Three cases with unusual false positive radioiodine uptake in three different organs and pathologies (infective old fibrotic lesion in the lung, simple liver cyst, and benign breast lesion) on iodine-131 (131I) whole body scintigraphy. Clinicoradiological correlation was undertaken in all three cases and the pathologies were ascertained. In all the three cases, single-photon emission computerized tomography-computed tomography (SPECT-CT) and ancillary imaging modalities were employed and were helpful in arriving at the final diagnosis.

Background: Osteoid osteoma is a benign bone tumor; diagnosed using x-ray and Computer Tomography (CT). It shows a nidus and cortical thickening. When the nidus is not well visualised especially in uncommon locations; Bone Scan (BS) can be performed for evaluation of osteoid osteoma.Methods: A retrospective observational study was done where 21 subjects presenting with suspicion of osteoid osteoma underwent BS using 10-20mCi (370 to 740MBq) of Technetium-99m Pertechnetate with perfusion, delayed cortical and Single Photon Emission Tomography/Computer Tomography (SPECT/CT). Increased perfusion and delayed focal cortical uptake was assessed on BS to locate osteoid osteoma. Response evaluation to Radiofrequency ablation (RFA) was also performed using BS.Results: Osteoid osteoma was detected in femur (8), spine (3), forearm bones (2), humerus (2), tibia (2), fibula in one and iliac bone in one patient using BS. BS detected more lesions (18) than CT scan where nidus as confirmatory sign was seen in 13 lesions. The McNemar test showed no significant difference (p=0.22) in the detection of osteoid osteoma using CT and BS in common location of femur. However there was significant difference noted between BS and CT in uncommon site (p=0.023). 3/8 patients showed persistent increased cortical activity after RFA ablation on BS.Conclusions: BS was more useful for confirmation of diagnosis of Osteoid osteoma for lesions in uncommon sites. BS also helped to assess response to RFA ablation therapy. SPECT/CT improved interpretation of BS to locate the osteoid osteoma.

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Imaging of dextrocardia in humans requires an understanding of the orientation of the heart chambers and walls. There are many types of cardiac malpositioning, such as dextrocardia (with or without situs inversus), mesocardia, and levocardia. Myocardial perfusion scintigraphy of dextrocardia has been explained in case reports and imaging atlases; however, myocardial viability assessment using nuclear medicine imaging techniques is less documented in the literature. Methods: In 2 cases of dextrocardia with situs inversus and 1 case of mesocardia, myocardial viability was assessed using 99m Tc-sestamibi rest perfusion scintigraphy and 18 F-FDG PET. Cardiac SPECT images of dextrocardia with situs inversus were acquired using the feet-first supine position with a 180°arc from left anterior oblique to right posterior oblique, whereas a rightlateral-to-left-lateral arc was used for mesocardia. The processing and reconstruction were done by entering the dataset for the feetfirst supine position and repeating after entering the dataset for the feet-first prone position. The 2 sets of reconstructed images were compared for orientation of walls and cardiac chambers. Results: The first processing, using the feet-first supine position, revealed an interchanged septum and lateral wall in reconstructed images of dextrocardia with situs inversus. This interchange was corrected by changing the position to prone during processing of the rest perfusion and PET raw data. The display of cardiac slices in various axes matched the conventional nomenclature for the septum and lateral wall, leading to easy interpretation. However, this change was not required in the mesocardia, for which the location of the heart chambers was not interchanged. Conclusion: Because the acquisition protocol for SPECT is a semicircular orbit, the various types of dextrocardia require careful selection of the arc, with the patient positioning kept feet-first supine. Processing and reconstruction of data by changing the patient position to prone was found to be most useful method of matching the septum and lateral wall orientation for interpretation of images.

Objective Localization of epileptogenic focus in drug-refractory epilepsy using Tc-99m ethylene cystine dimer (ECD) brain single photon emission computed tomography (SPECT) is less studied in patients with discordant findings on video electroencephalogram (VEEG) and MRI. The study was done to evaluate brain SPECT for epileptogenic focus localization and postoperative seizure freedom. Methods Epilepsy patients with discordant VEEG and MRI findings underwent brain SPECT at ictal and interictal phases. Various groups unilateral/bilateral mesial temporal sclerosis (MTS), solitary and multifocal lesional, nonlesional epilepsy were studied for localization of epileptogenic focus and postoperative seizure freedom (>2 years) using Engels classification. Reasons for nonoperability was evaluated in nonoperated group. Results SPECT could localize epileptogenic focus in 49/67 (73.13%) and guided surgery in 19/33 (57.57%) patients in operated group. SPECT was useful in 12 (46.12%) of unilateral (2)/bilateral (10) MTS. Postoperative seizure freedom of Engels Class I and II in 22 (66.67%), III in six (18.2%) and IV in one patient based on SPECT findings (P = 0.0086). Overall sensitivity and specificity were 79.3% and 85.7%, respectively. SPECT could localize epileptogenic focus in 23/34 (67.64%) patients in nonoperated group; 10 (29.41%) patients refused for surgery and no epileptogenic focus was localized in the rest of 14 (41.2%). Conclusion Ictal SPECT showed incremental value and was found necessary for epileptogenic focus localization and subsequent surgery in unilateral/bilateral MTS in this study. Seizure freedom in patients undergoing epilepsy surgery based on ictal SPECT assistance was comparable to the surgical group not requiring ictal SPECT.