Abhishek Behera

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.

Development and validation of the suprathreshold stochastic resonance-based image processing method for the detection of abdomino-pelvic tumor on PET/CT scans

Purpose: The detection of abdomino-pelvic tumors embedded in or nearby radioactive urine containing 18F-FDG activity is a challenging task on PET/CT scan. In this study, we propose and validate the suprathreshold stochastic resonance-based image processing method for the detection of these tumors. Methods: The method consists of the addition of noise to the input image, and then thresholding it that creates one frame of intermediate image. One hundred such frames were generated and averaged to get the final image. The method was implemented using MATLAB R2013b on a personal computer. Noisy image was generated using random Poisson variates corresponding to each pixel of the input image. In order to verify the method, 30 sets of pre-diuretic and its corresponding post-diuretic PET/CT scan images (25 tumor images and 5 control images with no tumor) were included. For each sets of pre-diuretic image (input image), 26 images (at threshold values equal to mean counts multiplied by a constant factor ranging from 1.0 to 2.6 with increment step of 0.1) were created and visually inspected, and the image that most closely matched with the gold standard (corresponding post-diuretic image) was selected as the final output image. These images were further evaluated by two nuclear medicine physicians. Results: In 22 out of 25 images, tumor was successfully detected. In five control images, no false positives were reported. Thus, the empirical probability of detection of abdomino-pelvic tumors evaluates to 0.88. Conclusion: The proposed method was able to detect abdomino-pelvic tumors on pre-diuretic PET/CT scan with a high probability of success and no false positives.

Metastatic superscan on 99m Tc-methylene diphosphonate bone scintigraphy in pediatric neuroblastoma

Excessive skeletal radioisotope uptake in relation to soft tissues along with absent or faint activity in the genitourinary tract on bone scintigraphy (BS) is known as a “superscan.” However the association of pediatric solid tumor malignancy with metastatic superscan has not been reported previously. We here describe two such cases of neuroblastoma who presented with metastatic superscan on 99mTc-methylene diphosphonate BS. Presence of a superscan usually indicates an advanced stage of the disease. The patient prognosis is usually poor. Though extremely rare superscan can be associated with pediatric solid tumor malignancies and should be kept in mind while reporting such cases.

Radiation-Induced Esophagitis Masquerading as Disease Progression in Case of Esophageal Carcinoma: A Diagnostic Dilemma Solved on Follow-up FDG PET/CT.

Radiation esophagitis is one of the commonest complications of the radiotherapy involving esophagus. It is characterized by diffuse radiotracer uptake in the esophagus on ¹⁸F-FDG PET/CT. Thus, it can be often confused with the esophageal malignancy. We present the sequential ¹⁸F-FDG PET/CT images of a 45-year-old woman with locally advanced squamous cell carcinoma of the esophagus who developed radiation esophagitis after chemoradiotherapy. It was confused with the progression of the disease, and the dilemma was resolved by the follow-up PET/CT.