Y-90 PET/MR imaging optimization with a Bayesian penalized likelihood reconstruction algorithm.

Positron Emission Tomography (PET) imaging after 90 Y liver radioembolization is used for both lesion identification and dosimetry. Bayesian penalized likelihood (BPL) reconstruction algorithms are an alternative to ordered subset expectation maximization (OSEM) with improved image quality and lesion detectability. The investigation of optimal parameters for 90 Y image reconstruction of Q.Clear, a commercial BPL algorithm developed by General Electric (GE), in PET/MR is a field of interest and the subject of this study. The NEMA phantom was filled at an 8:1 sphere-to-background ratio. Acquisitions were performed on a PET/MR scanner for clinically relevant activities between 0.7 and 3.3 MBq/ml. Reconstructions with Q.Clear were performed varying the ß penalty parameter between 20 and 6000, the acquisition time between 5 and 20 min and pixel size between 1.56 and 4.69 mm. OSEM reconstructions of 28 subsets with 2 and 4 iterations with and without Time-of-Flight (TOF) were compared to Q.Clear with ß = 4000. Recovery coefficients (RC), their coefficient of variation (COV), background variability (BV), contrast-to-noise ratio (CNR) and residual activity in the cold insert were evaluated. Increasing ß parameter lowered RC, COV and BV, while CNR was maximized at ß = 4000; further increase resulted in oversmoothing. For quantification purposes, ß = 1000-2000 could be more appropriate. Longer acquisition times resulted in larger CNR due to reduced image noise. Q.Clear reconstructions led to higher CNR than OSEM. A ß of 4000 was obtained for optimal image quality, although lower values could be considered for quantification purposes. An optimal acquisition time of 15 min was proposed considering its clinical use.

Radio theranostics in paragangliomas and pheochromocytomas.

This continuing education aims to present in a clear and easy-to-understand manner the biology of paragangliomas and pheochromocytomas (PPGLs), the functional imaging studies available for their diagnosis and therapeutic planning, the requirements necessary to administer radioligand therapy (RLT) and the characteristics of these treatments (inclusion criteria, administration protocols, adverse effects and future perspectives). In this pathology we have two RLT options: [131I]MIBG and [177Lu]Lu-DOTA-TATE. The indication for treatment is determined by the expression of its therapeutic target in functional imaging studies, allowing precision and personalized medicine. Although most of the results we have for both treatments have as origin small retrospective series, RLT is presented as a safe and well-tolerated therapeutic option in PPGLs with slow-moderate progression or with uncontrollable symptoms, obtaining high disease control rates.

Same-day comparative protocol PET/CT-PET/MRI [68 Ga]Ga-DOTA-TOC in paragangliomas and pheochromocytomas: an approach to personalized medicine.

BACKGROUND: PET/MRI is an emerging imaging modality which enables the evaluation and quantification of biochemical processes in tissues, complemented with accurate anatomical information and low radiation exposure. In the framework of theragnosis, PET/MRI is of special interest due to its ability to delineate small lesions, adequately quantify them, and therefore to plan targeted therapies. The aim of this study was to validate the diagnostic performance of [68 Ga]Ga-DOTA-TOC PET/MRI compared to PET/CT in advanced disease paragangliomas and pheochromocytomas (PGGLs) to assess in which clinical settings, PET/MRI may have a greater diagnostic yield. METHODS: We performed a same-day protocol with consecutive acquisition of a PET/CT and a PET/MRI after a single [68 Ga]Ga-DOTA-TOC injection in 25 patients. Intermodality agreement, Krenning Score (KS), SUVmax (Standard Uptake Value), target-to-liver-ratio (TLR), clinical setting, location, and size were assessed. RESULTS: The diagnostic accuracy with PET/MRI increased by 14.6% compared to PET/CT especially in bone and liver locations (mean size of new lesions was 3.73 mm). PET/MRI revealed a higher overall lesion uptake than PET/CT (TLR 4.12 vs 2.44) and implied an upward elevation of the KS in up to 60% of patients. The KS changed in 30.4% of the evaluated lesions (mean size 11.89 mm), in 18.4% of the lesions it increased from KS 2 on PET/CT to a KS ≥ 3 on PET/MRI and 24.96% of the lesions per patient with multifocal disease displayed a KS ≥ 3 on PET/MR, that were not detected or showed lower KS on PET/CT. In 12% of patients, PET/MRI modified clinical management. CONCLUSIONS: PET/MRI showed minor advantages over conventional PET/CT in the detection of new lesions but increased the intensity of SSRs expression in a significant number of them, opening the door to select which patients and clinical settings can benefit from performing PET/MRI.

