Interobserver and Intraobserver Variability among Measurements of FDG PET/CT Parameters in Pulmonary Tumors.

BACKGROUND: 18F-fluorodeoxyglucose (FDG) positron emission tomography computed tomography (PET/CT) provides information about metabolic and morphologic status of malignancies. Tumor size and standardized uptake value (SUV) measurements are crucial for cancer treatment monitoring. AIMS: The purpose of our study was to assess the variability of these measurements performed by observers evaluating lung tumors. STUDY DESIGN: Retrospective cross-sectional study. METHODS: FDG PET/CT images of 97 patients with pulmonary tumors were independently evaluated by two experienced nuclear medicine physicians. Primary tumor size (UDCT), maximum SUV (SUVmax), mean SUV (SUVmean) and maximum SUV normalized to liver mean SUV (SUVnliv max) were measured by each observer at two different times with an interval of at least 2 weeks. Interobserver and intraobserver variabilities of measurements were evaluated through statistical methods. RESULTS: Size of the lesions varied from 0.81 to 13.6 cm (mean 4.29±2.24 cm). Very good agreement was shown with correlation, Bland-Altman and regression analysis for all measured PET/CT parameters. In the interobserver and intraobserver variability analysis, the Pearson correlation coefficients were greater than 0.96 and 0.98, respectively. CONCLUSION: Semi-quantitative measurements of pulmonary tumors were highly reproducible when determined by experienced physicians with clinically available software for routine FDG PET/CT evaluation. Consistency may be improved if the same observer performs serial measurements for any one patient.

Role of 18F-fluorodeoxyglucose Positron Emission Tomography/Computed Tomography in the Evaluation of Cytologically Indeterminate Thyroid Nodules.

BACKGROUND: Thyroid nodules with indeterminate fine-needle aspiration biopsy (FNAB) results remain a diagnostic dilemma, because 70 - 85% of these nodules have been found to be benign after thyroid surgery. OBJECTIVES: The purpose of this study was to evaluate the usefulness of 18F-fluorodeoxyglucose (FDG) positron emission tomography/computed tomography (PET/CT) in the preoperative diagnosis of cytologically indeterminate nodules. PATIENTS AND METHODS: Forty-six patients were included in this study. These individuals had undergone FDG PET/CTs for the preoperative evaluation of thyroid nodules with indeterminate FNAB results. The results of the preoperative PET/CT scans were compared with the postoperative pathological results and statistically analyzed. RESULTS: Of the 46 patients included in our study, the histopathology of the surgical specimens revealed thyroid cancer in 17 individuals (37%, 17/46). The PET/CT scan showed a positive result in 27 patients. Of these, 16 patients (59.3%) were found to have thyroid carcinomas. In addition, the PET/CT scan was considered to be negative in 19 patients, 18 (94.7%) of whom had benign lesions. For the detection of malignant lesions, the values for the sensitivity and specificity, and the positive predictive and negative predictive values were 94%, 62%, 59%, and 95%, respectively. CONCLUSION: The FDG PET/CT showed a high sensitivity and a high negative predictive value for identifying malignancies in thyroid nodules with indeterminate FNAB results. Therefore, the FDG PET/CT may be a helpful tool in the clinical management of these nodules. When an FDG positive lesion is detected, further examination is recommended.

The value of 18F-fluorodeoxyglucose positron emission tomography/computed tomography in carcinoma of an unknown primary: diagnosis and follow-up.

