Faculty Bibliography

OBJECTIVE:Indeterminate lesions on prostate-specific membrane antigen (PSMA)-PET are challenging to address. We aimed to develop, implement, and evaluate a multidisciplinary consensus algorithm that integrates existing interpretation systems with multimodality imaging and clinicopathological information for interpreting indeterminate bone and lymph node lesions on PSMA-PET. MATERIALS AND METHODS/METHODS:This was a retrospective single-center study on a prospectively implemented algorithm. We included all consecutive prostate cancer patients whose PSMA-PET findings for indeterminate bone lesions or lymph nodes were discussed at a multidisciplinary tumor board (MDT) in 2024-2025. An algorithm determining the level of suspicion for metastasis was developed in a multidisciplinary fashion, incorporating lesion location, conventional imaging features, PSMA-PET characteristics, and clinicopathological information. The application of the algorithm and outcomes were documented, compared against a composite reference standard. Comparisons were made with PSMA-RADS and PROMISE V2 PSMA-expression scores. RESULTS:81 patients (median age 68, interquartile range 64-75) were included. Algorithm results were benign (48.1% [39/81]), equivocal (4.9% [4/81]), metastasis (40.7% [33/81]), and mixed (benign and metastatic lesions, 6.2% [5/81]). The algorithm was correct in 94.1% (64 of 68 patients with a sufficient reference standard). The algorithm was discordant with PSMA-RADS in 54.3% (44/81) and with PROMISE V2 PSMA-expression score in 71.6% (58/81). The frequency of equivocal lesions was lower using the algorithm (4.9% [4/81]) compared with PSMA-RADS (53.1% [43/81]) and PSMA-expression score (64.2% [52/81]). CONCLUSION/CONCLUSIONS:A multidisciplinary consensus algorithm for interpreting indeterminate bone lesions and lymph nodes on PSMA-PET was developed and implemented. Integrating clinicopathological information and multimodality imaging in an MDT setting reduced equivocal interpretations. KEY POINTS/CONCLUSIONS:Question While prostate-specific membrane antigen (PSMA)-PET has become essential in the management of prostate cancer, indeterminate bone lesions and lymph nodes remain challenging to address. Findings A multidisciplinary algorithm for interpreting indeterminate bone lesions and lymph nodes on PSMA-PET, incorporating clinicopathological information and multimodality imaging, reduced the frequency of equivocal interpretations. Clinical relevance An algorithm for interpreting indeterminate bone lesions and lymph nodes on PSMA-PET, incorporating clinicopathological information and multimodality imaging in a multidisciplinary tumor board setting, decreases the frequency of equivocal interpretations and can potentially help management decisions.

OBJECTIVE:To develop a tool for the clinical hybrid imaging workflow which combines morphologic and functional measurements. And to quantify the number of clicks saved per positron emission tomography/computed tomography (PET/CT) interpretation. METHODS:A tool was developed where a volume of interest (VOI) is automatically created around line distance measurements. VOI statistics for both PET and CT component, and line distances are generated and displayed. Usage data for the first two months after introduction of the tool was analyzed. RESULTS:Eleven radiologists and nuclear medicine physicians used the tool in 364 PET/CTs. In 19% of examinations, the novel tool was the only tool that needed to be used. The novel combined tool was used 1001 times, whereas the traditional spherical VOI had been placed 1131 times. The usage ratio of new to traditional tool differed significantly between examinations with ≤ 6 annotations (ratio 1.0) versus > 6 annotations (ratio 0.63, p = 0.030). The average number of saved clicks per PET/CT was estimated at 16.5. CONCLUSION/CONCLUSIONS:A novel combined measurement tool for hybrid imaging was implemented and saved on average 16.5 clicks per examination. These improvements contribute to a smoother workflow and demonstrate the positive impact of thoughtful software design in medical practice.

