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Purpose: We aimed to investigate the response to balloon pulmonary angioplasty (BPA) in chronic thromboembolic pulmonary hypertension (CTEPH) using semi-quantitative analysis of lung perfusion SPECT/CT. Methods: This is a single-center retrospective study of patients with CTEPH who underwent BPA and pre- and post-BPA lung perfusion SPECT/CT between 2015 and 2022. Segmental defects on SPECT/CT were visually assessed and semi-quantitatively scored as 1 (large defect) or 0.5 (moderate defect) in accordance with modified PIOPED II criteria. The perfusion defect score was defined as (Σ segmental defect scores/18) × 100 (%). Associations between perfusion defect score and hemodynamic or functional parameters including WHO functional class, six-minute walking distance (6MWD), serum B-type natriuretic peptide (BNP), mean arterial pulmonary pressure (mPAP), pulmonary vascular resistance (PVR), and tricuspid regurgitation pressure gradient (TRPG) on echocardiography were statistically analyzed. Results: A total of 24 consecutive patients were included. The perfusion defect score significantly improved after BPA (median 58.3% vs. 47.2%, P < 0.001), in conjunction with the WHO functional class, 6MWD, serum BNP, mPAP, and TRPG. Perfusion defect scores were significantly correlated with 6MWD (rho = − 0.583, P < 0.001), serum BNP (rho = 0.514, P < 0.001), mPAP (rho = 0.583, P < 0.001), and PVR (rho = 0.575, P < 0.001). The improvement in the perfusion defect score was significantly associated with improvement in mPAP (rho = 0.844, P < 0.001). Conclusion: Our results suggest that semi-quantitative analysis of lung perfusion SPECT/CT can provide a potential imaging biomarker for monitoring the efficacy of BPA. [ABSTRACT FROM AUTHOR]

Methods: This prospective study included 92 patients who underwent BLVR with quantitative SPECT/CT study pre- and post-procedure between November 2018 and June 2023. The mean age was 70 years (range 56-85). with 51 males and 41 females. SPECT/CT quantified perfusion for each lobe, and the lowest counts/volume ratio determined the procedural target. Postprocedure SPECT/CT assessed total atelectasis and perfusion shifts. The 6-minute walk test and pulmonary function tests were compared pre- and post-BLVR., Results: SPECT/CT-guided BLVR showed clinical benefits (decreased oxygen requirements) and physiological improvements in total lung capacity, forced expiratory volume, and forced vital capacity ( P < 0.05). Significant perfusion shifts were observed away from the target lobe, with unique patterns noted for ipsilateral and contralateral nontarget lobes ( P < 0.05)., Conclusion: Quantitative lobar SPECT/CT in preprocedural guidance for BLVR proved useful in identifying suitable targets in multi-lobe homogeneous emphysema, resulting in physiological and clinical improvements for this patient group. The perfusion shift information provided by SPECT/CT offers valuable insights for pulmonologists., (Copyright © 2024 Wolters Kluwer Health, Inc. All rights reserved.)

Abstract: In preparation for 90 Y radioembolization for hepatic malignancies, hepatic angiography is performed with intra-arterial delivery of 99m Tc-macroaggregated albumin (MAA), known as premapping. This initial procedure allows for evaluation of standard/variant hepatic arterial anatomy using MAA as a surrogate marker for the delivery of 90 Y to visualize the likely distribution of 90 Y. Premapping allows for the assessment of at-risk extrahepatic targets and for the quantification of hepatopulmonary shunting. We present cases where MAA scintigraphic images reveal unusual perfusion patterns in hepatic cancers, treated with 90 Y glass microspheres (Therasphere; Boston Scientific, Marlborough, MA)., Competing Interests: Conflicts of interest and sources of funding: none declared., (Copyright © 2024 Wolters Kluwer Health, Inc. All rights reserved.)

Summary: In patients with a history of melanoma, the risk of recurrence depends on the stage at diagnosis. Patients who present with more advanced disease are more likely to experience recurrence; patients with less advanced disease at presentation have slower progression and lower likelihood of recurrence. The aim of this study was to evaluate the use of a minimally invasive and targeted technique as a diagnostic and therapeutic tool for the excision of nonpalpable lesions suspected to be melanoma metastases. The authors evaluated 21 patients with stage IIB, IIC, or III melanoma and subcutaneous nonpalpable lesions with a high risk of malignancy on positron emission tomography/computed tomography scan during oncologic follow-up. To guide biopsy, the authors used the radioguided occult lesion localization technique, using intralesional injection of technetium-99m albumin macroaggregates the day before surgery. During surgery, a handheld gamma probe was used to locate the lesions. Surgical localization of radiolabeled lesions was achieved in all cases. Relapsed melanoma was histologically confirmed in 13 patients. This technique proved to be a simple, safe, and effective method to detect and biopsy nonpalpable or difficult-to-locate lesions in suspected metastatic melanoma. The main advantage was disease restaging (eg, from stage II to III), allowing patients to access adjuvant therapies not approved as early-stage melanoma treatment., Clinical Question/level of Evidence: Therapeutic, IV., (Copyright © 2023 by the American Society of Plastic Surgeons.)

Abstract: A 51-year-old woman with a 2-mm-Breslow-thickness melanoma on her arm had 99mTc-nanocolloid lymphoscintigraphy to localize the associated sentinel lymph node. A single axillary node was identified, and histology confirmed a micrometastasis of breast tissue origin. Imaging of the patient's breasts and subsequent biopsy confirmed ipsilateral stage III breast cancer, which was treated with lumpectomy and axillary node clearance. This is the first reported case of an incidental solid cancer diagnosis from a sentinel lymph node biopsy undertaken for a different tumor origin. This illustrates the importance of recognizing overlapping lymphatic distribution of sentinel lymph nodes, which can drain multiple organs., Competing Interests: Conflicts of interest and sources of funding: The other authors declare no conflicts of interest. A.R. is supported by a Cancer Research UK/Royal College of Surgeons Clinician Scientist Fellowship (C64667/A27958) and has received honoraria from the Alliance for Cancer Early Detection and the British Association for Plastic, Reconstructive and Aesthetic Surgery., (Copyright © 2024 The Author(s). Published by Wolters Kluwer Health, Inc.)

Background/aim: Surgical resection with a minimally invasive approach is the standard for diagnosing and treating solitary pulmonary nodules. A computed tomography (CT)-guided technetium 99m -macroaggregated albumin ( 99m Tc-MAA) injection-based procedure has been employed for small and non-palpable lung nodule radio-guided preoperative localization (ROLL). This procedure is usually followed by video-assisted thoracoscopic surgery (VATS). This study retrospectively evaluated the feasibility, clinicopathologic outcomes, and complications of this localization radio-guided procedure followed by uniportal VATS., Patients and Methods: This retrospective study included 63 patients with suspicious lung nodules who underwent 99m Tc-MAA CT-guided localization before uniportal VATS. The analysis examined the imaging and procedure characteristics, procedural risks, successful intra-operative localization, wedge resection, conversion from VATS to open thoracotomy, the reason, and histological diagnosis for each nodule. Also, it was evaluated how nodule and procedure features affected successful intra-operative localization., Results: All patients were diagnosed using a CT scan, and 90.4% had a PET scan at basal staging. A round-glass morphology was present in 9.6% of cases, whereas most had a solid appearance. The mean nodule size was 9.78 mm (maximal tumoral diameter) with a 1-23 mm range. The mean distance from the pleural surface was 15.6 mm (range=1-117 mm). The detection rate of the 99m Tc-MAA CT-guided localization procedure was 100%. Surgical procedures were uniportal VATS and transpleural thoracoscopy in 52 (82.5%) and 11 (17.5%) patients, respectively. The intraoperative localization rate was 98.4%. Pneumothorax represented the most frequent complication (6.3%), with one case clinically significant and three only with minimal radiological evidence. Pathology confirmed radical excision in all cases., Conclusion: Lung nodule localization with CT-guided 99m Tc-MAA followed by uniportal VATS is feasible with a high success rate and low complication rate., (Copyright © 2024 International Institute of Anticancer Research (Dr. George J. Delinasios), All rights reserved.)