The sentinel node with technetium-99m for prostate cancer. A safe and mature new gold standard?

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 99mTcnanocolloid. METHODS: We conducted a prospective study between January 2013 and May 2020. In the first 74 patients, 99mTc-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.

Response to targeted radionuclide therapy with [131I]MIBG AND [177Lu]Lu-DOTA-TATE according to adrenal vs. extra-adrenal primary location in metastatic paragangliomas and pheochromocytomas: A systematic review.

Purpose: Targeted radionuclide therapy (TRT) with [131I]MIBG and [177Lu]Lu-DOTA-TATE is an alternative treatment to the classic schemes in slow progressive metastatic/inoperable paraganglioma (PGL) and pheochromocytoma (PHEO). There is no consensus on which treatment to administer and/or the best sequence in patients who are candidates for both therapies. To clarify these questions, this systematic review assesses the prognostic value of [131I]MIBG and [177Lu]Lu-DOTA-TATE (PRRT-Lu) treatments in terms of progression-free survival (PFS) both globally and considering the primary location. Methods: This review was developed according to the PRISMA Statement with 27 final studies (608 patients). Patient characteristics, treatment procedure, and follow-up criteria were evaluated. In addition, a Bayesian linear regression model weighted according to its sample size and an alternative model, which also included an interaction between the treatment and the proportion of PHEOs, were carried out, adjusted by a Student's t distribution. Results: In linear regression models, [131I]MIBG overall PFS was, on average, 10 months lower when compared with PRRT-Lu. When considering the interaction between treatment responses and the proportion of PHEOs, PRRT-Lu showed remarkably better results in adrenal location. The PFS of PRRT-Lu was longer when the ratio of PHEOs increased, with a decrease in [131I]MIBG PFS by 1.9 months for each 10% increase in the proportion of PHEOs in the sample. Conclusion: Methodology, procedure, and PFS from the different studies are quite heterogeneous. PRRT-Lu showed better results globally and specifically in PHEOs. This fact opens the window to prospective trials comparing or sequencing [131I]MIBG and PRRT-Lu.

[177Lu]Lu-DOTA-TATE and [131I]MIBG Phenotypic Imaging-Based Therapy in Metastatic/Inoperable Pheochromocytomas and Paragangliomas: Comparative Results in a Single Center.

Purpose: The aim of the study is to assess phenotypic imaging patterns and the response to treatment with [177Lu]Lu-DOTA-TATE and/or [131I]MIBG in paragangliomas (PGLs) and pheochromocytomas (PHEOs), globally and according to the primary location. Methods: This is a 17-patient retrospective observational study, with 9 cases treated with [177Lu]Lu-DOTA-TATE and 8 with [131I]MIBG (37 total treatments). Functional imaging scans and treatment responses were studied in order to choose the best therapeutic option and to define the progression-free survival (PFS) and disease control rate (DCR) according to treatment modality and primary location. Results: All patients were studied with phenotypic nuclear medicine images. Twelve of 17 patients were tested with both [123I]MIBG and somatostatin receptor images, and 6/12 showed appropriate expression of both targets to treatment in the phenotypic images. The rest of the patients were tested with one of the image modalities or only showed suitable uptake of a single radiotracer and were treated with the corresponding therapeutic option. [177Lu]Lu-DOTA-TATE PFS was 29 months with a DCR of 88.8%. [131I]MIBG PFS was 18.5 months with a 62.5% DCR. According to the primary location, the best PFS was in PHEOs treated with [177Lu]Lu-DOTA-TATE. Although the series are small due to the low disease prevalence and do not allow to yield statistically significant differences, this first study comparing [177Lu]Lu-DOTA-TATE and [131I]MIBG displays a trend to an overall longer PFS with [177Lu]Lu-DOTA-TATE, especially in the adrenal primary location. When both radionuclide targets are expressed, the patients' comorbidity and treatment effectiveness should be valued together with the intensity uptake in the phenotypic image in order to choose the best therapeutic option. These preliminary retrospective results reinforce the need for a prospective, multicentric trial to be confirmed.

