Gonca Kara Gedik

The role of fluorodeoxyglucose-positron emission tomography/computed tomography in differentiating between benign and malignant adrenal lesions.

ObjectivesThis retrospective study was designed to investigate the clinical role of whole-body positron emission tomography/computed tomography (PET/CT) by using 2-[18F]fluoro-2-deoxy-D-glucose (FDG), for the evaluation of adrenal lesions and to find the best index to distinguish benign from malignant lesions in various cancer patients. Materials and methodsA total of 81 patients (55 male and 26 female, age range: 31–81 years, mean: 61.5) who had confirmed primary malignancies (lung cancer in 47 patients, gastrointestinal malignancies in 13 patients, malignant melanoma in one patient, renal cell cancer in three patients, mesothelioma in two patients, breast carcinoma in nine patients, cervical cancer in one patient, ovarian cancer in two patients, pheochromocytoma in one patient, unknown primary in two patients) underwent PET/CT examinations for cancer screening, staging, restaging, and detection of suspected recurrence. Of the 81 patients, 104 adrenal lesions (34 benign and 70 malignant adrenal lesions) were shown by CT. On visual analysis of PET/CT imaging, adrenal uptake was based on a three-scale grading system. For final assessment standards of references for adrenal malignant lesions was based on biopsy (n=2), interval growth, or reduction after chemotherapy. An adrenal lesion, which remained unchanged on clinical and imaging follow-up of at least 7 months (mean follow-up time 19.31 months±6.46, range 7–30 months), was decided as a benign lesion. ResultsIn adrenal malignant lesions maximum standardized uptake value (SUVmax) (8.82±4.47) was higher than that of adrenal benign lesions (3.02±1.15, P<0.0001). In the differentiation of adrenal benign and malignant lesions, a CT threshold of 10 Hounsfield units corresponded to a sensitivity of 64.7%, specificity of 98.6%, and accuracy of 87.5%. An SUVmax cut-off value of 2.5 corresponded to a sensitivity of 100%, specificity of 38.2%, and accuracy of 80%. An SUVmax cut-off value of 4.2 corresponded to a sensitivity of 88.6%, specificity of 88.2%, and accuracy of 88.5%. The ratio of tumor SUVmax to liver SUVmean was 3.61±1.77 for adrenal malignant lesions whereas it was 1.20±0.38 for adrenal benign lesions (P<0.0001). T/L SUV ratio cut-off value of 1.8 corresponded to a sensitivity of 87%, specificity of 91%, and accuracy of 88.5%. T/L SUV ratio cut-off value of 1.68 corresponded to a sensitivity of 90%, specificity of 91.1%, and accuracy of 90.4%. Conclusion2-[18F]fluoro-2-deoxy-D-glucose-PET/CT improves the diagnostic accuracy in the differentiation of benign from malignant adrenal lesions in various cancer patients. Combined information obtained from PET/CT (SUVmax, T/L SUV ratio, visual analysis) and unenhanced CT (size, Hounsfield units measurement) is recommended for better differentiation.

Unusual extracardiac findings detected on myocardial perfusion single photon emission computed tomography studies with Tc-99m sestamibi.

The authors describe the incidence and various uptake patterns of Tc-99m sestamibi (MIBI) in the extracardiac area due to unusual causes on myocardial perfusion single photon emission computed tomography (SPECT) studies. Seven patients are presented in whom incidental extracardiac findings were observed during the interpretation of the raw data besides the routine evaluation of myocardial reconstructed SPECT slices. These 7 patients were detected out of 582 consecutive patients (1.2%) who had myocardial perfusion SPECT with Tc-99m MIBI. The findings on the raw data led to additional reconstruction of thoracic SPECT images and eventually detailed examination of the extracardiac area. Two of the patients underwent surgery because of incidental extracardiac findings (thymoma and multinodular goiter) on cardiac scintigraphy. Other causes of increased extracardiac activity were the intestine protruded through the left hemithorax, uptake in the pulmonary arterial wall, and pulmonary interstitial fibrosis due to sarcoidosis. The reasons for decreased Tc-99m MIBI accumulation in the extracardiac area in the 2 other patients were significantly dilated pulmonary arteries and hydatic cyst, which were not defined before to our knowledge. Familiarity with the normal biodistribution and variable uptake patterns in the raw images becomes necessary during the interpretation of myocardial SPECT in order not to miss very unusual incidental extracardiac uptake or information that could lead to alteration in patient management. Potential underlying mechanisms of extracardiac Tc-99m MIBI accumulation are discussed, and the literature about noncardiac Tc-99m MIBI findings detected on myocardial perfusion SPECT studies was reviewed.

