for detecting subclinical neurological abnormalities in BD patients.

Long-term carbimazole intake does not affect success rate of radioactive 131Iodine in treatment of Graves' hyperthyroidism.

OBJECTIVE: The aim of this study is to assess the effect of long-term antithyroid drug intake on the success rate of iodine-131 (131I) treatment of Graves' hyperthyroidism, and to explore other clinical/laboratory factors that may predict/affect the treatment outcome. MATERIALS AND METHODS: Fifty-eight patients with Graves' disease were referred for radioactive iodine therapy after failure of medical treatment, which was given for at least 6 months. Antithyroid drug (carbimazole) was stopped for at least 2 days before administration of a fixed dose of 370 MBq. Treatment outcome was determined at the end of 1-year follow-up after iodine administration. Treatment success was reported if the thyroid hormonal profile indicated euthyroid or hypothyroid state. RESULTS: One year after 131I administration, 19% of our patients were still hyperthyroid (treatment failure), 15.5% became euthyroid and 65.5% were hypothyroid (treatment success, 81%). No statistically significant correlation was found between treatment outcome and patient's age at the time of I administration (P=0.20); duration of medical treatment before 131I administration (P=0.22) and duration of stoppage of medical treatment before 131I intake (P=0.15). In contrast, there was significant association between treatment outcome and pretreatment Tc99m-thyroid uptake (P=0.0001), thyroid size (P=0.001) and TSH level (P=0.04). Using receiver operator characteristic curve analysis, we generated a cut-off value for thyroid uptake (18%) and thyroid weight (70 g) to predict response to 370 MBq of 131I. The 18% thyroid uptake cut-off value predicted treatment outcome with 93.6% sensitivity, 100% specificity and 94.8% accuracy, whereas the 70 g thyroid weight predicted treatment outcome with sensitivity, specificity and accuracy of 80.9, 72.7 and 79.3%, respectively. CONCLUSION: Long-term carbimazole treatment will not increase the failure rate of 131I treatment in patients with Graves' disease if the drug was discontinued for at least 2 days before iodine administration. A fixed dose of 370 MBq is efficient in patients with Tc99m-pertechnetate thyroid uptake less than 18% and gland weight less than 70 g. Patients with larger goitres and/or higher thyroid uptake level will probably need a higher dose of radioactive iodine.