The Role of Imaging Studies in Favor of Possible Cerebellar Multiple System Atrophy: A Case Study.

ABSTRACT: We report a 64-year-old woman whose history started with urinary incontinence and neurological symptoms (cognitive impairment, dysarthria, and gait difficulties). The 18F-FDG PET/CT showed hypometabolism of the whole cerebellum. Then 6 months later, she developed tremor, postural instability, and ataxia, so she was hospitalized to complete study. Blood tests (antibodies, vitamin B12, copper, genetic test of spinocerebellar ataxia) did not have alterations, but imaging studies, along with clinical symptoms, provide the diagnosis of possible multiple system atrophy.

[Sentinel lymph node selective biopsy in prostate cancer.] / Ganglio centinela en cáncer de próstata.

OBJECTIVE: To validate the sentinel lymph node selective biopsy (SLNSB) in the staging of Prostate Cancer with Briganti Index > 5 by comparison with extended lymphadenectomy (ePLND) in a prospective longitudinal study. METHODS: SLNSB has been performed in 84 patients, the first 70 by injection of nanocoloids marked with Tc99m and preoperative SPECT-CT, and in the last 14 with mixed radiotracer (99mTc + ICG). After laparoscop ic removal of sentinel nodes all patients underwent an ePLND. RESULTS: SPECT-CT showed radiotracer deposits outside the territory of the ePLND in 76% of patients and laparoscopic gamma probe in 57%. The median number of sentinel nodes removed was 5.2 with a total average number of lymph nodes removed of 22. In all cases with metastatic nodes (28% in the series) there was at least one positive sentinel node but metastatic sentinel nodes outside of the territory of the ePLND were found in 6/24 patients (25%). The sensitivity, specificity, PPV and NPV of 99mTc were 100%, 96.07%, 90.47% and 100%, respectively. In 5 out of 14 patients with mixed radiotracer, lymph node involvement was detected. In all of them there was at least one sentinel node affected with 99mTc, and only 3 showed fluorescence with 100% sensitivity and 100% NPV for 99mTc and 60% sensitivity and 77.77% NPV for ICG. CONCLUSION: The SLNSB with 99mTc has a high sensitivity and a VPN of 100%, increasing the identification of lymphatic metastases outside the territory of the ePLND. Fluorescence can facilitate the visualization of the sentinel nodes when they have been previously located by the SPECT-CT, although the sensitivity and the NPV of the ICG are lower than that of the 99mTc.

OBJETIVO: Validar la biopsia selectiva de ganglio centinela (BSGC) en la estadificación del Cáncer de Próstata con Indice de Briganti > 5 mediante comparación con la linfadenectomía extendida (LFDe) en un estudio prospectivo longitudinal.MÉTODOS: Se ha realizado BSGC a 84 pacientes, los 70 primeros mediante inyección de nanocoloides marcados con Tc99m y SPECT-TC preoperatoria, y en los 14 últimos con radiotrazador mixto (Tc99m + ICG). A todos los pacientes tras la extracción laparoscópica de los ganglios centinelas se les realizó una LFDe. RESULTADOS: La SPECT-TC mostró depósitos del radiotrazador fuera del territorio de la LFDe en el 76% de los pacientes y la gammasonda laparoscópica en el 57%.La media de ganglios centinelas extraídos fue 5,2 con una media total de ganglios linfáticos extraídos de 22. En todos los casos con ganglios metastáticos (28% de la serie) hubo, al menos, un ganglio centinela positivo, encontrando ganglios centinela metastásicos fuera del territorio de la LFDe en 6/24 pacientes (25%). La sensibilidad, especificidad, VPP y VPN del Tc99m fue del 100%, 96,07%, 90,47% y 100%, respectivamente. En 5 de los 14 pacientes con radiotrazador mixto se detectó afectación ganglionar. En todos ellos hubo como mínimo un ganglio centinela afecto con Tc99m y sólo 3 mostraron fluorescencia, con sensibilidad del 100% y VPN del 100% para el Tc99m y sensibilidad del 60% y VPN del 77,77% para el ICG.CONCLUSIÓN: La BSGC con Tc99m tiene una alta sensibilidad y un VPN del 100%, aumentando la identificación de metástasis linfáticas fuera del territorio de la LFDe. La fluorescencia puede facilitar la visualización de los centinelas cuando se tiene una localización previa de los mismos con el SPECT-TAC, aunque la sensibilidad y el VPN del ICG es inferior al del Tc99m.

