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Introduction: Primary prostate cancer (PCa) can be visualized on prostate-specific membrane antigen positron emission tomography (PSMA-PET) with high accuracy. However, intraprostatic lesions may be missed by visual PSMA-PET interpretation. In this work, we quantified and characterized the intraprostatic lesions which have been missed by visual PSMA-PET image interpretation. In addition, we investigated whether PSMA-PET-derived radiomics features (RFs) could detect these lesions. Methodology: This study consists of two cohorts of primary PCa patients: a prospective training cohort (n = 20) and an external validation cohort (n = 52). All patients underwent 68Ga-PSMA-11 PET/CT and histology sections were obtained after surgery. PCa lesions missed by visual PET image interpretation were counted and their International Society of Urological Pathology score (ISUP) was obtained. Finally, 154 RFs were derived from the PET images and the discriminative power to differentiate between prostates with or without visually undetectable lesions was assessed and areas under the receiver-operating curve (ROC-AUC) as well as sensitivities/specificities were calculated. Results: In the training cohort, visual PET image interpretation missed 134 tumor lesions in 60% (12/20) of the patients, and of these patients, 75% had clinically significant (ISUP > 1) PCa. The median diameter of the missed lesions was 2.2 mm (range: 1–6). Standard clinical parameters like the NCCN risk group were equally distributed between patients with and without visually missed lesions (p < 0.05). Two RFs (local binary pattern (LBP) size-zone non-uniformality normalized and LBP small-area emphasis) were found to perform excellently in visually unknown PCa detection (Mann-Whitney U: p < 0.01, ROC-AUC: ≥ 0.93). In the validation cohort, PCa was missed in 50% (26/52) of the patients and 77% of these patients possessed clinically significant PCa. The sensitivities of both RFs in the validation cohort were ≥ 0.8. Conclusion: Visual PSMA-PET image interpretation may miss small but clinically significant PCa in a relevant number of patients and RFs can be implemented to uncover them. This could be used for guiding personalized treatments. [ABSTRACT FROM AUTHOR]

Purpose: Readers need to be informed about potential pitfalls of [68Ga]Ga-PSMA-11 PET interpretation. Methods: Here we report [68Ga]Ga-PSMA-11 PET findings discordant with the histopathology/composite reference standard in a recently published prospective trial on 635 patients with biochemically recurrent prostate cancer. Results: Consensus reads were false positive in 20 regions of 17/217 (8%) patients with lesion validation. Majority of the false positive interpretations (13 of 20, 65%) occurred in the context of suspected prostate (bed) relapse (T) after radiotherapy (n = 11); other false positive findings were noted for prostate bed post prostatectomy (T, n = 2), pelvic nodes (N, n = 2), or extra pelvic lesions (M, n = 5). Major sources of false positive findings were PSMA-expressing residual adenocarcinoma with marked post-radiotherapy treatment effect. False negative interpretation occurred in 8 regions of 6/79 (8%) patients with histopathology validation, including prostate (bed) (n = 5), pelvic nodes (n = 1), and extra pelvic lesions (n = 2). Lesions were missed mostly due to small metastases or adjacent bladder/urine uptake. Conclusion: [68Ga]Ga-PSMA-11 PET at biochemical recurrence resulted in less than 10% false positive interpretations. Post-radiotherapy prostate uptake was a major source of [68Ga]Ga-PSMA-11 PET false positivity. In few cases, PET correctly detects residual PSMA expression post-radiotherapy, originating however from treated, benign tissue or potentially indolent tumor remnants. Trial registration number: ClinicalTrials.gov Identifiers: NCT02940262 and NCT03353740. [ABSTRACT FROM AUTHOR]

