A robust computational solution for automated quantification of a specific binding ratio based on [123i]fp-cit SPECT images.

AIM: The purpose of the current paper is to present a computational solution to accurately quantify a specific to a non-specific uptake ratio in [123I]fP-CIT single photon emission computed tomography (SPECT) images and simultaneously measure the spatial dimensions of the basal ganglia, also known as basal nuclei. A statistical analysis based on a reference dataset selected by the user is also automatically performed. METHODS: The quantification of the specific to non-specific uptake ratio here is based on regions of interest defined after the registration of the image under study with a template image. The computational solution was tested on a dataset of 38 [123I]FP-CIT SPECT images: 28 images were from patients with Parkinson's disease and the remainder from normal patients, and the results of the automated quantification were compared to the ones obtained by three well-known semi-automated quantification methods. RESULTS: The results revealed a high correlation coefficient between the developed automated method and the three semi-automated methods used for comparison (r ≥0.975). The solution also showed good robustness against different positions of the patient, as an almost perfect agreement between the specific to non-specific uptake ratio was found (ICC=1.000). The mean processing time was around 6 seconds per study using a common notebook PC. CONCLUSION: The solution developed can be useful for clinicians to evaluate [123I]FP-CIT SPECT images due to its accuracy, robustness and speed. Also, the comparison between case studies and the follow-up of patients can be done more accurately and proficiently since the intra- and inter-observer variability of the semi-automated calculation does not exist in automated solutions. The dimensions of the basal ganglia and their automatic comparison with the values of the population selected as reference are also important for professionals in this area.

Effect of hormone replacement on exercise cardiopulmonary reserve and recovery performance in subclinical hypothyroidism.

Subclinical hypothyroidism (SH) patients present cardiopulmonary, vascular and muscle dysfunction, but there is no consensus about the benefits of levothyroxine (L-T4) intervention on cardiopulmonary performance during exercise. The aim of the present study was to investigate the effects of L-T4 on cardiopulmonary exercise reserve and recovery in SH patients. Twenty-three SH women, 44 (40-50) years old, were submitted to two ergospirometry tests, with an interval of 6 months of normalization of thyroid-stimulating hormone (TSH) levels (L-T4 replacement group) or simple observation (TSH = 6.90 µIU/mL; L-T4 = 1.02 ng/dL). Patients with TSH >10 µIU/mL were excluded from the study to assure that they would receive treatment in this later stage of SH. Twenty 30- to 57-year-old women with no thyroid dysfunction (TSH = 1.38 µIU/mL; L-T4 = 1.18 ng/dL) were also evaluated. At baseline, lower values of gas exchange ratio reserve (0.24 vs 0.30; P < 0.05) were found for SH patients. The treated group presented greater variation than the untreated group for pulmonary ventilation reserve (20.45 to 21.60 L/min; median variation = 5.2 vs 25.09 to 22.45 L/min; median variation = -4.75, respectively) and for gas exchange ratio reserve (0.19 to 0.27; median variation = 0.06 vs 0.28 to 0.18; median variation = -0.08, respectively). There were no relevant differences in cardiopulmonary recovery for either group at baseline or after follow-up. In the sample studied, L-T4 replacement improved exercise cardiopulmonary reserve, but no modification was found in recovery performance after exercise during this period of analysis.

Effect of hormone replacement on exercise cardiopulmonary reserve and recovery performance in subclinical hypothyroidism