Purpose: The detection of small lung nodules in thoracoscopic procedure is difficult when the lesions are not located within the outer border of the lung. In the case of ground-glass opacities, it is often impossible to palpate the lesion. Marking lung nodules using a radiotracer is a known technique. We analysed the accuracy and safety of the technique and the potential benefits of operating in a hybrid operating room., Methods: 57 patients, including 33 (58%) females with a median age of 67 years (range 21-82) were included. In 27 patients, we marked and resected the lesion in a hybrid room. In 30 patients, the lesion was marked at the department of radiology the day before resection. [ 99m Tc]Tc-Macrosalb (Pulmocis ® ) was used at an activity of 1 MBq in the hybrid room and at an activity of 3 MBq the day before to get technical feasible results. Radioactivity was detected using the Neoprobe ® detection system., Results: Precise detection and resection of the nodules was possible in 95% of the lesions and in 93% of the patients. Complete thoracoscopic resection was possible in 90% of the patients. Total conversion rate was 10%, but conversion due to failure of the marking of the nodule was observed in only 5% of the patients. Histology revealed 28 (37%) primary lung cancers, 24 (32%) metastases and 21 (28%) benign lesions. In 13 (23%) patients, minor complications were observed. None of them required additional interventions., Conclusion: The radio-guided detection of small pulmonary nodules is very accurate and safe after CT-guided injection of [ 99m Tc]Tc-Macrosalb. Performing the operation in a hybrid room has several logistic advantages and allows using lower technetium-99m activities. The technique allows minimally invasive lung sparing resection and prevents overtreatment of benign and metastatic lesions., (© 2023. The Author(s).)

Background: Magtrace is a supraparamagnetic iron lymphatic tracer that has had increasing use in sentinel node biopsy (SNB) for breast cancer and has theoretical logistical benefits in centres where nanocolloid use may be associated with such issues. We describe our initial experience with the introduction of Magtrace into our routine practice by dual localisation with nanocolloid, comparing performance, and concordance., Materials and Methods: This was prospective study of the first patients undergoing axillary SNB using Magtrace in a single centre. These patients had dual localisation with nanocolloid and Magtrace. Subjective global assessments of Magtrace and nanocolloid performance as well as objective signal strength and anatomical concordance were compared across multiple timepoints in the operative journey., Results: A total of 30 consecutive patients underwent SNB within the timeframe of this study. While there were no failed SNB, 8 issues were reported including 4 issues of perceived imperfect localisation on global assessment. No patient had a failed or abandoned SNB, and only 1 case had a potential challenge in subsequent management after histopathological examination of the retrieved nodes. The majority of these issues occurred in the first half of the study period. There was overall weak to moderate positive correlation between Magtrace and nanocolloid signals of the retrieved sentinel nodes (Spearman's ρ = 0.392, P = .043)., Conclusion: This study suggests that introducing Magtrace was feasible and safe in the context of a rural breast cancer service. A possible strategy to ameliorate the learning curve associated with these procedures is the routine dual localisation in the initial phases of performing Magtrace localisation., Competing Interests: Disclosure There was no specific funding for this study. DM has previously consulted for Endomag and the National Institute of Clinical Excellence (NICE), United Kingdom. The other authors have no conflicts of interests to declare., (Copyright © 2024 The Author(s). Published by Elsevier Inc. All rights reserved.)

Purpose: Significant improvements within radioembolization imaging and dosimetry permit the development of an accurate and personalized pretreatment plan using technetium 99m-labeled macroaggregated albumin ( 99 m Tc-MAA) and single-photon emission computed tomography (SPECT) combined with anatomical CT (SPECT/CT). Despite these potential advantages, the clinical transition to pretreatment protocols with SPECT/CT is hindered by their unknown safety constraints. This study aimed to address this issue by establishing novel dose limits for 99 m Tc-MAA SPECT/CT to enable quantitative pretreatment planning., Methods and Materials: Stratification criteria to determine images most viable for dosimetry analysis were created from a cohort of 85 patients. SPECT/CT, cone beam CT, and activity calculations derived from the local deposition method were used to create an accurate pretreatment protocol. Planar and SPECT/CT images were compared using linear regression and modified Bland-Altman analyses to convert accepted planar dose limits to SPECT/CT. To validate these new dose limits, activity calculations based on SPECT/CT were compared with those calculated with the body surface area and planar methods for three treatment plans., Results: A total of 38 of 85 patients were deemed viable for dosimetry analysis. SPECT yielded greater lung shunt fractions (LSFs) than planar imaging when LSFs were <4.89%, whereas SPECT yielded lower LSFs than planar imaging when LSFs were >4.89%. Planar to SPECT/CT dose conversions were 0.76×, 0.70×, and 0.55× for the whole liver, normal liver, and lungs, respectively. Patients with SPECT LSFs ≤4.89% were safely treated with the direct application of planar lung dose limits. Activity calculations with the newly established SPECT/CT dose limits were greater than those of the body surface area method by a median range of 33.1% to 61.9% and were lower than planar-based activity calculations by a median range of 12.5% to 13.7% for the whole liver and by 29.4% to 32.2% for the normal liver., Conclusions: This study demonstrated a safe method for translating dose limits from 99 m Tc-MAA planar imaging to SPECT/CT. A robust pretreatment protocol was further developed guided by the current knowledge in the field. Established SPECT/CT dose limits safely treated 97.5% of patients and permitted the application of independent pretreatment planning with 99 m Tc-MAA SPECT/CT., (Copyright © 2024 The Author(s). Published by Elsevier Inc. All rights reserved.)

To address the limitations of conventional sentinel lymph node biopsy (SLNB), a novel hybrid tracer (indocyanine green [ICG]- 99m Tc-nanocolloid) has been developed. This meta-analysis aimed to compare the differences between the novel hybrid tracer and conventional methods using ICG or radioisotope (RI) for SLNB in head and neck malignancies. This study was registered in the International Prospective Register of Systematic Reviews (CRD42023409127). PubMed, Embase, Web of Science, and the Cochrane Library were systematically searched. This study included raw data on the number of sentinel lymph nodes (SLNs) identified using different modalities during surgery for head and neck malignancies. The identification rate of SLNs was the main outcome of interest. Prognostic data and complication rate cannot be deduced from this article. The heterogeneity test (I 2 ) determined the use of a fixed- or random-effects model for the pooled risk ratio (RR). Overall, 1275 studies were screened, of which 11 met the inclusion criteria for the meta-analysis. In SLN identification of head and neck malignancies, ICG- 99m Tc-nanocolloid was superior to ICG or RI. In the subgroup analyses, the detection rates of ICG and RI tracers in SLNB were comparable, regardless of the device, tumor type, or tumor stage. In conclusion, in SLN identification of head and neck malignancies, the use of ICG- 99m Tc-nanocolloid is superior to the single technique of ICG or RI. This study suggests that Hospitals using ICG or RI may find it beneficial to change their practice to ICG- 99m Tc-nanocolloid, especially in the head and neck area, owing to its superior effectiveness., Competing Interests: Declaration of competing interest The Authors declare that there is no conflict of interest., (© 2024 Published by Elsevier Ltd.)