Purpose: To evaluate the biodistribution of [18F]Florastamin, a novel 18F-labelled positron emission tomography (PET) tracer for prostate-specific membrane antigen (PSMA) for the diagnosis of prostate cancer. Methods: PET was performed for five healthy controls and 10 patients with prostate cancer at 0, 10, 30, 70, and 120 mins after injecting 370 MBq of [18F]Florastamin. The maximum standardised uptake value (SUVmax) was evaluated in the primary tumour. The mean SUVmax (SUVmean) was evaluated in normal organs. Furthermore, the residence time was evaluated by assessing radioactivity in each organ. The internal radiation dosimetry was calculated using the OLINDA/EXM software. Results: The SUVmax in primary tumours increased with time. A favourable tumour to background ratio was also observed over time. Multiple lymph nodes and bone metastases were also evaluated and showed a similar pattern to SUVmax in the primary tumour. In one patient, a tiny lymph node metastasis was identified using [18F]Florastamin PET, which was not observed using other modalities, and was histologically confirmed. The highest absorbed dose was observed in the kidney (0.062 ± 0.015 mGy/MBq), followed by the bladder (0.032 ± 0.013 mGy/MBq), liver (0.022 ± 0.006 mGy/MBq), and salivary gland (0.018 ± 0.006 mGy/MBq). The effective dose with a 370 MBq injection of [18F]Florastamin was 1.81 mSv. No adverse events related to [18F]Florastamin were reported. Conclusion: We identified a novel PSMA-targeted PET ligand, [18F]Florastamin, for imaging prostate cancer. [18F]Florastamin showed a high SUVmax and relatively high tumour to background ratio in both primary tumour and metastatic lesions, which suggests its high sensitivity to detect tumours without any adverse events. Trial registration: KCT0003924 registered at https://cris.nih.go.kr/. [ABSTRACT FROM AUTHOR]

Purpose: We analysed quantitative biomarkers derived from both baseline whole-body imaging and blood serum to identify prognostic markers in patients treated within the lutetium-177 prostate-specific membrane antigen (LuPSMA) phase 2 trial. Methods: PET image analysis was carried out using whole-body segmentation quantifying molecular tumour volume (SUV > 3 threshold for PSMA, SUV > liver+2sd for fluorodeoxyglucose (FDG) including SUVmax and SUVmean. For baseline bone scans, EXINI bone scan index (BSI) was used to calculate the percentage of involved bone. Baseline alkaline phosphatase (ALP), lactate dehydrogenase (LDH), prostate specific antigen (PSA) and PSA doubling time were also used in this analysis. We used univariate cox regression analysis and log-rank comparison with optimised cut-offs to find suitable biomarkers prognostic of overall survival from time of enrolment. Results: This analysis identified FDG-positive tumour volume (FDGvol; HR 2.6; 95% CI, 1.4–4.8), mean intensity of PSMA-avid tumour uptake (PSMAmean; HR 0.89; 95% CI, 0.8–0.98), bone scan index (BSI; HR 2.3; 95% CI, 1.2–4.4), ALP (HR 1.1; 95% CI, 1–1.2) and LDH (HR 1.2; 95% CI, 1–1.5) as biomarkers prognostic of overall survival. Conclusions: In addition to established biomarkers, both FDG and PSMA PET/CT parameters have prognostic significance for survival in men undergoing LuPSMA therapy. [ABSTRACT FROM AUTHOR]

