Sameer Taywade

PSMA Expression in Papillary Thyroid Carcinoma: Opening a New Horizon in Management of Thyroid Cancer?

Prostate-specific membrane antigen (PSMA) is a type 2 transmembrane protein highly expressed in prostate cancer cells. We present the case of a 50-year-old man with metastatic papillary carcinoma of the thyroid, with rising thyroglobulin level and negative whole-body radioiodine scan after total thyroidectomy. Considering the limited treatment options available, it was decided to perform Ga-PSMA-HBED-CC PET/CT scan. It revealed intense radiotracer uptake in mediastinal and left supraclavicular lymph nodes, brain metastases, bilateral lung nodules, and skeletal sites. Patient also underwent F-FDG PET/CT. It demonstrated similar findings; however, the number of lesions detected in brain was less compared with Ga-PSMA PET/CT.

Comparison of 18F-Fluorocholine positron emission tomography/computed tomography and four-dimensional computed tomography in the preoperative localization of parathyroid adenomas-initial results

Objective: We aimed to compare the diagnostic accuracy of 18F-Fluorocholine (FCH)-positron emission tomography/computed tomography (PET/CT) and four-dimensional (4D)- CT in detection and localization of eutopic and ectopic parathyroid adenoma (PA) in patients with hyperparathyroidism. Materials and Methods: Five patients with primary hyperparathyroidism underwent FCH-PET/CT after 60 min of 185 MBq of intravenous 18F-FCH administration. Images were acquired from head to mediastinum at 3 min per bed position. No intravenous contrast was used. All patients underwent 4D-CT within 2 weeks of the FCH-PET/CT, with a precontrast, post contrast arterial, and venous phase with 75 ml intravenous Iohexol 350 followed by 25 ml saline chase. Histopathology was considered as the gold standard. Results: Both modalities showed 100% concordance in the detection of parathyroid lesions. Both FCH-PET/CT and 4D-CT detected 7 lesions in 5 patients, with 4 patients having a single lesion, and 1 patient having three lesions. Of the 7 reported lesions, 4 were eutopic and 3 were ectopic. No additional lesions were detected by either modality in comparison to the other. All 7 specimens were resected and histopathology showed PA/hyperplasia. Conclusion: FCH-PET/CT and 4D-CT are equally efficacious in detection and localization of eutopic and ectopic PA. This may open up the possibility of using FCH-PET/CT in patients with negative conventional imaging who cannot undergo contrast studies.

Role of (18)F-FDG PET-CT in Monitoring the Cyclophosphamide Induced Pulmonary Toxicity in Patients with Breast Cancer - 2 Case Reports.

Drug induced pulmonary toxicity is not uncommon with the use of various chemotherapeutic agents. Cyclophosphamide is a widely used chemotherapeutic drug in the treatment of breast cancer. Although rare, lung toxicity has been reported with cyclophosphamide use. Detection of bleomycin induced pulmonary toxicity and pattern of 18F-fluorodeoxyglucose (18F-FDG) uptake in lungs on fluorodeoxyglucose positron emission tomography-computed tomography (18F-FDG PET-CT) has been elicited in literature in relation to lymphoma. However, limited data is available regarding the role of 18F-FDG PET-CT in monitoring drug induced pulmonary toxicity in breast cancer. We here present two cases of cyclophosphamide induced drug toxicity. Interim 18F-FDG PET-CT demonstrated diffusely increased tracer uptake in bilateral lung fields in both these patients. Subsequently there was resolution of lung uptake on 18F-FDG PET-CT scan post completion of chemotherapy. These patients did not develop significant respiratory symptoms during chemotherapy treatment and in follow up.

Does the intensity of diffuse thyroid gland uptake on F-18 fluorodeoxyglucose positron emission tomography/computed tomography scan predict the severity of hypothyroidism? Correlation between maximal standardized uptake value and serum thyroid stimulating hormone levels.

Context: F-18 fluorodeoxyglucose (F-18 FDG) positron emission tomography/computed tomography (PET/CT) scan and hypothyroidism. Aims: The aim was to determine whether the intensity of diffuse thyroid gland uptake on F-18 FDG PET/CT scans predicts the severity of hypothyroidism. Materials and Methods: A retrospective analysis of 3868 patients who underwent F-18 FDG PET/CT scans, between October 2012 and June 2013 in our institution for various oncological indications was done. Out of them, 106 (2.7%) patients (79 females, 27 males) presented with bilateral diffuse thyroid gland uptake as an incidental finding. These patients were investigated retrospectively and various parameters such as age, sex, primary cancer site, maximal standardized uptake value (SUVmax), results of thyroid function tests (TFTs) and fine-needle aspiration cytology results were noted. The SUVmax values were correlated with serum thyroid stimulating hormone (S. TSH) levels using Pearsons correlation analysis. Statistical Analysis Used: Pearsons correlation analysis. Results: Clinical information and TFT (serum FT3, FT4 and TSH levels) results were available for 31 of the 106 patients (27 females, 4 males; mean age 51.5 years). Twenty-six out of 31 patients (84%) were having abnormal TFTs with abnormal TSH levels in 24/31 patients (mean S. TSH: 22.35 μIU/ml, median: 7.37 μIU/ml, range: 0.074-211 μIU/ml). Among 7 patients with normal TSH levels, 2 patients demonstrated low FT3 and FT4 levels. No significant correlation was found between maximum standardized uptake value and TSH levels (r = 0.115, P > 0.05). Conclusions: Incidentally detected diffuse thyroid gland uptake on F-18 FDG PET/CT scan was usually associated with hypothyroidism probably caused by autoimmune thyroiditis. Patients should be investigated promptly irrespective of the intensity of FDG uptake with TFTs to initiate replacement therapy and a USG examination to look for any suspicious nodules.