PURPOSE/OBJECTIVE:To explore pragmatic approaches integrating MRI and PSMA-PET/CT for evaluating extraprostatic extension (EPE) of prostate cancer (PCa). METHODS:>12). Diagnostic performance was tested with receiver operating characteristic (ROC) curves and compared using DeLong and McNemar tests. RESULTS:>12 among which 87.5% (7/8) were corrected upgraded and had pathological EPE. CONCLUSION/CONCLUSIONS:Several pragmatic approaches were explored for integrating MRI and PSMA-PET/CT to assess EPE in PCa. Combining morphological information from MRI and PSMA expression on PET/CT demonstrated good diagnostic performance and may be a simple pragmatic integrated method that can be used.

OBJECTIVES/OBJECTIVE:Prostate-specific membrane antigen (PSMA)-PET/CT has become integral to management of prostate cancer; however, PSMA-avid rib lesions pose a diagnostic challenge. This study investigated clinicopathological and imaging findings that predict metastatic etiology of PSMA-avid rib lesions. MATERIALS AND METHODS/METHODS:), miPSMA score), CT features (sclerotic, lucent, fracture, no correlate), other sites of metastases, and primary tumor findings. A composite reference standard for rib lesion etiology (metastatic vs non-metastatic) based on histopathology, serial imaging, and clinical assessment was used. RESULTS:, miPSMA), more commonly involved multiple ribs, and were more often sclerotic (p < 0.01); lucency/fractures were only seen in benign lesions. CONCLUSION/CONCLUSIONS:Several imaging and clinicopathological factors differed between PSMA-avid metastatic and benign lesions. Isolated rib lesions without other sites of metastasis are almost always benign. Careful assessment of CT features can help diagnose benign lesions. KEY POINTS/CONCLUSIONS:Question While prostate-specific membrane antigen (PSMA)-PET/CT has become integral to the management of prostate cancer, PSMA-avid rib lesions pose a diagnostic challenge. Findings Approximately a quarter of patients who had PSMA-avid rib lesions were metastatic. However, only 2.1% of them had isolated rib metastasis (without PSMA-avid metastases elsewhere). Clinical relevance Isolated PSMA-avid rib lesions are almost always benign when there is no evidence of metastatic disease elsewhere. Scrutinizing CT features can help diagnose benign PSMA-avid lesions with greater certainty.

OBJECTIVES/OBJECTIVE:An increasing number of patients with prostate cancer (PCa) undergo assessment with magnetic resonance imaging (MRI) and prostate-specific membrane antigen positron emission tomography/computed tomography (PSMA-PET/CT). This offers comprehensive multimodality staging but can lead to discrepancies. The objective was to assess the rates and types of discordance between MRI and PSMA-PET/CT for primary PCa assessment. MATERIALS AND METHODS/METHODS:Consecutive men diagnosed with intermediate and high-risk PCa who underwent MRI and PSMA-PET/CT in 2021-2023 were retrospectively included. MRI and PSMA-PET/CT were interpreted using PI-RADS v2.1 and PRIMARY scores. Discordances between the two imaging modalities were categorized as "minor" (larger or additional lesion seen on one modality) or "major" (positive on only one modality or different index lesions between MRI and PSMA-PET/CT) and reconciled using radical prostatectomy or biopsy specimens. RESULTS:Three hundred and nine men (median age 69 years, interquartile range (IQR) 64-75) were included. Most had Gleason Grade Group ≥ 3 PCa (70.9% (219/309)). Median PSA was 9.0 ng/mL (IQR 5.6-13.6). MRI and PSMA-PET/CT were concordant in 157/309 (50.8%) and discordant in 152/309 (49.1%) patients; with 39/152 (25.7%) major and 113/152 (74.3%) minor discordances. Of 27 patients with lesions only seen on MRI, 85.2% (23/27) were clinically significant PCa (csPCa). Of 23 patients with lesions only seen on PSMA-PET/CT, 78.3% (18/23) were csPCa. Altogether, lesions seen on only one modality were csPCa in 80.0% (36/45). CONCLUSION/CONCLUSIONS:MRI and PSMA-PET/CT were discordant in half of patients for primary PCa evaluation, with major discrepancies seen in roughly one out of eight patients. KEY POINTS/CONCLUSIONS:Question While both MRI and PSMA-PET/CT can be used for primary tumor assessment, the discordances between them are not well established. Findings MRI and PSMA-PET/CT were discordant in about half of the patients. Most prostate lesions seen on only one modality were significant cancer. Clinical relevance MRI and PSMA-PET/CT are often discordant for assessing the primary prostate tumor. Using both modalities for primary prostate tumor evaluation can provide complementary information that may substantially impact treatment planning.