Purpose: This study evaluated the effect of an increase in the time interval between hepatic intra-arterial injection of 99m Tc-macroaggregated albumin (MAA) and hepatic artery perfusion scintigraphy (HAPS) on the lung shunt fraction (LSF) and perfused volume (PV) calculations in the treatment planning of selective internal radiation therapy (SIRT). Methods: The authors enrolled 51 HAPS sessions from 40 patients diagnosed with primary or metastatic liver malignancy. All patients underwent scan at the first and fourth hour after hepatic arterial injection of 99m Tc-MAA. Based on single-photon emission computed tomography images, LSF values were measured from each patient's first and fourth hour images. PV1 and PV4 were also calculated based on three-dimensional images using 5% and 10% cutoff threshold values and compared with each other. Results: The authors found that the median of LSF4 was statistically significantly higher than LSF1 (3.05 vs. 4.14, p  ≤ 0.01). There was no statistically significant difference between PV1 and PV4 on the 10% ( p  = 0.72) thresholds. Conclusions: LSF values can be overestimated in case of delayed HAPS, potentially leading to treatment cancellation due to incorrectly high results in patients who could benefit from SIRT. Threshold-based PV values do not significantly change over time; nevertheless, keeping the short interval time would be safer.

Objectives: To compare the efficacy of computed tomography volumetry (CTV), technetium 99m galactosyl-serum-albumin ( 99m Tc-GSA) scintigraphy, and gadolinium-ethoxybenzyl-diethylenetriamine-pentaacetic-acid-enhanced MRI (EOB-MRI) in estimating the liver fibrosis (LF) stage in patients undergoing liver resection., Methods: This retrospective study included 91 consecutive patients who had undergone preoperative dynamic CT and 99m Tc-GSA scintigraphy. EOB-MRI was performed in 76 patients. CTV was used to measure the total liver volume (TLV), spleen volume (SV), normalised to the body surface area (BSA), and liver-to-spleen volume ratio (TLV/SV). 99m Tc-GSA scintigraphy provided LHL15, HH15, and GSA indices. The liver-to-spleen ratio (LSR) was calculated in the hepatobiliary phase of EOB-MRI. Hyaluronic acid and type 4 collagen levels were measured in 65 patients. Logistic regression and receiver operating characteristic (ROC) analyses were performed to identify useful parameters for estimating the LF stage and laboratory data., Results: According to the multivariable logistic regression analysis, SV/BSA (odds ratio [OR], 1.01; 95% confidence interval [CI], 1.003-1.02; p = 0.011), LSR (OR, 0.06; 95%CI, 0.004-0.70; p = 0.026), and hyaluronic acid (OR, 1.01; 95%CI, 1.001-1.02; p = 0.024) were independent variables for severe LF (F3-4). Combined SV/BSA, LSR, and hyaluronic acid correctly estimated severe LF, with an AUC of 0.91, which was significantly larger than the AUCs of the GSA index (AUC = 0.84), SV/BSA (AUC = 0.83), or LSR (AUC = 0.75) alone., Conclusions: Combined CTV, EOB-MRI, and hyaluronic acid analyses improved the estimation accuracy of severe LF compared to CTV, EOB-MRI, or 99m Tc-GSA scintigraphy individually., Clinical Relevance Statement: The combined analysis of spleen volume on CT volumetry, liver-to-spleen ratio on gadolinium-ethoxybenzyl-diethylenetriamine-pentaacetic-acid-enhanced MRI, and hyaluronic acid can identify severe liver fibrosis associated with a high risk of liver failure after hepatectomy and recurrence in patients with hepatocellular carcinoma., Key Points: • Spleen volume of CT volumetry normalised to the body surface area, liver-to-spleen ratio of EOB-MRI, and hyaluronic acid were independent variables for liver fibrosis. • CT volumetry and EOB-MRI enable the detection of severe liver fibrosis, which may correlate with post-hepatectomy liver failure and complications. • Combined CT volumetry, gadolinium-ethoxybenzyl-diethylenetriamine-pentaacetic-acid-enhanced MRI (EOB-MRI), and hyaluronic acid analyses improved the estimation of severe liver fibrosis compared to technetium 99m galactosyl-serum-albumin scintigraphy., (© 2023. The Author(s), under exclusive licence to European Society of Radiology.)

Purpose: Radiation pneumonitis is a serious complication of radioembolization. In holmium-166 ([ 166 Ho]) radioembolization, the lung mean dose (LMD) can be estimated (eLMD) using a scout dose with either technetium-99 m-macroaggregated albumin ([ 99m Tc]MAA) or [ 166 Ho]-microspheres. The accuracy of eLMD based on [ 99m Tc]MAA (eLMD MAA ) was compared to eLMD based on [ 166 Ho]-scout dose (eLMD Ho-scout ) in two prospective clinical studies., Materials and Methods: Patients were included if they received both scout doses ([ 99m Tc]MAA and [ 166 Ho]-scout), had a posttreatment [ 166 Ho]-SPECT/CT (gold standard) and were scanned on the same hybrid SPECT/CT system. The correlation between eLMD MAA /eLMD Ho-scout and LMD Ho-treatment was assessed by Spearman's rank correlation coefficient (r). Wilcoxon signed rank test was used to analyze paired data., Results: Thirty-seven patients with unresectable liver metastases were included. During follow-up, none developed symptoms of radiation pneumonitis. Median eLMD MAA (1.53 Gy, range 0.09-21.33 Gy) was significantly higher than median LMD Ho-treatment (0.00 Gy, range 0.00-1.20 Gy; p < 0.01). Median eLMD Ho-scout (median 0.00 Gy, range 0.00-1.21 Gy) was not significantly different compared to LMD Ho-treatment (p > 0.05). In all cases, eLMD MAA was higher than LMD Ho-treatment (p < 0.01). While a significant correlation was found between eLMD Ho-scout and LMD Ho-treatment (r = 0.43, p < 0.01), there was no correlation between eLMD MAA and LMD Ho-treatment (r = 0.02, p = 0.90)., Conclusion: [ 166 Ho]-scout dose is superior in predicting LMD over [ 99m Tc]MAA, in [ 166 Ho]-radioembolization. Consequently, [ 166 Ho]-scout may limit unnecessary patient exclusions and avoid unnecessary therapeutic activity reductions in patients eligible for radioembolization., Trail Registration: NCT01031784, registered December 2009. NCT01612325, registered June 2012., (© 2024. The Author(s).)