Introduction: A new therapeutic option for metastatic castration–resistant prostate cancer (mCRPC) of heavily pre-treated patients lies in 177Lu-PSMA-617 radioligand therapy. Methods: On the basis of PSMA-targeted 68Ga-PSMA-11 PET/CT, 32 consecutive mCRPC patients were selected for 177Lu-PSMA-617 therapy (6 GBq/cycle, 2 to 6 cycles, 6–10 weeks apart) and followed until death. Post-therapy whole-body (WB) dosimetry and 68Ga-PSMA-11 PET/CT data were compared and related to progression free and overall survival. Results: 177Lu-PSMA-617 dosimetry after the first cycle indicated high tumor doses for skeletal (4.01 ± 2.64; range 1.10–13.00 Gy/GBq), lymph node (3.12 ± 2.07; range 0.70–8.70 Gy/GBq), and liver (2.97 ± 1.38; range 0.76–5.00 Gy/GBq) metastases whereas the dose for tissues/organs was acceptable in all patients for an intention-to-treat activity of 24 GBq. Any PSA decrease after the first cycle was found in 23/32 (72%), after the second cycle in 22/32 (69%), after the third cycle in 16/28 (57%), and after the fourth cycle in 8/18 (44%) patients. Post-therapy 24 h WB scintigraphy showed decreased tumor-to-background ratios in 24/32 (75%) after the first therapy cycle, after the second cycle in 17/29 (59%), and after the third cycle in 13/21 (62%) patients. The median PFS was 7 months and the median OS 12 months. In the group of PSA responders (n = 22) the median OS was 17 months versus 11 months in the group of non-responders (n = 10), p < 0.05. Decreasing SUVmax values were found for parotid (15.93 ± 6.23 versus 12.33 ± 4.07) and submandibular glands (17.65 ± 7.34 versus 13.12 ± 4.62) following treatment, along with transient (n = 6) or permanent (n = 2) xerostomia in 8/32 (25%) patients. In 3/32 patients, nephrotoxicity changed from Grade 2 to 3, whereas neither Grade 4 nephrotoxicity nor hematotoxicity was found. In most patients a good agreement was observed for the visual interpretation of the tracer accumulation between 24 h WB and PET/CT scans. However, no significance could be calculated for baseline-absorbed tumor doses and SUVmax values of tumor lesions. 5/32 (16%) patients showed a mixed response pattern, which resulted in disease progression over time. Conclusion: Serial PSA measurements and post-therapy 24 h WB scintigraphy seems to allow a sufficiently accurate follow-up of 177Lu-PSMA-617-treated mCRPC patients whereas 68Ga-PSMA-11 PET/CT should be performed for patient selection and final response assessment. [ABSTRACT FROM AUTHOR]

Purpose: Dual-time point PET/CT scanning with [68Ga]Ga-PSMA-11 in the diagnosis of prostate cancer (PC) has been advanced as a method to increase detection of PC lesions, particularly at early stages of biochemical recurrence and as a potential means to aid the discrimination between benign and pathological prostate-specific membrane antigen (PSMA) uptake. However, the assumption that all PC lesions uniformly exhibit increasing tracer uptake at delayed imaging has not yet been investigated, which this present study aims to address. Methods: One hundred consecutive patients with biochemically recurrent PC who received standard and late [68Ga]Ga-PSMA-11 PET/CT (by local protocol at 1.5 h "standard" and 2.5 h p.i. "late") underwent retrospective evaluation. All lesions with a tracer uptake above local background were analysed with regard to their maximum standardised uptake values at standard and late images (SUVmax) and characterised according to their morphological characteristics. Results: Seventy-nine of 100 patients had PSMA-positive scans, in whom a total of 185 individual PSMA-positive lesions were identified. These were morphologically characterised as bone lesions (n = 48), solid organ lesions (n = 3), lymph node (LN) lesions (n = 78) and locally recurrent lesions in the prostatic fossa or seminal vesicles (n = 56). The relative uptake between standard and late imaging was considered; all lesions classified as local recurrence presented with increasing (86%) or stable patterns of tracer uptake (14%). In contrast, only 58% of bone lesions exhibited increasing tracer uptake, with 21% exhibiting a stable pattern and 21% exhibiting a decreasing tracer uptake at late imaging. Conclusion: A heterogeneous pattern of dynamic tracer uptake was observed, with a largely increasing pattern observed for locally recurrent lesions and lymph nodes and a significant proportion of bone lesions exhibiting decreasing tracer uptake. The results are of significance not only in the imaging and identification of PC lesions, but they also have implications for PSMA-directed ligand therapy. [ABSTRACT FROM AUTHOR]

