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Objective: The aim of this study was to assess the biodistribution and dosimetry of 177 Lu-DOTA-trastuzumab in patients with HER2-positive breast carcinoma using whole-body (WB) planar imaging at multiple time points., Patients and Methods: This study was a prospective evaluation of HER2-positive metastatic/locally advanced breast carcinoma patients who underwent gamma camera imaging for dosimetry and biodistribution studies by using 177 Lu-DOTA-trastuzumab. The standard diagnostic dosimetry protocol was followed, which included cold trastuzumab injection followed by in-house produced 177 Lu-DOTA-trastuzumab. Serial WB planar images (anterior and posterior) were obtained on gamma camera after the infusion of 177 Lu-DOTA-trastuzumab at multiple time points. Whole-body and organ regions of interest were drawn, and the numbers of disintegrations were obtained. The mean absorbed doses for the liver, spleen, kidneys, heart, red marrow, and tumor were obtained from OLINDA EXM v2.1.1 and ORIGIN software., Results: The study included a cohort of 21 female breast carcinoma patients. Tracer activity ( 177 Lu-DOTA-trastuzumab) was noted in the physiological organs such as the liver, spleen, kidneys, heart, as well as in the tumors. On visual analysis of 177 Lu-DOTA-trastuzumab biodistribution, the liver activity showed gradual clearance over time, and although spleen was comparatively faintly visualized than liver and similarly, kidneys were faintly visualized suggestive of the alternate route of tracer excretion. The maximum number of patients (n = 12) showed 2 components of clearance, namely, fast and slow. The average effective half-life of all the patients (including single and 2 components of clearance) was 106.25 ± 22.14 hours (84.11-128.39 hours). The mean absorbed dose for the liver, spleen, kidneys, heart, whole body, and red marrow was 1.0702 ± 0.731, 1.4114 ± 0.462, 1.4232 ± 0.364, 1.4719 ± 0.602, 0.2412 ± 0.0295, and 0.1485 ± 0.0213 mGy/MBq, respectively, by OLINDA EXM and 0.5741 ± 0.333, 0.8096 ± 0.224, 0.7943 ± 0.235, 1.8971 ± 0.713, and 0.09619 ± 0.0144 for liver, spleen, kidneys, heart and whole body respectively by ORIGIN. The absorbed radiation dose for tumor was 1.94E+2 by OLINDA EXM software and 1.78E+2 by ORIGIN software. In this study, during and after infusion of 177 Lu-DOTA-trastuzumab, no major adverse effects were noted in any patient except 1 patient who had grade 1 nausea and managed conservatively by antiemetic drug., Conclusions: The results of our study demonstrated expected and favorable biodistribution and dosimetry with 177 Lu-DOTA-trastuzumab in HER2-positive breast carcinoma patients. We noticed the mean absorbed dose to the normal organs within the limits of maximum tolerable dose, and also tumor dose was higher than the normal liver dose. Therefore, we conclude that 177 Lu-DOTA-trastuzumab radioimmunotherapy is feasible and a safe treatment option for treating HER2-positive breast carcinoma patients., Competing Interests: Conflicts of interest and sources of funding: none declared., (Copyright © 2024 Wolters Kluwer Health, Inc. All rights reserved.)

A case of 18F-FDG PET in pulmonary alveolar microlithiasis with bilateral reticulonodular opacities in the middle and lower zones on routine chest roentgenogram and calcification in the peribronchovascular interstitium,peribronchovascular and subpleural intralobular septal regions, and visceral pleura on high-resolution chest CT is presented. 18F-fluoride PET demonstrated intense tracer uptake in the lower zone of both lungs corresponding to CT findings. Minimal FDG activity in areas of dense calcification suggests minimal or no inflammation. This could account for the absence of symptoms in most cases despite remarkable imaging findings.

In the present communication, an unusual combination of scalp soft tissue and underlying brain involvement with intact skull bone coupled with bilateral renal involvement from a mediastinal diffuse large B cell lymphoma (DLBL) is presented. A 45-year-old man, a diagnosed case of mediastinal DLBL with bilateral lung involvement, was treated with conventional 6 cycles of chemotherapy and local external radiotherapy with initial good treatment response evidenced by considerable regression in mass size and regression in pulmonary lesions. Three months later, he returned with complaints of soft tissue swelling over the scalp; one of them in the high parietal bone and the other over the occipital region. A whole body FDG-PET at this time showed 2 moderate-sized foci in the scalp (with preservation of both tables of skull bone) and corresponding large foci in the brain parenchyma beneath, a superior mediastinal focus, a few foci in the apical and lower zone of left lung, extensive irregular uptake in the right pleura and the right lung parenchyma coupled with a loculated effusion in its lower zone and studded foci of hypermetabolism throughout the bilaterally enlarged kidneys. CT of the head confirmed the FDG-PET findings and histopathology of the biopsy from the scalp swelling was suggestive of DLBL. Ultrasound imaging of the abdomen showed lobulated bilaterally enlarged kidneys with multiple hypoechoic areas within them. The patient underwent palliative local external radiotherapy to the brain and systemic chemotherapy with poor clinical results with raised serum beta-2 microglobulin and serum LDH levels and deranged renal function. The patient died within a month after the FDG-PET study. The event of scalp and bilateral renal involvement from DLBL is rare in lymphoma literature and this report highlights that such unusual events can occur as part of widespread dissemination and underscores the importance of whole-body imaging with FDG-PET.