This study aimed to evaluate a deep learning-based attenuation correction (AC) method to generate pseudo-computed tomography (CT) images from non-AC single-photon emission computed tomography images (SPECT NC ) for AC in 99m Tc-galactosyl human albumin diethylenetriamine pentaacetic acid (GSA) scintigraphy and to reduce patient dosage. A cycle-consistent generative network (CycleGAN) model was used to generate pseudo-CT images. The training datasets comprised approximately 850 liver phantom images obtained from SPECT NC and real CT images. The training datasets were then input to CycleGAN, and pseudo-CT images were output. SPECT images with real-time CT attenuation correction (SPECT CTAC ) and pseudo-CT attenuation correction (SPECT GAN ) were acquired. The difference in liver volume between real CT and pseudo-CT images was evaluated. Total counts and uniformity were then used to evaluate the effects of AC. Additionally, the similarity coefficients of SPECT CTAC and SPECT GAN were assessed using a structural similarity (SSIM) index. The pseudo-CT images produced a lower liver volume than the real CT images. SPECT CTAC exhibited a higher total count than SPECT NC and SPECT GAN , which were approximately 60% and 7% lower, respectively. The uniformities of SPECT CTAC and SPECT GAN were better than those of SPECT NC . The mean SSIM value for SPECT CTAC and SPECT GAN was 0.97. We proposed a deep learning-based AC approach to generate pseudo-CT images from SPECT NC images in 99m Tc-GSA scintigraphy. SPECT GAN with AC using pseudo-CT images was similar to SPECT CTAC , demonstrating the possibility of SPECT/CT examination with reduced exposure to radiation., (© 2023. The Author(s), under exclusive licence to Japanese Society of Radiological Technology and Japan Society of Medical Physics.)

Purpose: This study aimed to determine the absorbed doses in the tumoral-liver and non-tumoral liver of hepatocellular carcinoma (HCC) patients undergoing radioembolization with Yttrium-90 ( 90 Y) resin microspheres, and compared with those derived from 99m Tc-MAA using the partition model., Methods: A total of 42 HCC patients (28 males and 14 females, mean age 65 ± 11.51 years) who received 45 treatment sessions with 90 Y-microspheres between 2016 and 2021 were included. Pre-treatment 99m Tc-MAA and post-treatment 90 Y-bremsstrahlung SPECT/CT were acquired for each patient. Semi-automated segmentation of regions of interest (ROIs) was performed using MIM Encore software to determine the tumor-liver ratio (TLR) encompassing the liver volume, tumoral-liver, and lungs, and verified by both nuclear medicine physician and interventional radiologist. A partition dosimetry model was used to estimate the administered activity of 90 Y-microspheres and the absorbed doses to the tumoral-liver and non-tumoral liver. The student's paired t test and Bland-Altman plot were used for the statistical analysis., Results: The mean TLR values obtained from 99m Tc-MAA SPECT/CT and 90 Y-bremsstrahlung SPECT/CT were 4.78 ± 3.51 and 2.73 ± 1.18, respectively. The mean planning administered activity of 90 Y-microspheres based on 99m Tc-MAA SPECT/CT was 1.56 ± 0.80 GBq, while the implanted administered activity was 2.53 ± 1.23 GBq (p value < 0.001). The mean absorbed doses in the tumoral-liver estimated from 99m Tc-MAA and 90 Y-bremsstrahlung SPECT/CT were 127.44 ± 4.36 Gy and 135.98 ± 6.30 Gy, respectively. The corresponding mean absorbed doses in the non-tumoral liver were 34.61 ± 13.93 Gy and 55.04 ± 16.36 Gy., Conclusion: This study provides evidence that the administered activity of 90 Y-microspheres, as estimated from 90 Y-bremsstrahlung SPECT/CT, was significantly higher than that estimated from 99m Tc-MAA SPECT/CT resulted in increased absorbed doses in both the tumoral-liver and non-tumoral liver. However, 99m Tc-MAA SPECT/CT remains a valuable planning tool for predicting the distribution of 90 Y-microspheres in liver cancer treatment., (© 2023. The Author(s) under exclusive licence to The Japanese Society of Nuclear Medicine.)

The hepatopulmonary syndrome (HPS) is characterized by arterial oxygenation defect induced by intrapulmonary vascular dilatations in the setting of liver disease. We report a 57-year-old woman with a history of liver cirrhosis presented with progressive cyanosis, exertional dyspnea and a dry cough. Oxyhemoglobin saturation was 88.5% on room air. Contrast transthoracic echocardiography (cTTE) and technetium-99m-macroaggregated albumin ( 99m Tc-MAA) scintigraphy showed an intrapulmonary shunting and confirmed HPS.

Purpose: To calculate the preradioembolic tumor-to-normal (T:N) ratio in hepatocellular carcinoma (HCC) using 2-dimensional (2D) perfusion angiography and compare it with that calculated using technetium-99m macroaggregated albumin ( 99m Tc MAA) single-photon emission computed tomography (SPECT)/computed tomography (CT)., Materials and Methods: This prospective single-arm study enrolled 15 participants with HCC who underwent 2D perfusion angiography immediately before the enrollment and with the microcatheter located at the same location as 99m Tc MAA injection, after which SPECT/CT was performed. Quantitative digital subtraction angiography was used to calculate the area under the curve for the tumor and normal hepatic parenchyma and subsequently calculate the T:N ratio. The T:N ratio was calculated from the 99m Tc MAA SPECT/CT and post-yttrium-90 bremsstrahlung SPECT/CT using dosimetry software., Results: The mean participant age was 64.1 years ± 9.8, and the study included 14 (93%) men and 1 (7%) woman. The mean tumor size was 4.1 cm (SD ± 2.4), and all participants received segmental treatments with glass microspheres. The mean T:N ratio calculated by 99m Tc MAA SPECT/CT was 2.28 (SD ± 0.89) vs 2.25 (SD ± 0.99) calculated by 2D perfusion angiography (P = .45). For the 13 participants who underwent selective internal radiation therapy (transarterial radioembolization), there was no significant difference between the T:N ratios calculated by 2D perfusion angiography and post- 90 Y SPECT/CT (2.25 [SD ± 1.05] vs 1.91 [SD ± 0.39]; P = .12)., Conclusions: The T:N ratio calculated by 2D perfusion angiography correlated well with that calculated by 99m Tc MAA SPECT/CT., (Copyright © 2023 SIR. Published by Elsevier Inc. All rights reserved.)

Introduction: The most important toxicity of transarterial radioembolization therapy applied in liver malignancies is radiation pneumonitis and fibrosis due to hepatopulmonary shunt of Yttrium-90 ( 90 Y) microspheres. Currently, Technetium-99m macroaggregated albumin ( 99m Tc-MAA) scintigraphic images are used to estimate lung shunt fraction (LSF) before treatment. The aim of this study was to create a phantom to calculate exact LFS rates according to 99m Tc activities in the phantom and to compare these rates with LSF values calculated from scintigraphic images., Materials and Methods: A 3D-printed lung and liver phantom containing two liver tumors was developed from Polylactic Acid (PLA) material, which is similar to the normal-sized human body in terms of texture and density. Actual %LSFs were calculated by filling phantoms and tumors with 99m Tc radionuclide. After the phantoms were placed in the water tank made of plexiglass material, planar, SPECT, and SPECT/CT images were obtained. The actual LSF ratio calculated from the activity amounts filled into the phantom was used for the verification of the quantification of scintigraphic images and the results obtained by the Simplicity 90 Y TM method., Results: In our experimental model, LSFs calculated from 99m Tc activities filled into the lungs, normal liver, small tumor, and large tumor were found to be 0%, 6.2%, 10.8%, and 16.9%. According to these actual LSF values, LSF values were calculated from planar, SPECT/CT (without attenuation correction), and SPECT/CT (with both attenuation and scatter correction) scintigraphic images of the phantom. In each scintigraphy, doses were calculated for lung, small tumor, large tumor, normal liver, and Simplicity 90 Y TM . The doses calculated from planar and SPECT/CT (NoAC+NoSC) images were found to be higher than the actual doses. The doses calculated from SPECT/CT (with AC+with SC) images and Simplicity 90 Y TM were found to be closer to the real dose values., Conclusion: LSF is critical in dosimetry calculations of 90 Y microsphere therapy. The newly introduced hepatopulmonary shunt phantom in this study is suitable for LSF verification for all models/brands of SPECT and SPECT/CT devices., (Copyright© Bentham Science Publishers; For any queries, please email at epub@benthamscience.net.)