Purpose: The present study is based on a retrospective analysis of Gallium-68 (68Ga)-labelled prostate-specific membrane antigen (68Ga-PSMA I&T) PET/CT performed in newly diagnosed, treatment-naïve prostate cancer (PCa) patients prior to definitive treatment. Methods: A total of 82 men were included in the study and were imaged with 68Ga-PSMA I&T PET/CT to assess the distribution of PSMA-avid disease for staging purposes (11 with low-risk, 32 with intermediate-risk, and 39 with high-risk PCa). Forty patients (20 with intermediate- and 20 with high-risk disease) underwent subsequent radical prostatectomy with extended pelvic lymph node dissection which allowed for correlation of imaging findings with histopathologic data. Results: PSMA-positive disease was detected in 83% of patients with 66/82 (80.5%) primary tumours being visualized. PSMA-avid lymph nodes were recorded in 17/82 patients (20.7%, 3 with intermediate-risk and 14 with high-risk PCa); distant disease was found in 14/82 subjects (17.1%, 2 with intermediate-risk and 12 with high-risk PCa). No extraprostatic disease was found in low-risk PCa. SUVmax of primary tumours showed a weak but significant correlation with serum PSA values (r = 0.51, p < 0.001) and Gleason scores (GSC; r = 0.35, p = 0.001), respectively. In correlation with histopathology, calculated per-region sensitivity, specificity, positive predictive value, negative predictive value, and accuracy for detection of lymph node metastases were 35.0%, 98.4%, 63.6%, 95.0%, and 93.0%, respectively. Conclusions: In patients with initial diagnosis of intermediate- and high-risk prostate cancer, 68Ga-PSMA I&T PET/CT emerges as a relevant staging procedure by identifying nodal and/or distant metastases. Due to the low prevalence of extraprostatic disease, its value seems to be limited in low-risk disease. [ABSTRACT FROM AUTHOR]

Aim: 68Ga-RM2 is a bombesin (BBN) analog that targets the gastrin releasing peptide receptors (GRPR) overexpressed in many cancer cells, including prostate cancer (PC). It has been reported to successfully detect primary and recurrent PC. Here, we describe the distribution and range of physiological uptake of 68Ga-RM2 in 95 patients with biochemically recurrent (BCR) PC. Materials and methods: Ninety-five participants had simultaneous PET/MRI for BCR PC and were prospectively enrolled in this study. Maximum standardized uptake value (SUVmax) and mean standardized uptake value (SUVmean) were measured in 24 normal anatomical structures for each participant. Three readers evaluated the images independently. Uptake in various normal tissues was classified into 4 different categories: no significant uptake if SUVmean was less than SUVmean of the aortic arch (AA); mild if SUVmean was less or equal to 2.5, but higher than SUVmean of the AA; moderate if SUVmean was higher than 2.5, but less or equal to 5; intense if SUVmean was higher than 5. Results: The most intense uptake was observed in the urinary bladder, due to excretion of the radiotracer. No significant uptake was seen in the brain, salivary glands, lungs, myocardium, skeleton, muscles, and fat. Liver, spleen, and adrenal glands had mostly no significant uptake; the gastrointestinal tract had intense physiological uptake, with pancreas being the organ with the highest SUVmax measurements (average SUVmax 64.91). Mild and moderate uptake was measured in the esophagus (average SUVmax 3.99), while the stomach wall, duodenum, and rectum had mild uptake (average SUVmax 2.49, 3.42, and 3.58, respectively). Conclusions: 68Ga-RM2 has been mostly evaluated for PC detection, but it can be used for other tumors overexpressing GRPR such as breast cancer. This atlas of normal biodistribution and SUV measurements in healthy tissues will help physicians distinguish between physiological vs. pathological uptake, as well as potentially assist with planning future studies using GRPR targeting radiopharmaceuticals. [ABSTRACT FROM AUTHOR]