Comparison of extraarticular leakage values of radiopharmaceuticals used for radionuclide synovectomy

ObjectivesRadionuclide synovectomy is a reliable therapy in patients with chronic synovitis. However, radiation doses delivered to non-target organ systems due to leakage of radioactive material from the articular cavity are an important disadvantage of this procedure. In this study we compared extraarticular leakage values of the 3 commonly used radiopharmaceuticals;90Y-citrate,90Y-silicate and186Re-sulfide colloid.Materials and MethodsThirty-five patients with persistent synovitis were enrolled in the study. Twenty-two hemophilic, 8 rheumatoid arthritis and 5 patients with pigmented villonodular synovitis were studied.90Y labeled silicate and citrate were used for knee joints and186Re-sulfide for intermediate sized joints. Radiocolloid leakage values were evaluated using a gamma camera with 20% window centered over the bremsstrahlung photopeak of90Y and a respective window over the 137 keV photopeak of186Re. Regions of interest were drawn over the injection site, the regional lymph nodes and the background areas. Leakage of radiocolloid was calculated by dividing the counts/pixel in the regional lymph node area to the counts/pixel in the injection site.ResultsNo visible leakage was observed. The median leakage values calculated for90Y-citrate,90Y-silicate and186Re-sulfide were found as 1.9%, 2.4% and 2.7%, respectively. The difference between the variability of leakage values was not statistically significant (p > 0.05).Conclusion: There was no significant difference in terms of extraarticular leakage between90Y-citrate,90Y-silicate and186Re-sulfide radiocolloids.

Is corticosteroid coinjection necessary for radiosynoviorthesis of patients with hemophilia

Purpose: Radiation synovectomy is frequently combined with intraarticular corticosteroid injection in the treatment of rheumatoid arthritis to reduce local inflammation and lymphatic clearance of radiocolloid. However, this practice is not universally accepted because corticosteroids have local and systemic toxicity such as osteonecrosis and cartilage damage and whether simultaneous corticosteroid injection together with radiocolloids is necessary in other forms of chronic synovitis like patients with hemophilia remains to be determined. Materials and Methods: In this study, we performed radiosynoviorthesis in 14 joints of 12 patients with hemophilia with chronic knee synovitis without corticosteroid coadministration and measured radiocolloid leakage from the joint space. Five mCi Y-90 radiocolloid was injected under local anesthesia and the needle was flushed with additional lidocaine injection instead of corticosteroid. The joint was then manipulated through a full range of extension and flexion to distribute the particles homogeneously throughout the joint space. The joint was then splinted for 48 hours to minimize leakage from the joint space. After the immobilization period, radiocolloid leakage was evaluated using a gamma camera with a 20% window centered over the maximum Bremsstrahlung photopeak of Y-90. Regions of interest were drawn to the injection site on the knee joint and to the ipsilateral inguinal lymph node area. Leakage of radiocolloid was calculated by dividing the background-corrected counts/pixel at the inguinal region by the counts/pixel at the injection site. Results: One of 12 patients who had knee arthroplasty was previously found to have a high amount of leakage. In this patient, 70% of radiocolloid at the injection site drained into the pelvic lymph nodes. In the remaining 11 patients, no lymph nodes were visualized in the groin area and the measured average leakage for these patients was 2.3% (range, 0–13). Conclusion: We concluded that in cases of appropriate particle size and strict immobilization of knee joints, leakage of radiocolloid was minimal and steroid coinjection might not be necessary for radiosynoviorthesis of patients with hemophilia with chronic knee synovitis.

Differential renal function estimation by dynamic renal scintigraphy: influence of background definition and radiopharmaceutical.

