Thyroid uptake versus thyroid salivary ratios: which is more reliable for post-operative thyroid functional assessment in patients with recurrent hyperthyroidism?

Tc-99m pertechnetate thyroid uptake has been introduced as a useful adjunct to measurement of hormonal levels in patients with recurrent hyperthyroidism after surgery for toxic goiter. A crude but relatively accurate estimate of thyroid function can be obtained by comparing thyroid to salivary gland activity at 20 minutes. We aimed in the current study to assess the value of Tc-99m pertechnetate thyroid uptake [TU] and thyroid-salivary ratios [both thyroid/salivary ratio: TSR and salivary/thyroid ratio; STR] in diagnosis of post-operative recurrent hyper-functioning thyroid tissue. The current study included 114 patients presented for thyroid scintigraphy 3-9 months post subtotal thyroidectomy for toxic goiter [73 Grave's disease and 41 toxic nodular goiter]. Ten patients proved to have hypothyroidism were excluded from the study. All patients were subjected to clinical history and examination, thyroid hormonal profile, Tc-99m pertechnetate thyroid scan with calculation of TU, TSR and STR 20mjn after injection of the radiotracer. Thyroid uptake per unit weight of residual thyroid tissue was also calculated. TU value was considered normal if it is in the range of 0.3 to 3.75%.According to thyroid hormonal profile, patients were divided into two main groups, Group 1: Included 25 patients with hyperthyroid state. The mean value of TU was 10.2%. The mean value of TSR and STR were 11.75 and 11.1%. Twenty-three patients had both indices pointing to hyperthyroidism. The sensitivity of the thyroid uptake value for diagnosis of hyperthyroidism in this group of patients was 68%, while the sensitivity for both TSR and STR was 92%, with a statistically significant difference between both figures [p<0.001]. Group 2: Included the remaining 79 patients with normal thyroid hormonal profile. Their mean uptake value was 1.58%, while the mean value of TSR and STR were 2.5% and 57%. All patients in this group had normal thyroid uptake level. The specificity of TU for diagnosis of recurrent hyperthyroidism was 100%. versus 97.5% for both TSR and STR. The mean thyroid uptake per unit weight of residual thyroid tissue in group 2 was 6.4, which is significantly less than that reported for group 1 [19.5%] [p<0.001]. Thyroid uptake value has lower sensitivity [68%] than thyroid salivary ratios [TSR and STR] [92%] in diagnosis of post-operative recurrent hyperthyroidism with comparable specificity. So, TSR and STR are more reliable than Tc-99m pertechnetate TU in diagnosis of recurrent hyperthyroidism post operatively and may be applied in this group of patients for assessment of the functional status of residual thyroid tissue. Thyroid uptake per unit weight of remaining thyroid tissue is significantly higher for recurrent toxic state compared to euthyroid state; this may represent a new useful functional index, warranting further randomized study on much larger number of patients to verify its exact value

Myocardial perfusion scintigraphy [Gated-SPECT] and coronary disease risk factors in Behcet's disease with metabolic syndrome

Behcet's disease [BD] is a multi-system vasculitis that can have a wide range of effects on the cardiovascular system. To determine the existence of myocardial perfusion defects caused by coronary microvascular dysfunction in asymptomatic BD patients with and with out metabolic syndrome and to evaluate coronary arterial distribution and left ventricular systolic function by gated single-photon emission computed tomography [G-SPECT]. The study population consisted of 20 [17 men and 3 women] patients with BD and 20 healthy controls of age and sex match. Technetium-99m methoxyisobutylisonitrile [Tc-99m MIBI] gated SPECT studies were performed using a 1-day rest-stress protocol. Stress and rest left ventricular ejection fraction [LVEF] were calculated. Using gated SPECT images myocardial perfusion scores [summed stress score [SSS], summed rest score [SRS] and summed difference score [SDS]] were determined. Echocardiography was performed for comparison. Carotid intima-media thickness [1MT] was recorded to detect the macrovascular involvement in BD and to detect if there is any possible correlation with the microvascular myocardial affection. Abnormal myocardial perfusion scintigraphy [MRS] was detected in 15 patients [2 with infarction, 13 with perfusion defects], 5 patients had normal perfusion pattern. Scmiquantitative scores [SSS, SRS and SDS] were significantly higher in the BD patients compared to control [p 0.000]. There was a statistically significant difference between BD patients and control regarding the carotid artery IMT by ultrasonography being increased in the patients. On the other hand, the G-SPECT and echocardiographic LVEF was significantly lower in the BD patients [p 0.001 and p 0.002 respectively]. On comparing the results of the BD patients with and without metabolic syndrome, the studied parameters for coronary risk factors as blood pressure, cholesterol, triglycerides and fasting blood sugar they were significantly higher in the metabolic syndrome group. On the other hand, the HDE was significantly lower in the metabolic syndrome group. Both the disease activity [BDCAF] and the myocardial perfusion gated SPECT [SSS] were significantly higher in those BD patients with metabolic syndrome [p 0.03]. On the contrary, the differences in results of the carotid artery IMT and the echocardiographic LVEF% in BD patients with and without metabolic syndrome did not reach significance. There was a tendency to increased disease duration in BD patients with more severe myocardial perfusion defect. The difference was only significant between patients with perfusion defect and those with old myocardial infarction involving the antero-septal wall [p 0.04]. There was a statistically significant difference among the three myocardial perfusion scan subgroups as regards the level of triglycerides, systolic and diastolic blood pressure [p 0.29, 0.38, 0.13 respectively]. The CRP level was higher in the infarct patients followed by the defective perfusion. A significant difference was only found when comparing the level of those with history of infarction [severe ischemia] with those with normal myocardial perfusion scan [p 0.047]. On comparing the carotid artery IMT, echocardiographic LVEF%, and myocardial perfusion G-SPECT parameters, they were all significantly different among BD patients with infarction, defective and normal myocardial perfusion. A significant positive correlation was present between the SRS and the disease duration [p 0.04]. CRP significantly correlated with both the SSS and SDS [p 0.04 and 0.00 respectively]. Furthermore, the SSS and SRS significantly correlated with the blood pressure, triglycerides and cholesterol levels. The BDCAF significantly correlated with the SSS and SDS [p 0.009 and 0.007 respectively]. Carotid artery IMT significantly correlated only with SRS [0.02]. However, the echocardiographic LVEF% significantly correlated with all the myocardial perfusion gated SPECT parameters. Myocardial perfusion and function are disturbed owing to influenced coronary microvascularity in BD with silent myocardial ischemia [SMI]. Gated SPECT is a non-invasive more reliable method compared to echocardiography that simultaneously evaluates the existence, extent and severity of myocardial ischemia or infarction in cardio-Behcet. Myocardial perfusion defects increase with increased disease activity and carotid artery IMT. Metabolic syndrome risk factors account for an augmented perfusion defect and should be considered a high risk group in BD patients