Purpose: Diagnostic imaging modalities have moderate sensitivity for the identification of lymph node (LN) metastases in prostate cancer (PCa) patients. Mapping the lymphatic drainage from the prostate can help to identify the LNs directly draining from the tumour (sentinel nodes (SNs)); the LNs stated to have the highest chance of containing metastatic cancer cells. Although the lymphatic drainage may differ between segments within the prostate, the location of the primary tumour is not routinely taken into account during peripheral zone-aimed tracer administration. This study evaluates whether linking the SN procedure to the primary cancer deposits increases the identification accuracy of lymphatic metastases. Methods: Sixty-seven PCa patients, scheduled for robot-assisted laparoscopic prostatectomy (RALP) and extended lymph node dissection (ePLND) with subsequent SN biopsy, were included in this retrospective study. After injection of the hybrid tracer ICG-99mTc-nanocolloid in the prostate, SN mapping was performed based on lymphoscintigraphy and SPECT/CT. SNs were resected using a combination of radio- and fluorescence guidance. Pathology was used to determine the primary tumour location and metastatic spread. Fluorescence imaging of paraffin-embedded prostate tissue was used to determine the location of the tracer deposits in the prostate. This deposition was related to the primary tumour location, the lymphatic drainage pattern of the injected tracer, and the metastatic spread. Results: In total 265 radioactive LNs (211 SNs and 54 higher-echelon nodes in 64 patients; 4.3 LNs per patient; IQR: 2–6) were identified. In three patients (4%) preoperative imaging did not allow identification of SNs. Tumour-positive SN visualization within the pelvis was shown to be influenced by intraprostatic location of tracer administration. This could be concluded from (1) a clear correlation between lymphatic drainage to the right or left side of the body and tracer deposition on the right or left side of the prostate, (2) visualization of a higher number of LNs after dorsal tracer deposition compared with ventral tracer deposition, (3) different drainage patterns observed for tracer deposition into the base or apex of the prostate, and (4) the indication that intratumoural tracer deposition increases the chance of visualizing nodal metastases compared with extratumoural tracer deposition. Conclusions: The correlation between the location of the tracer deposits, the location of the primary tumour, and the visualization of the (tumour-positive) SNs indicated that placement of tracer deposits is of influence on the visualized lymphatic drainage pattern. This suggests that tracer injection near or into the primary tumour site is beneficial for the identification of metastatic spread. [ABSTRACT FROM AUTHOR]

This article is part of the Topical Collection on Oncology - Genitourinary A 71-year-old man with advanced castration-resistant prostate cancer was referred to our department for evaluation of prostate-specific membrane antigen (PSMA)-directed radioligand therapy (RLT). In order to rule out PSMA-negative disease, SP 18 sp F-FDG-PET CT (Figure c) was additionally performed [[1]], demonstrating two FDG-avid liver lesions highly suspicious for hepatic metastases without corresponding SP 18 sp F-PSMA-1007 uptake (Figure c red arrows; axial slices: Figure e and f). [Extracted from the article]

Purpose: The purpose of this study was to evaluate the efficacy and safety of a novel theranostic agent, Lu-DKFZ-PSMA-617 therapy in metastatic castration resistant prostate cancer (mCRPC). Methods: Thirty-one mCRPC patients with progressive disease despite second-line hormonal therapy and/or docetaxel chemotherapy were recruited for the study. All patients underwent diagnosticGa-PSMA-HBED-CCPET/CT, prior to inclusion for therapy. Included patients then underwent quarterly Lu-DKFZ-PSMA-617 therapy. Hematological, kidney function, liver function tests, and serum PSA levels were recorded before and after therapy at 2 weeks, 4 weeks, and 3 month intervals. Biochemical response was assessed with trend in serum PSA levels. Metabolic response was assessed by PERCIST 1 criteria. Clinical response was assessed by visual analogue score (VASmax) analgesic score (AS), Karanofsky performance status (KPS), and ttoxicity and response criteria of the Eastern Cooperative Oncology Group (ECOG) criteria. Results: The mean age of patients was 65.93 ± 9.77 years (range: 38-81 years). The mean activity administered in the 31 patients was 5069 ± 1845 MBq ranging from one to four cycles. There was a decline in the mean serum PSA levels from the baseline (baseline: 275 ng/mL, post 1st cycle therapy: 141.75 ng/mL). Based on biochemical response criteria 2/31, 20/31, 3/31, and 6/31 had complete response (CR), partial response(PR), stable disease (SD), and progressive disease (PD), respectively. Metabolic response revealed 2/6 patients with CR, and the remaining 3/6 patients with PR and 1/6 patients with SD. The mean VASmax score decreased from 7.5 to 3. The mean analgesic score decreased from 2.5 to 1.8 after therapy. The mean KPS score improved from 50.32 to 65.42 after therapies. The mean ECOG performance status improved from 2.54 to 1.78 after therapy. Two patients experienced grade I and grade II hemoglobin toxicity each. None of the patients experienced nephrotoxicity or hepatotoxicity. Conclusion: Lu-DKFZ-PSMA-617 radionuclide therapy is a safe and effective approach in the treatment of mCRPC patients. [ABSTRACT FROM AUTHOR]