Purpose of the Report: Localization techniques are needed to facilitate resection of nonpalpable lesions. In this study, the feasibility of radio-guided occult lesion localization (ROLL) with 99m Tc is investigated for the localization of nonpalpable, small, suspicious, or proven melanoma or soft tissue sarcoma lesions at various locations throughout the body., Patients and Methods: Patients with nonpalpable, suspicious, or proven melanoma or soft tissue sarcoma lesions were selected for this study. Within 24 hours before surgery, a median dose of 33.92 MBq 99m Tc-labeled human albumin particles ( 99m Tc-NA or 99m Tc-MAA) was injected in the lesion under ultrasound guidance. A hand-held gamma probe was used to detect the radioactive signal and guidance during surgery., Results: In this study, 20 patients with a total of 25 lesions were included and analyzed. The median size of the lesions was 1.8 cm (interquartile range [IQR], 1.8-4.0 cm), of which 44% were intramuscular located and 36% were subcutaneous, and 20% consisted of suspicious lymph nodes, mostly in the lower extremity. At median 4 hours (IQR, 3-6 hours) postinjection, 99m Tc ROLL showed a 100% intraoperative identification rate with proper signal identification with the gamma probe in all patients. With a median surgery time of 76 minutes (IQR, 45-157 minutes), all targeted lesions could be resected without 99m Tc-related complications, resulting in 88% microscopically margin-negative resection. No reoperations were needed for the same lesion., Conclusions: The 99m Tc ROLL procedure is feasible for the localization and excision of small, nonpalpable melanoma and soft tissue sarcoma lesions at various locations in the body., Competing Interests: Conflicts of interest and sources of funding: none declared., (Copyright © 2023 Wolters Kluwer Health, Inc. All rights reserved.)

Background: The objective was to carry out a prospective study to compare the current extended pelvic lymph node dissection (ePLND) to the sentinel node (SN) technique with 99m Tcnanocolloid., Methods: We conducted a prospective study between January 2013 and May 2020. In the first 74 patients, 99m Tc-nanocolloid was used. Then from June 2017 onwards, in 38 patients we used a combined radiotracer prepared by adding indocyanine green (ICG). A preoperative SPECT/CT was also performed to check on the SNs. We extracted the SNs guided by a laparoscopic gamma-ray detection probe and/or a fluorescence camera., Results: We included 112 patients with a Briganti nomogram-assessed risk of 5% or more. In 4 out of the total, the radiotracer did not migrate. The mean number of extracted nodes was 21.56 (13.46-29.71) and the mean of extracted SNs was 5.17 (1.83-8.51) (P<0.001). The technique that registered the most nodes with high activity was SPECT/CT, with an average of 4.33 nodes (2.42-6.23) (P<0.001). We found SNs outside the template in 78% of the patients. A total of 46% of the complications were related to ePLND. The SN biopsy showed a sensitivity of 100%, specificity of 97.5%, PVV of 92.86%, and NPV of 100%., Conclusions: Our results prove that ePLND is a technique with significant morbidity; up to 46% of the complications were related to the ePLND. The SN surgery showed great accuracy in detecting metastases due to the SPECT/CT and a lower rate of complications than ePLND.

Purpose: Near-infrared fluorescence imaging using indocyanine green (ICG) combined with radioactive markers has the potential to improve sentinel lymph-node (SLN) mapping in oral squamous cell carcinoma (OSCC). This study aimed to evaluate the ability of 99m Tc and ICG in identifying the sentinel lymph nodes in patients with early stage OSCC., Methods: Data were collected prospectively, and a retrospective analysis of 15 patients with early stage OSCC and a cN0 neck was performed. All patients received peritumoral injection of 99m Tc the day before surgery and ICG was administered intraoperatively. Intentionally, the application of the two different tracers were done by two different physicians with varying degrees of experience. The number of identified lymph nodes positive for 99m Tc and ICG, the overlap or possible discrepancies of both methods, and the time until fluorescence signals of ICG were detected were noted., Results: In all patients, a 100% agreement in sentinel lymph-node identification was achieved, regardless of both the exact location of the peritumoral injection and the experience of the injecting surgeon. Time until ICG accumulation in the sentinel lymph node was consistently found to be between 1 and 3 min., Conclusion: ICG constitutes a viable and useful addition to 99m Tc for intraoperative sentinel lymph-node detection in this study., (© 2023. The Author(s).)

Purpose: To characterize estimated absorbed tumor dose (AD T ), objective response (OR), and estimated target dose of liver metastatic colorectal cancer (mCRC) after resin microsphere yttrium-90 ( 90 Y) radioembolization using partition dosimetry., Materials and Methods: In this retrospective, single-center study, multicompartment dosimetry of index tumors undergoing 90 Y radioembolization from October 2013 to July 2022 was performed using MIM SurePlan and pretreatment technetium-99m macroaggregated albumin infusion data. Thirty-eight patients with mCRC underwent treatments for 59 index tumors. Patients were imaged every 2-3 months after treatment and then every 3-6 months after disease control to determine the best response per Response Evaluation Criteria in Solid Tumors 1.1. Responses were categorized as OR or nonresponse (NR). A Cox proportional hazards model evaluated the probability of tumor OR and local progression-free survival (LPFS) based on AD T ., Results: Patients had a median follow-up of 116 days (interquartile range [IQR], 69-231 days). The AD T was higher for OR patients than for NR patients (median, 130.8 [IQR, 85.6-239.0] vs 40.6 [IQR, 26.0-66.3] Gy; P < .001). A greater percentage of OR than NR patients were treated with activities calculated by partition modeling (54% vs 12%; P = .005). Only AD T predicted response (P = .032). At 6 months, an AD T of 120 Gy predicted a 55% (95% CI, 0.0%-89%) probability of OR. Only AD T (P = .010) and female sex (P = .014) predicted LPFS. At 1 year, an AD T of 120 Gy predicted a 70% (95% CI, 35%-100%) probability of LPFS., Conclusions: Tumor dose was the strongest predictor of OR for mCRC. Administration of an estimated 120 Gy to mCRC predicted 55% OR with 90 Y resin microspheres at 6 months., (Copyright © 2023 SIR. Published by Elsevier Inc. All rights reserved.)