BACKGROUND: The management of the patients with carcinoma of an unknown primary represents a difficult challenge in oncology. 18F-fluorodeoxyglucose positron emission tomography/computed tomography (FDG PET/CT) has provided new insights in the diagnosis, staging, and follow-up of oncological patients. AIM: This study aimed to investigate the value of FDG PET/CT in clarifying the primary site in our patients with histologically proven tumor metastasis (HPM) or with a high clinical suspicion of malignancy, and the clinical impact of this technique on the management of these patients. METHODS: In total 94 patients from two centers underwent FDG PET/CT imaging; 78 patients with HPM and 16 patients with a clinical suspicion of malignancy. The histology and/or follow-up data were used as the gold standard. Hypermetabolic findings at the site of the pathological CT changes or at physiological FDG uptake sites were the criteria for malignancy. PET/CT findings were analyzed for the identification of the primary tumor site, for the relationship with survival, and also for the effect in chemotherapy monitoring. RESULTS: Primary malignancy was discovered in 53 of 90 patients (59%) histologically and 37 (41%) patients' primary tumor sites were not found during the study period. Amongst 90 patients, five (6%) were normal on FDG PET/CT. Of 85 patients (94%) with pathological findings on FDG PET/CT, 27 patients (32%) had solitary and 58 (68%) patients had multiple organs affected. Regarding the whole study population, a sensitivity of 74% and a specificity of 78% were calculated for FDG PET/CT imaging. Regarding the patients with HPM, the sensitivity and specificity values were 84 and 81%, respectively. The mean survival time of the patients with disseminated disease was significantly shorter than those of the patients with single or no lesion (13.44+/-1.61, 20.98+/-2.0 and 26.67+/-2.73 months, respectively, P=0.014). In seven of eight patients, follow-up FDG PET/CT scans effectively monitored the patients' therapies. CONCLUSION: Whole-body FDG PET/CT has to be considered a useful method, especially in an early phase of the diagnostic workup of patients with carcinoma of an unknown primary syndrome, to optimize the management.

Tc-99m MIBI uptake in traumatic vertebral fractures and metastatic vertebral lesions: comparison with Tc-99m MDP.

This study compared technetium-99m-hexakis-2-methoxyisobutyl-isonitrile (Tc-99m MIBI) with technetium-99m methylene iphosphonate (Tc-99m MDP) to determine whether Tc-99m MIBI could distinguish vertebral metastases from traumatic vertebral fractures. Twenty patients with traumatic vertebral fracture (and no malignant disease) and 14 patients with metastatic vertebral lesions were evaluated. Three to 4 hours after intravenous injection of Tc-99m MDP, images of the vertebrae in all patients were obtained. Corresponding Tc-99m MIBI images were acquired within 4 days after the Tc-99m MDP bone images were obtained. Computed tomography and magnetic resonance imaging demonstrated 24 vertebral traumatic fractures and 44 vertebral metastases. On conventional bone scans, Tc-99m MDP activity was increased in 92% of vertebral fractures and in 100% of vertebral metastases. However, on MIBI scans, no abnormal findings were observed in the vertebrae with fracture, although increased activity was seen in 73% of vertebral metastases. In this study, traumatic vertebral fractures tended to display no pathologic increases in Tc-99m MIBI uptake, whereas bone metastases usually appeared with high uptake. In light of the excellent specificity of Tc-99m MIBI scans compared with Tc-99m MDP bone scans, imaging studies that use Tc-99m MIBI scans may play an important complementary role in differentiating vertebral metastases from traumatic vertebral fractures.

Evaluation of vascularized graft reconstruction of the mandible with Tc-99m MDP bone scintigraphy.