Purpose: Prostate-specific membrane antigen (PSMA) is expressed ubiquitously on the membrane of most prostate tumors and its metastasis. While PET/CT using C-choline was considered as the gold standard in the staging of prostate cancer, PET with radiolabelled PSMA ligands was introduced into the clinic in recent years. Our aim was to compare the PSMA ligand Ga-PSMA-11 with C-choline in patients with primary and recurrent prostate cancer. Methods: 123 patients underwent a whole-body PET/CT examination using Ga-PSMA-11 and C-choline. Suspicious lesions were evaluated visually and semiquantitatively (SUVavg). Out of these, 103 suffered from a confirmed biochemical relapse after prostatectomy and/or radiotherapy (mean PSA level of 4.5 ng/ml), while 20 patients underwent primary staging. Results: In 67 patients with biochemical relapse, we detected 458 lymph nodes suspicious for metastasis. PET using Ga-PSMA-11 showed a significantly higher uptake and detection rate than C-choline PET. Also Ga-PSMA-11 PET identified significantly more patients with suspicious lymph nodes as well as affected lymph nodes regions especially at low PSA levels. Bone lesions suspicious for prostate cancer metastasis were revealed in 36 patients' biochemical relapse. Significantly more bone lesions were detected by Ga-PSMA-11, but only 3 patients had only PSMA-positive bone lesions. Nevertheless, we detected also 29 suspicious lymph nodes and 8 bone lesions, which were only positive as per C-choline PET. These findings led to crucial differences in the TNM classification and the identification of oligometastatic patients. In the patients who underwent initial staging, all primary tumors showed uptake of both tracers. Although significantly more suspicious lymph nodes and bone lesions were identified, only 2 patients presented with bone lesions only detected by Ga-PSMA-11 PET. Conclusion: Thus, PET using Ga-PSMA-11 showed a higher detection rate than C-choline PET for lymph nodes as well as bone lesions. However, we found lymph nodes and bone lesions which were not concordant applying both tracers. [ABSTRACT FROM AUTHOR]

Purpose: To evaluate the diagnostic potential of whole-body PET/CT using a Ga-labelled PSMA ligand in renal cell carcinoma (RCC). Methods: Six patients with histopathologically proven RCC underwent Ga-PSMA PET/CT. Each PET/CT scan was evaluated in relation to lesion count, location and dignity. SUVmax was measured in primary tumours and PET-positive metastases. Tumour-to-background SUVmax ratios (TBR) were calculated for primary RCCs in relation to the surrounding normal renal parenchyma. Metastasis-to-background SUVmax ratios (MBR) were calculated for PET-positive metastases in relation to gluteal muscle. Results: Five primary RCCs and 16 metastases were evaluated. The mean SUVmax of the primary RCCs was 9.9 ± 9.2 (range 1.7 - 27.2). Due to high uptake in the surrounding renal parenchyma, the mean TBR of the primary RCCs was only 0.2 ± 0.3 (range 0.02 - 0.7). Eight metastases showed focal Ga-PSMA uptake (SUVmax 9.9 ± 8.3, range 3.4 - 25.6). The mean MBR of these PET-positive metastases was 11.7 ± 0.2 (range 4.4 - 28.1). All PET-negative metastases were subcentimetre lung metastases. Conclusion: Ga-PSMA PET/CT appears to be a promising method for detecting RCC metastases. However, no additional diagnostic value in assessing the primary tumour was found. [ABSTRACT FROM AUTHOR]