Purpose: Investigate reproducibility of two segmentation methods for multicompartment dosimetry, including normal tissue absorbed dose (NTAD) and tumour absorbed dose (TAD), in hepatocellular carcinoma patients treated with yttrium-90 ( 90 Y) glass microspheres., Methods: TARGET was a retrospective investigation in 209 patients with < 10 tumours per lobe and at least one tumour ≥ 3 cm ± portal vein thrombosis. Dosimetry was compared using two distinct segmentation methods: anatomic (CT/MRI-based) and count threshold-based on pre-procedural 99m Tc-MAA SPECT. In a round robin substudy in 20 patients with ≤ 5 unilobar tumours, the inter-observer reproducibility of eight reviewers was evaluated by computing reproducibility coefficient (RDC) of volume and absorbed dose for whole liver, whole liver normal tissue, perfused normal tissue, perfused liver, total perfused tumour, and target lesion. Intra-observer reproducibility was based on second assessments in 10 patients ≥ 2 weeks later., Results: 99m Tc-MAA segmentation calculated higher absorbed doses compared to anatomic segmentation (n = 209), 43.9% higher for TAD (95% limits of agreement [LoA]: - 49.0%, 306.2%) and 21.3% for NTAD (95% LoA: - 67.6%, 354.0%). For the round robin substudy (n = 20), inter-observer reproducibility was better for anatomic (RDC range: 1.17 to 3.53) than 99m Tc-MAA SPECT segmentation (1.29 to 7.00) and similar between anatomic imaging modalities (CT: 1.09 to 3.56; MRI: 1.24 to 3.50). Inter-observer reproducibility was better for larger volumes. Perfused normal tissue volume RDC was 1.95 by anatomic and 3.19 by 99m Tc-MAA SPECT, with corresponding absorbed dose RDC 1.46 and 1.75. Total perfused tumour volume RDC was higher, 2.92 for anatomic and 7.0 by 99m Tc-MAA SPECT with corresponding absorbed dose RDC of 1.84 and 2.78. Intra-observer variability was lower for perfused NTAD (range: 14.3 to 19.7 Gy) than total perfused TAD (range: 42.8 to 121.4 Gy)., Conclusion: Anatomic segmentation-based dosimetry, versus 99m Tc-MAA segmentation, results in lower absorbed doses with superior reproducibility. Higher volume compartments, such as normal tissue versus tumour, exhibit improved reproducibility., Trial Registration: NCT03295006., (© 2023. The Author(s).)

Background: The calculation of the net administered activity (A admin ) in patients undergoing 90 Y-radioembolization is essential for dosimetry and radiation safety, yet current methods for measuring residual 90 Y activity are often associated with high uncertainty. Therefore, an accurate, robust, and clinically viable method for the determination of A admin across approved 90 Y microsphere devices is desirable., Purpose: We report on a novel method to determine A admin by leveraging the quantitative capabilities of SPECT/CT to measure 90 Y-emission in vivo from patients following 90 Y-radioembolization with glass or resin microspheres., Methods: 90 Y-SPECT/CT attenuation-corrected count data from 147 sequential 90 Y-radioembolization patients was used for this analysis. A admin was calculated as part of routine clinical practice via the exposure rate differences between the initial 90 Y-vial and the 90 Y-residual jar. This served as our gold standard measure of A admin . Patient data for each microsphere device were separated into training and testing cohorts to first develop regression models and then to independently assess model performance. The training cohorts were divided into four groups: first, based on the microsphere device (glass or resin), and second, based on the SPECT volume used to calculate counts (the full SPECT field of view (FOV) or liver only (VOI liver )). Univariate linear regression models were generated for each group to predict A admin based on 90 Y-SPECT data from the training cohorts. Leave-one-out cross validation was implemented to estimate variability in model parameters. To assess performance, linear models derived from the training cohort were applied to 90 Y-SPECT data from the testing cohort. A comparison of the models between microspheres devices was also performed., Results: Linear models derived from the glass and resin training cohorts demonstrated a strong, positive correlation between 90 Y-SPECT image counts and A admin for VOI liver and FOV with R 2  > 0.98 in all cases. In the glass training cohort, model accuracy (100%-absolute mean prediction error) and precision (95% prediction intervals of mean prediction error) were 99.0% and 15.4% for the VOI liver and 99.7% and 17.5% for the FOV models, respectively. In the resin training cohort, the corresponding values were 98.6% and 16.7% for VOI liver and > 99.9% and 11.4% for the FOV models, respectively. The application of these linear models to 90 Y-SPECT data from the testing cohort showed A admin prediction errors to have high accuracy and precision for both microsphere devices. For the glass testing cohort, accuracy (precision) was 96.9% (19.6%) and 98.8% (21.1%) for the VOI liver and FOV models, respectively. The corresponding values for the resin training cohort were 97.3% (26.2%) and 98.5% (25.7%) for the VOI liver and FOV models, respectively. The slope of the linear models between the two microsphere devices was observed to be significantly different with resin microspheres generating 48%-49% more SPECT counts for equivalent 90 Y activity based on each device manufacturer's activity calibration process., Conclusion: 90 Y-SPECT image counts can reliably predict (accuracy > 95% and precision < 18%) A admin after 90 Y-radioembolization, with performance characteristics essentially equivalent for both glass and resin microspheres. There is a clear indication that activity calibrations are fundamentally different between the two microsphere devices., (© 2023 American Association of Physicists in Medicine.)

A 60-year-old lady with alcoholic liver disease developed central cyanosis and orthodeoxia. A technetium-99m macro-aggregated albumin lung perfusion scan and contrast echocardiogram were performed. A 13% right to left shunt was calculated from the macro-aggregated albumin scan. There were more bubbles in the left heart than the right at the end of the contrast echocardiogram. Hepatopulmonary syndrome was therefore diagnosed. The patient had a liver transplant five days after these investigations. Further discussion about hepatopulmonary syndrome will be provided. Normally, macro-aggregated albumin scans are performed in few centers, however as this was at the height of the coronavirus pandemic, the scan needed to be performed locally to reduce the chance of the patient getting coronavirus. Local radiographers were remotely instructed on conducting the macro-aggregated albumin scan by a larger center to provide a timely and important investigation in a logistically difficult scenario., Competing Interests: DISCLOSURES: Neither author has any interest to declare. No funding was received for this work., (Copyright Journal of Radiology Case Reports.)

Pulmonary embolism is one of the acute diseases of the respiratory system. This study investigates changes in red blood cell counts in pulmonary embolisms confirmed by scintigraphy. Counting red blood cells is essential in diseases, especially pulmonary embolism, because of the vital role of these cells.  In this study, 25 patients with pulmonary embolism were selected. A group of 25 healthy volunteers was also considered as a control. At zero, 30, 60 minutes, 24, 48, and 72 hours, blood samples were taken from both control and patient groups, and red blood cells were counted according to the standard method. After extracting technetium-99m from the molybdenum generator, this substance was added to the MAA drug kit under particular conditions. After preparation, radiopharmaceutical 99mTC-MAA with 1.5 millicuries was injected intravenously into both groups. In this study, a significant increase in the red blood cell count of the patient group was observed on the first and second days of the disease. On the third day, this count returned to normal. These changes indicate the functioning of the body's defense system and a response to reduce the complications caused by pulmonary embolism. Therefore, paying more attention to counting red blood cells in pulmonary embolism, along with other care, is recommended due to their particular function.

Bilateral pulmonary arteriovenous malformations (AVMs) are rare and are often associated with the hereditary hemorrhagic telangiectasia (HHT/Osler–Weber–Rendu) syndrome. We present a woman who presented with neurological symptoms due to a cerebral abscess. On further evaluation, bilateral pulmonary AVMs were identified. The patient was diagnosed with HHT, based on positive family history and multiple cerebral AVMs recognized on subsequent catheter angiogram, in addition to the presence of bilateral pulmonary AVMs. Craniotomy with drainage of the brain abscess and endovascular embolization of the pulmonary AVMs was offered to the patient. As a preembolization work-up, the patient underwent nuclear lung perfusion scan with technetium-99m macroaggregated albumin (Tc-99m MAA) to assess the right-to-left shunt secondary to the pulmonary AVMs. Postembolization follow-up perfusion scan was also obtained to estimate the hemodynamic response. The case is presented to describe the role of Tc-99m MAA perfusion lung scan in preoperatively evaluating patients with pulmonary AVMs and to emphasize on the scan's utility in posttreatment follow-up. Various present day usages of the Tc-99m MAA lung perfusion scan, other than diagnosing pulmonary thromboembolism, are discussed. Providing background knowledge on the physiological and hemodynamic aspects of the Tc-99m MAA lung perfusion scan is also attempted. Various imaging pitfalls and necessary precautions while performing Tc-99m MAA lung perfusion scan are highlighted.