AIM: The aim of this study was to evaluate the value of bone scintigraphy for the assessment of graft viability following vascularized bone grafts in patients with mandibular reconstruction. METHODS: We investigated 16 patients with vascularized grafts from the fibula (13 patients) and iliac crest (3 patients) in the last 8 years. For the follow up of all these patients, Tc-99m MDP bone scintigraphy was performed between 2-10 days postoperatively. SPECT study was included in 5 patients. For the evaluation of the grafts, a six-grade scoring system was used. The grading system was based on a comparison of tracer uptake between graft and the cranium. The uptake was defined as increasing from grade 6 to grade 1. RESULTS: Thirteen of the 16 grafts had an uncomplicated clinical course. Complications in the graft occurred in three patients. In the analysis of planar scintigrams, patients with uncomplicated healing showed increased uptake in 12 of the 13 grafts (grade 1-3) and 1 showed the same level tracer uptake compared to cranium (grade 4). In the failed 3 grafts, decreased uptake was observed (grade 5 and 6). In 5 patients, SPECT was performed in addition to planar imaging. In these patients, 4 of the 5 grafts had an uncomplicated clinical course and 1 had a complicated one. In the analysis of SPECT images, while all the grafts with an uncomplicated clinical course exhibited increased uptake (grade 1-3), the failed graft showed decreased uptake (grade 6). CONCLUSION: Three-phase bone scintigraphy performed within 10 days after the mandibular reconstruction is a useful tool to monitor the viability and early complications of vascularized mandibular bone grafts. SPECT is also recommended. It may contribute to interpretation of the bone scans and to precise assessment of graft viability.

Role of technetium-99m N,N-ethylenedicysteine renal scintigraphy in the evaluation of differential renal function and cortical defects.

PURPOSE: This study was performed to evaluate the effectiveness of technetium-99m N,N-ethylenedicysteine (Tc-99m EC) in comparison to technetium-99m dimercaptosuccinic acid (Tc-99m DMSA) scintigraphy. Differential renal function (DRF) was calculated by both methods and the cortical-phase images of dynamic Tc-99m EC scintigraphy were evaluated for parenchymal defects. MATERIALS AND METHODS: A total of 62 patients with various kidney disorders ranging in age from 1 to 44 years underwent both Tc-99m DMSA and Tc-99m EC scintigraphy. Tc-99m EC summed images of the cortical phase and Tc-99m DMSA images were evaluated visually and quantitatively. Visual analysis was used to define renal parenchymal abnormalities. Quantitative analysis was used in the calculation of DRF. The Tc-99m DMSA scan was taken as the gold standard, and the summed Tc-99m EC scan findings were compared against it. RESULTS: The images obtained with Tc-99m DMSA and Tc-99m EC scintigraphy revealed 99 and 97 focal defects, respectively. The 2 renal parenchyma defects located in the ventral middle sections remained undetected with Tc-99m EC scintigraphy. DRF of the kidneys in each patient was compared using both radiopharmaceuticals. Highly positive correlation between the differential function of these 2 investigations was found (R = 0.91, P = 0.001). The values of mean DRF of the left kidney on Tc-99m EC and Tc-99m DMSA images were 45.8 +/- 19.1 and 45.0 +/- 20.4, respectively. There were no significant differences (P > 0.05). CONCLUSION: This study suggests that although Tc-99m DMSA scintigraphy remains the gold standard method for evaluating parenchymal abnormalities, Tc-99m EC scintigraphy can be a reliable single-modality study to evaluate renal cortical defects, DRF, perfusion, drainage of the urinary system, and indirect evidence of vesicoureteric reflux with the added advantage of low radiation exposure to the patient.

Unfused renal ectopia: a rare form of congenital renal anomaly.

Unfused crossed renal ectopia observed 1 in 75,000 autopsies is a rare congenital anomaly. Typically one kidney is located in the proximity of the other kidney, and the ureter of the anatomically anomalous kidney crosses the midline to insert to the bladder in its normal anatomic position. Although renal function is usually not affected, the condition is generally accompanied by other congenital anomalies. In this case report, static and dynamic scintigraphic images of two patients with unfused crossed renal ectopia are presented. Besides properties of imaging modalities, clinical features are discussed in light of the available literature.

Effectiveness of diuretic injection on the measurement of differential renal function using Tc-99m DMSA in patients with a dilated renal pelvis.