Prevalence of ECG changes during adenosine stress and its association with perfusion defect on myocardial perfusion scintigraphy

Objective Myocardial perfusion scintigraphy (MPS) is a valuable, noninvasive imaging modality in the evaluation of patients with coronary artery disease. Adenosine stress may occasionally be associated with ECG changes. This study evaluated the strength of association between adenosine stress-related ECG changes and perfusion defects on 99mTc-MPS. Patients and methods 117 (mean age: 61.25±9.27 years; sex: men 87, women 30) patients with known/suspected coronary artery disease underwent adenosine stress MPS. ECG was monitored continuously during adenosine stress for ST-depression. On the basis of the summed difference score, reversible perfusion defects were categorized as follows: normal: less than 4, mild: 4–8, moderate: 9–13, and severe: more than 13. Results ST-depression was observed in 27/117 (23.1%) and reversible perfusion defects were observed in 18/27 (66.66%) patients. 2/27, 6/27, and 10/27 patients had mild, moderate, and severe ischemia, respectively. 9/27 patients had normal perfusion. ECG changes and perfusion defects showed a moderate strength of association (correlation coefficient r=0.35, P=0.006). The sensitivity, specificity, positive predictive value, and negative predictive value of ECG findings for prediction of ischemia were 35.29, 86.36, 67.67, and 63.33%, respectively. Conclusion ECG changes during adenosine stress are not uncommon. It shows a moderate strength of association with reversible perfusion defects. ECG changes during adenosine merit critical evaluation of MPS findings.

Identification of optimal mask size parameter for noise filtering in 99mTc-methylene diphosphonate bone scintigraphy images

99mTc-methylene diphosphonate (99mTc-MDP) bone scintigraphy images have limited number of counts per pixel. A noise filtering method based on local statistics of the image produces better results than a linear filter. However, the mask size has a significant effect on image quality. In this study, we have identified the optimal mask size that yields a good smooth bone scan image. Forty four bone scan images were processed using mask sizes 3, 5, 7, 9, 11, 13, and 15 pixels. The input and processed images were reviewed in two steps. In the first step, the images were inspected and the mask sizes that produced images with significant loss of clinical details in comparison with the input image were excluded. In the second step, the image quality of the 40 sets of images (each set had input image, and its corresponding three processed images with 3, 5, and 7-pixel masks) was assessed by two nuclear medicine physicians. They selected one good smooth image from each set of images. The image quality was also assessed quantitatively with a line profile. Fisher’s exact test was used to find statistically significant differences in image quality processed with 5 and 7-pixel mask at a 5% cut-off. A statistically significant difference was found between the image quality processed with 5 and 7-pixel mask at P=0.00528. The identified optimal mask size to produce a good smooth image was found to be 7 pixels. The best mask size for the John-Sen Lee filter was found to be 7×7 pixels, which yielded 99mTc-methylene diphosphonate bone scan images with the highest acceptable smoothness.

Unusual presentation of rare cardiac tumor: The role of F-18-fluorodeoxyglucose positron emission tomography/computed tomography

Primary cardiac tumors are rare with angiosarcoma being the most common among malignant cardiac tumor. We present a case of 30-year-old female patient in whom F-18-fluorodeoxyglucose positron emission tomography/computed tomography demonstrated a necrotic mass in right atrium with multiple fluorodeoxyglucose avid lesions in both upper and lower alveolus, liver, multiple bones, and bilateral lungs. Patient underwent biopsy from gum swelling which revealed metastatic angiosarcoma.

Tc-99m TRODAT uptake in an osteoid tumor of clivus

Tc-99m TRODAT is cocaine analog and binds to the dopamine transporter in vivo. Tc-99m TRODAT single-photon emission computed tomography/computed tomography. (SPECT/CT) is useful for demonstrating presynaptic dopaminergic dysfunction in patients with Parkinsonism. However, few reports have shown extrastriatal uptake of Tc-99m TRODAT. We present the case of a 67-year-old male who underwent Tc-99m TRODAT SPECT/CT for evaluation of Parkinsonism. In addition to tracer binding in the striatum, tracer uptake was noted in an osteoid tumor of the clivus. Integrated SPECT/CT enabled precise localization and characterization of the extrastriatal site of tracer binding and emphasizes the importance of such coincidental findings.