Abstract: In a 51-year-old woman affected by breast cancer, hepatic recurrence of disease was managed by concurrent 90 Y-labeled glass microsphere embolization (transarterial radioembolization) and radiofrequency thermoablation. Intention-to-treat target, candidate to radioembolization, was in the IV hepatic segment; another lesion, managed with radiofrequency thermoablation, was in the VI-VII hepatic segment. Concomitant correction of a duodenocephalopancreatic shunting was performed as well. Thermoablation did not interfere with distribution of 99m Tc-macroaggregated albumin and 90 Y-labeled microspheres to the target and healthy liver. At our knowledge, this is the first report that combines 2 locoregional procedures in different hepatic segments on the same day., Competing Interests: Conflicts of interest and sources of funding: none declared., (Copyright © 2023 Wolters Kluwer Health, Inc. All rights reserved.)

Purpose: The purpose of this study was to evaluate the residual radioactivity in the syringe and route of administration of a low fluid volume 99m Tc-macro aggregated albumin (MAA) intended for pediatric nuclear medicine examinations., Method: We evaluated the residual characteristics, as the effect of elapsed time from drawing up of radiopharmaceuticals to plastic syringe to administration, and the effect of volume of 99m TcO 4 - solution to be labeled, the effect of rinsed times of plastic syringe, effect of dose of calculated by consensus guidelines for pediatric nuclear medicine and residual location in injection sets with 99m Tc-MAA. Residual radioactivity was measured using planar images obtained by the gamma camera., Results: Residual radioactivity rate of 99m Tc-MAA, 99m Tc-MAG 3 , 123 I-IMP showed 41.3±1.6%, 14.4±0.6%, 14.6±2.0%, respectively. 99m Tc-MAA clearly showed a higher residual rate. Residual radioactivity rate increased with the extension of the elapsed time, and reached a high value of 41.3% in 30 minutes. Residual radioactivity rate was dependent on the different volume of 99m TcO 4 - to be labeled (4.0 ml and 8.0 ml). Residual radioactivity rate did not change when the number of rinsed was more than one. Residual rate was around 40% at all doses of calculated by consensus guidelines for pediatric nuclear medicine., Conclusion: 99m Tc-MAA showed the highest residual radioactivity rate among radiopharmaceuticals used in pediatric nuclear medicine examinations. The factor that most affected the residual radioactivity rate of 99m Tc-MAA was the elapsed time from draw up to the plastic syringe to administration.

First-line selective internal radiation therapy (SIRT) showed promising outcomes in patients with uveal melanoma liver metastases (UMLM). Patient survival depends on liver's disease control. SIRT planning is essential and little is known about dosimetry. We investigated whether 99m Tc-MAA-SPECT/CT dosimetry could predict absorbed doses (AD) evaluated on 90 Y-PET/CT and assess the dose-response relationship in UMLM patients treated with first-line SIRT. This IRB-approved, single-center, retrospective analysis (prospectively collected cohort) included 12 patients (median age 63y, range 43-82). Patients underwent MRI/CT, 18 F-FDG-PET/CT before and 3-6 months post-SIRT, and 90 Y-PET/CT immediately post-SIRT. Thirty-two target lesions were included. AD estimates in tumor and non-tumor liver were obtained from 99m Tc-MAA-SPECT/CT and post-SIRT 90 Y-PET/CT, and assessed with Lin's concordance correlation coefficients (ρ c and C b ), Pearson's coefficient correlation (ρ), and Bland-Altman analyses (mean difference ± standard deviation; 95% limits-of-agreement (LOA)). Influence of tumor characteristics and microsphere type on AD was analyzed. Tumor response was assessed according to size-based, enhancement-based and metabolic response criteria. Mean target lesion AD was 349 Gy (range 46-1586 Gy). Concordance between 99m Tc-MAA-SPECT/CT and 90 Y-PET/CT tumor dosimetry improved upon dose correction for the recovery coefficient (RC) (ρ = 0.725, ρ c  = 0.703, C b  = 0.969) with good agreement (mean difference: - 4.93 ± 218.3 Gy, 95%LOA: - 432.8-422.9). Without RC correction, concordance was better for resin microspheres (ρ = 0.85, ρ c  = 0.998, C b  = 0.849) and agreement was very good between predictive 99m Tc-MAA-SPECT/CT and 90 Y-PET/CT dosimetry (mean difference: - 4.05 ± 55.9 Gy; 95%LOA: - 113.7-105.6). After RC correction, 99m Tc-MAA-SPECT/CT dosimetry overestimated AD (- 70.9 ± 158.9 Gy; 95%LOA: - 382.3-240.6). For glass microspheres, concordance markedly improved with RC correction (ρ = 0.790, ρ c  = 0.713, C b  = 0.903 vs without correction: ρ = 0.395, ρ c  = 0.244, C b  = 0.617) and 99m Tc-MAA-SPECT/CT dosimetry underestimated AD (148.9 ± 267.5 Gy; 95%LOA: - 375.4-673.2). For non-tumor liver, concordance was good between 99m Tc-MAA-SPECT/CT and 90 Y-PET/CT dosimetry (ρ = 0.942, ρ c  = 0.852, C b  = 0.904). 99m Tc-MAA-SPECT/CT slightly overestimated liver AD for resin (3.4 ± 3.4 Gy) and glass (11.5 ± 13.9 Gy) microspheres. Tumor AD was not correlated with baseline or post-SIRT lesion characteristics and no dose-response threshold could be identified. 99m Tc-MAA-SPECT/CT dosimetry provides good estimates of AD to tumor and non-tumor liver in UMLM patients treated with first-line SIRT., (© 2023. Springer Nature Limited.)

Background: Management of small lymph nodes or lesions in dense nodal basins found on Positron Emission Tomography (PET) scans can be challenging to identify, access and locate intraoperatively. Herein we describe the first reported case series utilizing pre-operative CT-guided radionuclide-tagged macro-aggregated albumin (TC 99m MAA) for localization and resection of extra-pulmonary PET-avid lymph nodes in pediatric cancer patients., Methods: Pediatric cancer patients (≤21 years) who underwent pre-operative TC 99m MAA localization of suspicious lymph nodes were identified and retrospectively reviewed., Results: Ten procedures were performed on 10 children at our institution from 2017 to 2021. Median age was 14 [13, 18]; 70% were male. Primary tumor type was variable. Lymph nodes were in various nodal basins including the axilla, groin, neck, popliteal fossa, retroperitoneum, and mediastinum. Three patients underwent resection of both pulmonary and extra-pulmonary lesions during the same procedure. Median node size was 15 mm (range: 10 mm- 23 cm). In 60.0% of patients the localized lymph nodes of concern were non-palpable at the time of operation. In 90% of the patient, biopsy findings changed the course of disease management., Conclusion: Pre-operative labeling with TC 99m MAA is a safe and effective technique to facilitate the localization, biopsy, and resection of suspicious lymph nodes found on PET scans in pediatric cancer patients that are located in dense nodal basins. This technique enables accurate resection of small, concerning lymph nodes that might otherwise be difficult to operatively identify and excise; the resultant information can affect the staging and further treatment of these patients., Level of Evidence: IV., Competing Interests: Conflicts of interest None for any authors., (Copyright © 2022 Elsevier Inc. All rights reserved.)