AIM: The aim of this study was to evaluate the effectiveness of diuretic injection for the measurement of differential renal function (DRF) with technetium-99m dimercaptosuccinic acid (Tc-99m DMSA) scintigraphy in patients with a dilated pelvis. MATERIALS AND METHODS: A total of 46 patients who were referred for both technetium-99m-L,L-ethylenedicysteine (Tc-99m L,L-EC) and Tc-99m DMSA imaging and found to have a dilated collecting system on Tc-99m EC scintigraphy were studied. Four to 5 hours after intravenous injection of Tc-99m DMSA, imaging was performed in the supine position, and posterior, anterior, left and right lateral, and left and right posterior oblique views were taken. After this study, furosemide was administered intravenously and 30 minutes later, additional images in the anterior and posterior views were obtained. RESULTS: The kidneys were evaluated into 2 groups. Group 1 comprised 12 kidneys that had an obstructive curve pattern on Tc-99m EC scans. Group 2 comprised 34 kidneys that had a nonobstructive dilated renogram curve pattern. DRF of the kidneys in each patient were calculated, and the values obtained from the standard and diuretic DMSA scans were compared with each other for all patients and each group. Considering all the patients, the values of mean DRF on both standard and diuretic DMSA images were 55.4%+/-21.2% and 55.4%+/-21.5%, respectively. There were no significant differences between DRF values of each kidney obtained by the 2 methods. When we compared the DRF values in groups 1 and 2, there were again no significant differences. In group 1, the values of mean DRF on standard and diuretic images were 51.7%+/-13.7% and 51.6%+/-13.9%, respectively, and in group 2, the values of mean DRF were 56.7%+/-23.4% and 56.7%+/-23.6%, respectively. CONCLUSION: In view of our study, diuretic administration seems to be an unnecessary intervention because it has no effect on the accuracy of DRF measurements using DMSA scintigraphy in patients with a dilated collecting system whether it is obstructed or not.

Thyroid hemiagenesis: a report of three cases and review of the literature.

Thyroid hemiagenesis resulting from the failure of embryologic development of one thyroidal lobe is a very rare anomaly. It is usually incidentally discovered during the investigation of accompanying thyroid disorders. Here we report three cases with right lobe agenesis in two patients and left lobe agenesis in one patient. Two of them were hyperthyroid, while the other euthyroid patient had a thyroid mass.

Washout rates of Tc-99m tetrofosmin in asymmetric septal hypertrophy.

The aim of this study was to evaluate the washout rate of Tc-99m tetrofosmin in asymmetric septal hypertrophy (ASH). As Tc-99m tetrofosmin accumulation and retention depend on sarcolemmal and/or mitochondrial function, the presence or absence of abnormalities in the washout rate of Tc-99m tetrofosmin could provide information about sarcolemmal and/or mitochondrial damage noninvasively. The study group consisted of 18 patients with ASH and 10 healthy subjects. After intravenous injection of 1110 MBq (30 mCi) Tc-99m tetrofosmin, tomographic images were obtained 1 hour later (early image) and again 4 hours later (delayed image). Using tomographic images, the distribution and washout of tetrofosmin in the left ventricle was examined quantitatively. Short-axis SPECT images were divided into 5 segments (anterior, septal, lateral, inferior wall and apex) in early and delayed images, and the mean radioactivity counts were measured in each segment by drawing regions of interest. Washout rates of apex, anterior, septal, lateral and inferior walls were 0.34 +/- 0.06, 0.37 +/- 0.07, 0.36 +/- 0.07, 0.33 -/+ 0.08, 0.33 +/- 0.07 in ASH and 0.20 +/- 0.05, 0.23 +/- 0.05, 0.22 +/- 0.03, 0.21 +/- 0.03, 0.22 +/- 0.03 in the normal group, respectively. In ASH, the washout rates of all myocardial segments were significantly increased as compared to those of the normal controls (p < 0.05). The findings of the present study suggest that there could be dysfunction of sarcolemma and/or mitochondria in the entire left ventricle which would be important in the pathophysiology of this disease. Also our study revealed that Tc-99m tetrofosmin washout was higher in NYHA II-III patients compared to NYHA I patients and the degree of Tc-99m tetrofosmin washout corresponded well with the thickness of the interventricular septum and posterior walls.