ObjectivesDifferential renal function (DRF) calculation with Tc-diethylenetriamine-pentaacetic acid (DTPA) or mercaptoacetyltriglycine (MAG3) is gaining clinical importance in the evaluation of patients with ureteropelvic junction obstruction with hydronephrosis (HN). Although many decisions regarding surgery are based on the functional changes detected by serial diuretic renography, the reliability of DRF estimation has been questioned. Factors such as the correction of nonrenal activity included in the renal region of interest (background subtraction) and immature function resulting in poor renal extraction may cause unusual elevation in the differential function. The aim of this study is to evaluate the impact of the radiopharmaceutical and positioning of the background on the DRF. Patients and methodsA prospective study was undertaken in 83 patients (48 male, 35 female, median age 5 years) with unilateral or bilateral ureteropelvic junction obstruction with or without HN. Forty-five and 38 renograms were performed with 99mTc-DTPA and 99mTc-MAG3, respectively. DRF was calculated using two different regions of interest (subrenal and perirenal) for background subtraction. Of the 83 patients, 37 also had dimercaptosuccinic acid scans. The difference between DRF based on background selection, age, radiopharmaceutical, and correlation with dimercaptosuccinic acid uptake was analyzed. The difference in DRF between two background (BG) drawings (sebrenal and perirenal) and 95% confidence intervals were calculated. ResultsFor 83 renograms, the mean difference was 4.82 (range −7 to +25, SD 5.26). The 95% confidence intervals were −3.67 to 5.97. Analysis of the data revealed that greater spread of DRF between the techniques was seen in patients with right HN (mean 7.96, P<0.001). In patients with right HN, when lower pole background activity was used, the right renal function was overestimated by an average of 4.67%. When MAG3 was used, all patients had statistically significant DRF for the different BG subtraction techniques, whereas the DRF values were only statistically different in those with right HN when DTPA was used. DiscussionThe current study supports the existence of BG-related variation in the DRF calculations. We found that the average counts in the perirenal BG more precisely represent nonrenal activity and recommend the use of semilunar-perirenal background region of interest to reduce the overlapping hepatic activity.

Askin's Tumor in an Adult: Case Report and Findings on 18F-FDG PET/CT

Primitive neuroectodermal tumor (PNET) of the chest wall or Askins tumor is a rare neoplasm of chest wall. It most often affects children and adolescents and is a very rare tumor in adults. In this case report, we present an Askins tumor occurred in a 73-year-old male. The patient was admitted with a history of 3-month lower back pain and cough. In computed tomography, there was a lesion with dimensions of 70 × 40 × 65 mm in the superior segment of the lower lobe of the left lung. Positron emission tomography/computed tomography with 18F-flourodeoxyglucose revealed a pleural-based tumor in the left lung with a maximum standardized uptake value of 4.36. No distant or lymph node metastases were present. The patient had gone through surgery, and wedge resection of the superior segment of left lobe and partial resection of the ipsilateral ribs were performed. Pathology report with immunocytochemistry was consistent with PNET and the patient received chemotherapy after that.

Relation between radionuclide imaging and pathologic findings of ureteropelvic junction obstruction in neonatal hydronephrosis