Imaging is used for lymphoma detection, Ann Arbor/Lugano staging, and treatment response assessment. [¹⁸F]FDG PET/CT should be used for most lymphomas, including Hodgkin lymphoma, aggressive/high-grade Non-Hodgkin lymphomas (NHL) such as diffuse large B-cell lymphoma, and many indolent/low-grade NHLs such as follicular lymphoma. Apart from these routinely FDG-avid lymphomas, some indolent NHLs, such as marginal zone lymphoma, are variably FDG-avid; here, [¹⁸F]FDG PET/CT is an alternative to contrast-enhanced CT at baseline and may be used for treatment response assessment if the lymphoma was FDG-avid at baseline. Only small lymphocytic lymphoma/chronic lymphocytic leukemia (SLL/CLL) should exclusively undergo CT at baseline and follow-up unless transformation to high-grade lymphoma is suspected. While [¹⁸F]FDG PET/CT is sufficient to rule out bone marrow involvement in Hodgkin lymphoma, biopsy may be needed in other lymphomas. The 5-point (Deauville) score for [¹⁸F]FDG PET that uses the liver and blood pool uptake as references should be used to assess treatment response in all FDG-avid lymphomas; post-treatment FDG uptake ≤ liver uptake is considered complete response. In all other lymphomas, CT should be used to determine changes in lesion size; for complete response, resolution of all extranodal manifestations, and for lymph nodes, long-axis decrease to ≤ 1.5 cm are required. KEY POINTS: [¹⁸F]FDG-PET/CT and contrast-enhanced CT are used to stage lymphoma depending on type. Imaging is required for staging, and biopsies may be required to rule out bone marrow involvement. For treatment response assessment, the 5-PS (Deauville) score should be used; in a few indolent types, CT is used to determine changes in lesion size.

Liquid biopsy helps detect cells and cell-derived metabolites, proteins, nucleic acids, and vesicles that are shed into body fluids by tumors. This diagnostic test requires only approximately 10 mL of blood or urine. It has received considerable attention as a minimally invasive tool for whole-body tumor interrogation for use in patients with cancer. It poses an attractive and potentially cost-effective alternative to invasive tissue sampling through tissue biopsies, especially serial assessments, such as for treatment response evaluation and mutations that occur during cancer treatment. Cell-free and circulating tumor DNA are the most frequently tested liquid biopsy analytes, and have shown promise for cancer screening, assessment of residual disease after treatment, and clinical outcome prediction and prognostication. Whereas liquid biopsy is less sensitive than imaging in early tumor stages, it is more specific and may help detect treatment response earlier than the Response Evaluation Criteria in Solid Tumors, or RECIST. Aimed primarily at radiologists, this review article provides an update on recent developments in the use of liquid biopsy, including findings from landmark clinical trials and U.S. regulatory approvals as companion diagnostic tests for clinical use, particularly in four malignancies: lymphoma, breast cancer, prostate cancer, and melanoma. Finally, current challenges for the clinical implementation of liquid biopsy are discussed.

Tumor-agnostic precision medicine (PM) strategies promise to support treatment decisions in relapsed/refractory blood cancer patients. Genomic-based PM (gPM) and drug screening-based functional PM (fPM) currently represent the most prominent PM methodologies. In this study, we report the feasibility analysis of the first 55 patients enrolled in the multicentric, randomized controlled EXALT-2 trial (NCT04470947) comparing treatment recommendations of gPM, fPM, and physicians' choice (PC) head to head. In 54 patients (98%), the diagnostic workflow was successfully implemented, resulting in treatment recommendations for 42 patients (76%), of whom 29 (69%) received the suggested individualized treatments. Actionable targets were identified in 65% by gPM and 80% by fPM (64% microscopy-based, 86% flow cytometry-based fPM). The median time to report was shorter for fPM than for gPM testing. The two strategies revealed overlapping drug targets in 60% of cases. Both, gPM and fPM can efficiently be integrated into the clinical routine to guide therapy decisions for the majority of patients.