Subclinical hypothyroidism (SH) patients present cardiopulmonary, vascular and muscle dysfunction, but there is no consensus about the benefits of levothyroxine (L-T4) intervention on cardiopulmonary performance during exercise. The aim of the present study was to investigate the effects of L-T4 on cardiopulmonary exercise reserve and recovery in SH patients. Twenty-three SH women, 44 (40-50) years old, were submitted to two ergospirometry tests, with an interval of 6 months of normalization of thyroid-stimulating hormone (TSH) levels (L-T4 replacement group) or simple observation (TSH = 6.90 μIU/mL; L-T4 = 1.02 ng/dL). Patients with TSH >10 μIU/mL were excluded from the study to assure that they would receive treatment in this later stage of SH. Twenty 30- to 57-year-old women with no thyroid dysfunction (TSH = 1.38 μIU/mL; L-T4 = 1.18 ng/dL) were also evaluated. At baseline, lower values of gas exchange ratio reserve (0.24 vs 0.30; P < 0.05) were found for SH patients. The treated group presented greater variation than the untreated group for pulmonary ventilation reserve (20.45 to 21.60 L/min; median variation = 5.2 vs 25.09 to 22.45 L/min; median variation = -4.75, respectively) and for gas exchange ratio reserve (0.19 to 0.27; median variation = 0.06 vs 0.28 to 0.18; median variation = -0.08, respectively). There were no relevant differences in cardiopulmonary recovery for either group at baseline or after follow-up. In the sample studied, L-T4 replacement improved exercise cardiopulmonary reserve, but no modification was found in recovery performance after exercise during this period of analysis.

Effect of levothyroxine replacement on exercise performance in subclinical hypothyroidism.

Although muscle metabolism and exercise capacity seem to be affected in patients with subclinical hypothyroidism, there is little evidence indicating improvement of the exercise tolerance due to levothyroxine (L-T(4)) replacement. The aim of the present study was to verify possible cardiopulmonary changes during exercise in patients with subclinical hypothyroidism on L-T(4) replacement with a normal serum TSH for six months. Twenty-three patients with subclinical hypothyroidism were randomized into treated (no.=11) and untreated (no.=12) patients. A cardiopulmonary test was performed with a treadmill, using the modified Balke protocol. Heart rate, oxygen uptake, minute ventilation and other cardiopulmonary parameters were assessed at the 5th minute of exercise. FT4 levels increased while TSH normalized after hormone replacement. Oxygen uptake decreased significantly after hormone replacement (24.1+/-6.3 vs 17.1+/-4.2 ml x kg x min(-1); p=0.03).Minute ventilation also showed an enhanced performance in treated patients (28.0+/-8.1 vs 23.5+/-5.6 l x min(-1); p=0.03), as did the heart rate (128+/-17 vs 121+/-17 bpm; p=0.03). There were no changes in the untreated group. The results demonstrate that submaximal cardiopulmonary exercise performance improved after six months of TSH normalization and this improvement can help enhance the ability to carry out daily life activities in patients with subclinical hypothyroidism.

Gas exchange during exercise in different evolutional stages of chronic Chagas' heart disease.

OBJECTIVE: To compare gas exchange at rest and during exercise in patients with chronic Chagas' heart disease grouped according to the Los Andes clinical hemodynamic classification. METHODS: We studied 15 healthy volunteers and 52 patients grouped according to the Los Andes clinical and hemodynamic classification as follows: 17 patients in group IA (normal electrocardiogram and echocardiogram), 9 patients in group IB (normal electrocardiogram and abnormal echocardiogram), 14 patients in group II (abnormal electrocardiogram and echocardiogram, without congestive heart failure), and 12 patients in group III (abnormal electrocardiogram and echocardiogram with congestive heart failure). The following variables were analyzed: oxygen consumption (V O2), carbon dioxide production (V CO2), gas exchange rate (R), inspiratory current volume (V IC), expiratory current volume (V EC), respiratory frequency, minute volume (V E), heart rate (HR), maximum load, O2 pulse, and ventilatory anaerobic threshold (AT). RESULTS: When compared with the healthy group, patients in groups II and III showed significant changes in the following variables: V O2 peak, V CO2 peak, V IC peak, V EC peak, E, HR, and maximum load. Group IA showed significantly better results for these same variables as compared with group III. CONCLUSION: The functional capacity of patients in the initial phase of chronic Chagas' heart disease is higher than that of patients in an advanced phase and shows a decrease that follows the loss in cardiac-hemodynamic performance.