Objective. An excessive amount of collagen fibers around the muscle cells in the ureteropelvic junction could be responsible for obstruction in patients with hydronephrosis. We aimed to elucidate the ultrastructure of the ureters and correlate this finding with the prognostic outcome and to correlate the histopathological findings with diuretic radionuclide renography findings. Material and methods. Biopsy specimens of 20 children who underwent dismembered pyeloplasty for ureteropelvic junction obstruction were analyzed. The patients were grouped according to their age: infants (<12 months) and others (>12 months). Diuretic radionuclide imaging was performed using 99mTc mercaptylacetyltriglycine in the pre- and postoperative periods. Changes in differential renal function and excretion patterns on diuretic renography were evaluated in relation to the findings noted on histopathological examination of the biopsy specimens. Excretion patterns were classified as follows: A, normal; B, responsive to diuretic; C, minimal response to diuretic with some excretion after postural change; and D, very poor/no drainage despite diuretics. Biopsy materials were analyzed for the presence and extent of inflammation, fibrosis and changes in the smooth muscle layer using Massons trichrome stain and immunohistochemical staining. Histopathological findings were graded from zero to three, depending on severity. Results. In patients aged <12 months, preoperative differential renal function (DRF) was associated with fibrosis (F) and smooth muscle hypertrophy (SMH) [mean (SD) DRF for both F and SMH were Grade 0–1, 47.8% (6.4%); Grade 2–3, 36.2% (11.3%); p<0.05]; and change in DRF was associated with inflammation [Grade 0–1, −0.1% (4.0%); Grade 2–3, 5.8% (3.0%); p<0.05]. Excretion patterns or improvement in excretion were not associated with any of the histopathological features. Change in DRF was significantly associated with inflammation Grade 2–3 (beta coefficient, 5.8; 95% CI 1.4–10.3). Conclusions. Histopathological evaluation of renal parenchymal biopsy specimens obtained during pyeloplasty may be useful to provide an objective method for predicting the recovery of renal function. In addition, this will allow comparison of the types of histopathological alterations with the changes in differential renal function in order to predict the potential final improvement.

Differential diagnosis between secondary and tertiary hyperparathyroidism in a case of a giant-cell and brown tumor containing mass. Findings by 99m Tc-MDP, 18 F-FDG PET/CT and 99m Tc-MIBI scans

Brown tumor is one of the skeletal manifestations of hyperparathyroidism. It is a benign but locally aggressive bone lesion and its differential diagnosis with giant cell containing skeletal tumors or metastases may be complicated. We present a male patient with chronic renal failure who was initially misdiagnosed as having a giant-cell rich neoplasm of bone in his right thumb. Diffusely increased fluorine-18 fluorodeoxyglucose ((18)F-FDG) uptake in the axial and appendicular skeleton and multiple (18)F-FDG avid lytic lesions suggesting multiple metastases were observed on the (18)F-FDG positron emission tomography/computed tomography (PET/CT) scan. On the usual technetium-99m methylene diphosphonate ((99m)Tc-MDP) bone scan we noticed diffusely increased uptake in the skeleton and two focuses with very much increased uptake, which suggested a metabolic bone disease rather than a multiple metastatic giant cell tumor or bone metastases. Additional investigation documentated increased levels of parathyroid hormone. Parathyroid hyperplasia was finally diagnosed with (99m)Tc-methoxyisobutylisonitrile (MIBI) parathyroid scintigraphy. Fluorine-18-FDG avid lytic lesions were attributed to hyerparathyroidism associated brown tumors instead of multiple metastases. In conclusion, we present a patient with chronic renal insufficiency, who suffered from secondary and later from tertiary HPT with polyostotic brown tumors, which were best shown by the (18)F-FDG PET/CT than by the (99m)Tc-MDP or the (99m)Tc-MIBI scans.

Radiosynovectomy: current status in the management of arthritic conditions.

Departments of Nuclear Medicine, Orthopedics and Traumatology, Faculty of Medicine, Hacettepe University, Ankara, Turkey and Department of Medicine Service-PET Unit, ‘S. Maria della Misericordia’ Hospital, Istituto Oncologico Veneto (IOV) – IRCCS, Rovigo, Italy Correspondence to Dr Ömer Uğur, Department of Nuclear Medicine, Faculty of Medicine, Hacettepe University, Ankara, Turkey Tel: + 90 312 305 1336; fax: + 90 312 309 3508; e-mail: ougur@hacettepe.edu.tr

Undescended Testis in Inguinal Canal Detected Incidentally on Fluorodeoxyglucose PET/CT Imaging

The differential diagnosis at the inguinal region is very important for hypermetabolic foci because of the possibility of metastasis at this level in cancer patients ongoing PET imaging for detection of metastases. It is important to distinguish this activity from other possible malignant and benign conditions such as lymph node activity, testicular cancer, metastatic disease activity, inflammation and urine skin contamination artefact. A 66-year-old male patient with operated colon cancer and liver metastasis was referred for PET/CT examination for re-staging because of suspicious metastases. Findings of PET/CT imaging with undescended testis detected incidentally was presented.