Comparison of automated quantification and semiquantitative visual analysis findings of IQ SPECT MPI with conventional coronary angiography in patients with stable angina.

OBJECTIVE: The aim of this study was to assess the validity of automated quantitative and semiquantitative visual analysis of total perfusion deficit (TPD) using the IQ SPECT gamma camera system compared to conventional coronary angiographically detected significant coronary artery disease (CAD). METHODS: The study included patients with suspected CAD who underwent myocardial perfusion single photon emission computed tomography and conventional coronary angiography. The summed stress score (SSS), summed rest score (SRS), and summed difference score (SDS) (semiquantitative visual analysis results) were assessed using a 5-point scale in a standard 17-segment model, and TPD (stress, rest, and ischemic TPD) was quantified using automated software. RESULTS: In all, 84 patients (Group 1, those who underwent revascularization) had significant coronary artery lesions, and 81 (Group 2) had non-significant lesions. The median interquartile range values were: stress-TPD (sTPD): 16 (3.5- 33.5) vs 9.2 (2-17.9), rest-TPD: 9.4 (2.2-18.8) vs 4 (1-11), and 6.9 (1.9-14.1) vs 3.4 (1-6.1) for ischemic-TPD (iTPD) in Group 1 and Group 2, respectively. To detect ischemia, the optimal cut-off points were 9.5 (sensitivity: 75%, specificity; 60%) for sTPD, and 4.5 (sensitivity: 56%, specificity: 73%) for iTPD. There were significant correlations between quantitative and semi-quantitative methods in detection of significant coronary artery disease (sTPD-SSS: r=0.954, sTPD-SDS: r=0.746, iTPD-SSS: r=0.654, iTPD-SDS: r=0.759; p<0.05 for all). CONCLUSION: The quantitative analysis and summed stress scores produced by the IQ SPECT system appear to be a useful and valid method to detect significant CAD.

Clinical significance of standardized uptake values in thyroid incidentaloma discovered by F-18 fluorodeoxyglucose positron emission tomography/computed tomography.

AIM OF STUDY: While using F-18 fluorodeoxyglucose (FDG) positron emission tomography computed tomography (PET/CT) for other than thyroid disease, an increased frequency of incidentally discovered areas of focally or diffuse increased uptake within the thyroid gland can be seen. We aimed to find the focal thyroid FDG uptake and compare the maximum standardized uptake value (SUVmax) results with cytology and histology results. MATERIALS AND METHODS: We examined PET scan reports for all patients undergoing FDG PET/CT investigation over a 10-year period in a single center. Twelve thousand seven hundred and ninety-six patients underwent FDG PET/CT scanning in one PET/CT unit. Within this group, 526 patients had diffuse, focal, or multifocal FDG uptake. About 305 of 526 patients (57.9%) showed diffuse FDG uptake and 221 (42%) showed focal uptake on thyroid gland. RESULTS: The malignant group thyroid nodule sizes were between 8 and 39 mm (21.1 mm average, standard deviation [SD] ±7.3) on ultrasonography (USG) examination. These nodules have SUVmax values between 2.3 and 31.2 (average 8.8 SD ± 5.7). Benign group thyroid nodule sizes were between 5 and 46 mm (average 18.3 mm, SD ± 5.8) on USG examination. There were no significant correlations between SUVmax of the incidental focal thyroid lesions seen on FDG PET/CT and fine needle aspiration biopsy results. CONCLUSION: There is a relatively high possibility of a malignant lesion in thyroid incidentaloma. FDG uptake of these lesions is not a useful tool in absolute discrimination between malignancy and benign lesion. The presence of primary or secondary malign lesion is diagnosed in 34.1% of the patients who are found to have incidental focal FDG uptake within thyroid gland in PET/CT scans, but we suggest that the thyroid incidentalomas detected on FDG PET/CT should be further examined with USG and scintigraphy.

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.

Gallbladder metastasis secondary to gastric cancer as a first site of recurrence presented with acute cholecystitis: case report and literature review.

Metastasis to the gallbladder from other malignancies is extremely rare and is related with a very poor prognosis. Malignant melanoma has been reported to be the most common origin of gallbladder metastasis. Although only eight cases of gallbladder metastasis originating from gastric cancer have been documented in the literature based on small series, of these cases, only one case with signet ring cell carcinoma histology has been reported previously. We report the case of a 58-year-old male with early-stage signet ring cell carcinoma of the stomach who presented with acute cholecystitis previously treated with curative gastrectomy. After laparoscopic cholecystectomy, the diagnosis of gallbladder metastasis with signet ring cell histology secondary to gastric cancer was made. To our knowledge, this is only the second case of signet ring cell carcinoma of the stomach metastasized to the gallbladder as a first site of recurrence. We suggest that for patients with gastric cancer who complain of the findings of acute cholecystitis or cholecystolithiasis, gallbladder metastasis from gastric cancer should be considered in the differential diagnosis.