Ganglio centinela en cáncer de próstata / Sentinel lymph node selective biopsy in prostate cancer

Objetivo: Validar la biopsia selectiva de ganglio centinela (BSGC) en la estadificación del Cáncer de Próstata con Indice de Briganti > 5 mediante comparación con la linfadenectomía extendida (LFDe) en un estudio prospectivo longitudinal. Métodos: Se ha realizado BSGC a 84 pacientes, los 70 primeros mediante inyección de nanocoloides marcados con Tc99m y SPECT-TC preoperatoria, y en los 14 últimos con radiotrazador mixto (Tc99m + ICG). A todos los pacientes tras la extracción laparoscópica de los ganglios centinelas se les realizó una LFDe. Resultados: La SPECT-TC mostró depósitos del radiotrazador fuera del territorio de la LFDe en el 76% de los pacientes y la gammasonda laparoscópica en el 57%.La media de ganglios centinelas extraídos fue 5,2 con una media total de ganglios linfáticos extraídos de 22. En todos los casos con ganglios metastáticos (28% de la serie) hubo, al menos, un ganglio centinela positivo, encontrando ganglios centinela metastásicos fuera del territorio de la LFDe en 6/24 pacientes (25%). La sensibilidad, especificidad, VPP y VPN del Tc99m fue del 100%, 96,07%, 90,47% y 100%, respectivamente. En 5 de los 14 pacientes con radiotrazador mixto se detectó afectación ganglionar. En todos ellos hubo como mínimo un ganglio centinela afecto con Tc99m y sólo 3 mostraron fluorescencia, con sensibilidad del 100% y VPN del 100% para el Tc99m y sensibilidad del 60% y VPN del 77,77% para el ICG. Conclusión: La BSGC con Tc99m tiene una alta sensibilidad y un VPN del 100%, aumentando la identificación de metástasis linfáticas fuera del territorio de la LFDe. La fluorescencia puede facilitar la visualización de los centinelas cuando se tiene una localización previa de los mismos con el SPECT-TAC, aunque la sensibilidad y el VPN del ICG es inferior al del Tc99m

Objective: To validate the sentinel lymph node selective biopsy (SLNSB) in the staging of Prostate Cancer with Briganti Index > 5 by comparison with extended lymphadenectomy (ePLND) in a prospective longitudinal study. Methods: SLNSB has been performed in 84 patients, the first 70 by injection of nanocoloids marked with Tc99m and preoperative SPECT-CT, and in the last 14 with mixed radiotracer (99mTc + ICG). After laparoscop ic removal of sentinel nodes all patients underwent an ePLND. Results: SPECT-CT showed radiotracer deposits outside the territory of the ePLND in 76% of patients and laparoscopic gamma probe in 57%. The median number of sentinel nodes removed was 5.2 with a total average number of lymph nodes removed of 22. In all cases with metastatic nodes (28% in the series) there was at least one positive sentinel node but metastatic sentinel nodes outside of the territory of the ePLND were found in 6/24 patients (25%). The sensitivity, specificity, PPV and NPV of 99mTc were 100%, 96.07%, 90.47% and 100%, respectively. In 5 out of 14 patients with mixed radiotracer, lymph node involvement was detected. In all of them there was at least one sentinel node affected with 99mTc, and only 3 showed fluorescence with 100% sensitivity and 100% NPV for 99mTc and 60% sensitivity and 77.77% NPV for ICG. Conclusion: The SLNSB with 99mTc has a high sensitivity and a VPN of 100%, increasing the identification of lymphatic metastases outside the territory of the ePLND. Fluorescence can facilitate the visualization of the sentinel nodes when they have been previously located by the SPECT-CT, although the sensitivity and the NPV of the ICG are lower than that of the 99mTc

Pan-Costochondritis Caused by Aspergillus Diagnosed by 18F-FDG PET/CT.

Thoracic pain is an entity that can be difficult to diagnose etiologically. Once the cardiac origin has been ruled out, the rheumatologic, neoplastic, and infectious causes have to be taken into account. We present the case of a patient with atypical chest pain after triple-bypass surgery in whom F-FDG PET/CT scan showed an important uptake of the radiopharmaceutical in costal cartilages, in relation to pan-costochondritis due to Aspergillus.