Background: Lymph node (LN) metastasis is a relevant predictor for survival in patients with a.o. penile cancer (PeCa), malignant melanoma. The sentinel node (SN) procedure comprises targeted resection of the first tumour-draining SNs. Here, the hybrid tracer indocyanine green (ICG)- 99m Tc-nanocolloid has been used for several years to combine optical and nuclear detection. Recently, the resource of the nanocolloid precursor stopped production and the precursor was replaced by a different but chemically comparable colloid, nanoscan. Our aim was to study the performance of ICG- 99m Tc-nanoscan compared to ICG- 99m Tc-nanocolloid from a nuclear and surgical perspective., Methods: Twenty-four patients with either PeCa or head-and-neck (H&N) melanoma and scheduled for a SN procedure were included. The initial group (n = 11) received ICG- 99m Tc-nanocolloid until no longer available; the second group (n = 13) received ICG- 99m Tc-nanoscan. Tracer uptake was assessed on lymphoscintigraphy and single-photon emission (SPECT). Intraoperatively, SNs were identified using gamma tracing and fluorescence imaging. Ex vivo (back-table) measurements were conducted to quantify the fluorescence emissions. Chemical analysis was performed to compare the ICG assembly on both precursors., Results: The mean tracer uptake in the SNs was similar for ICG- 99m Tc-nanocolloid (2.2 ± 4.3%ID) and ICG- 99m Tc-nanoscan (1.8 ± 2.6%ID; p = 0.68). 3 SNs (interquartile range (IQR) 3-4) were detected on lymphoscintigraphy in PeCa patients receiving ICG- 99m Tc-nanoscan compared to 2 SNs (IQR 2-3) in PeCa patients receiving ICG- 99m Tc-nanocolloid (p = 0.045), no differences were observed in H&N patients. Back-table measurements of resected SNs revealed a lower total fluorescence intensity in the ICG- 99m Tc-nanoscan group (24*10 9 arbitrary units (A.U) IQR 1.6*10 9 -14*10 9 in the ICG- 99m Tc-nanocolloid group versus 4.6*10 9 A.U. IQR 2.4*10 9 -42*10 9 in the ICG- 99m Tc-nanoscan group, p = 0.0054). This was consistent with a larger degree of "stacked" ICG observed in the nanoscan formulation. No tracer-related adverse events were reported., Conclusions: Based on this retrospective analysis, we can conclude that ICG- 99m Tc-nanoscan has similar capacity for SN identification as ICG- 99m Tc-nanocolloid and can safely be implemented in SN procedures., (© 2023. The Author(s).)

Purpose: Respiration and body movement induce misregistration between static [ 99m Tc]Tc-MAA SPECT and CT, causing lung shunting fraction (LSF) and tumor-to-normal liver ratio (TNR) errors for 90 Y radioembolization planning. We aim to alleviate the misregistration between [ 99m Tc]Tc-MAA SPECT and CT using two registration schemes on simulation and clinical data., Methods: In the simulation study, 70 XCAT phantoms were modeled. The SIMIND Monte Carlo program and OS-EM algorithm were used for projection generation and reconstruction, respectively. Low-dose CT (LDCT) at end-inspiration was simulated for attenuation correction (AC), lungs and liver segmentation, while contrast-enhanced CT (CECT) was simulated for tumor and perfused liver segmentation. In the clinical study, 16 patient data including [ 99m Tc]Tc-MAA SPECT/LDCT and CECT with observed SPECT and CT mismatch were analyzed. Two liver-based registration schemes were studied: SPECT registered to LDCT/CECT and vice versa. Mean count density (MCD) of different volumes-of-interest (VOIs), normalized mutual information (NMI), LSF, TNR, and maximum injected activity (MIA) based on the partition model before and after registration were compared. Wilcoxon signed-rank test was performed., Results: In the simulation study, compared to before registration, registrations significantly reduced estimation errors of MCD of all VOIs, LSF (Scheme 1: - 100.28%, Scheme 2: - 101.59%), and TNR (Scheme 1: - 7.00%, Scheme 2: - 5.67%), as well as MIA (Scheme 1: - 3.22%, Scheme 2: - 2.40%). In the clinical study, Scheme 1 reduced 33.68% LSF and increased 14.75% TNR, while Scheme 2 reduced 38.88% LSF and increased 6.28% TNR compared to before registration. One patient may change from 90 Y radioembolization untreatable to treatable and other patients may change the MIA up to 25% after registration. NMI between SPECT and CT was significantly increased after registrations in both studies., Conclusion: Registration between static [ 99m Tc]Tc-MAA SPECT and corresponding CTs is feasible to reduce their spatial mismatch and improve dosimetric estimation. The improvement of LSF is larger than TNR. Our method can potentially improve patient selection and personalized treatment planning for liver radioembolization., (© 2023. The Author(s), under exclusive licence to Springer-Verlag GmbH Germany, part of Springer Nature.)

Objective: To determine the diagnostic accuracy of the hybrid tracer indocyanine green (ICG)-Technetium-99 m( 99m Tc)-nanocolloid compared to sequential tracers of 99m Tc-nanocolloid and free-ICG in detecting tumor-positive lymph nodes (LN) during primary surgery in prostate cancer (PCa) patients., Introduction: Image-guided surgery strategies can help visualize individual lymphatic drainage patterns and sentinel lymph nodes (SLNs) in PCa patients. For lymphatic mapping radioactive, fluorescent and hybrid tracers are being clinically exploited. In this prospective randomized phase II trial, we made a head-to-head comparison between ICG- 99m Tc-nanocolloid (hybrid group) and 99m Tc-nanocolloid and subsequent free-ICG injection (sequential group)., Methods: PCa patients with a  >5% risk of lymphatic involvement according to the 2012 Briganti nomogram and planned for prostatectomy were included and randomized (1:1) between ultrasound-guided intraprostatic tracer administration of ICG- 99m Tc-nanocolloid (n = 69) or 99m Tc-nanocolloid (n = 69) 5 h before surgery. Preoperative lymphoscintigraphy and SPECT/CT were performed to define the locations of the SLNs. Additionally, all participants in the sequential group received an injection of free-ICG at time of surgery. Subsequently, all (S)LNs were dissected using fluorescence guidance followed by an extended pelvic lymph node dissection (ePLND). The primary outcome was the total number of surgically removed (S)LNs and tumor-positive (S)LNs., Results: The total number of surgically removed (S)LN packages was 701 and 733 in the hybrid and sequential groups, respectively (p = 0.727). The total number of fluorescent LNs retrieved was 310 and 665 nodes in the hybrid and sequential groups, respectively (p < 0.001). However, no statistically significant difference was observed in the corresponding number of tumor-positive nodes among the groups (44 vs. 33; p = 0.470). Consequently, the rate of tumor-positive fluorescent LNs was higher in the hybrid group (7.4%) compared to the sequential group (2.6%; p = 0.002), indicating an enhanced positive predictive value for the hybrid approach. There was no difference in complications within 90 days after surgery (p = 0.78)., Conclusions: The hybrid tracer ICG- 99m Tc-nanocolloid improved the positive predictive value for tumor-bearing LNs while minimizing the number of fluorescent nodes compared to the sequential tracer approach. Consequently, the hybrid tracer ICG- 99m Tc-nanocolloid enables the most reliable and minimal invasive method for LN staging in PCa patients., (© 2023. The Author(s), under exclusive licence to Springer-Verlag GmbH Germany, part of Springer Nature.)