Purpose: Since the introduction of positron emission tomography (PET) imaging with Ga-PSMA-HBED-CC (=Ga-DKFZ-PSMA-11), this method has been regarded as a significant step forward in the diagnosis of recurrent prostate cancer (PCa). However, published data exist for small patient cohorts only. The aim of this evaluation was to analyse the diagnostic value of Ga-PSMA-ligand PET/CT in a large cohort and the influence of several possibly interacting variables. Methods: We performed a retrospective analysis in 319 patients who underwent Ga-PSMA-ligand PET/CT from 2011 to 2014. Potential influences of several factors such as prostate-specific antigen (PSA) level and doubling time (DT), Gleason score (GSC), androgen deprivation therapy (ADT), age and amount of injected tracer were evaluated. Histological verification was performed in 42 patients after the Ga-PSMA-ligand PET/CT. Tracer uptake was measured in 901 representative tumour lesions. Results: In 82.8 % of the patients at least one lesion indicative of PCa was detected. Tumor-detection was positively associated with PSA level and ADT. GSC and PSA-DT were not associated with tumor-detection. The average maximum standardized uptake value (SUV) of tumour lesions was 13.3 ± 14.6 (0.7-122.5). Amongst lesions investigated by histology, 30 were false-negative in 4 different patients, and all other lesions ( n = 416) were true-positive or true-negative. A lesion-based analysis of sensitivity, specificity, negative predictive value (NPV) and positive predictive value (PPV) revealed values of 76.6 %, 100 %, 91.4 % and 100 %. A patient-based analysis revealed a sensitivity of 88.1 %. Of 116 patients available for follow-up, 50 received local therapy after Ga-PSMA-ligand PET/CT. Conclusion: Ga-PSMA-ligand PET/CT can detect recurrent PCa in a high number of patients. In addition, the radiotracer is highly specific for PCa. Tumour detection is positively associated with PSA and ADT. Ga-PSMA-ligand PET/CT can help delay systemic therapy of PCa. [ABSTRACT FROM AUTHOR]

Purpose: IgG4-related disease (IgG4-RD) is an increasingly recognized clinicopathological disorder with immune-mediated inflammatory lesions mimicking malignancies. A cohort study was prospectively designed to investigate the value of F-fluorodeoxyglucose (FDG) positron emission tomography/computed tomography (PET/CT) in characterizing IgG4-RD. Methods: Thirty-five patients diagnosed with IgG4-RD according to the consensus criteria were enrolled with informed consent. All patients underwent baseline F-FDG PET/CT evaluation. Among them, 29 patients underwent a second F-FDG PET/CT scan after 2 to 4 weeks of steroid-based therapy. Results: All 35 patients were found with F-FDG-avid hypermetabolic lesion(s); 97.1 % (34/35) of these patients showed multi-organ involvement. Among the 35 patients, 71.4 % (25/35) patients were found with more organ involvement on F-FDG PET/CT than conventional evaluations including physical examination, ultrasonography, and computed tomography (CT). F-FDG PET/CT demonstrated specific image characteristics and pattern of IgG4-RD, including diffusely elevated F-FDG uptake in the pancreas and salivary glands, patchy lesions in the retroperitoneal region and vascular wall, and multi-organ involvement that cannot be interpreted as metastasis. Comprehensive understanding of all involvement aided the biopsy-site selection in seven patients and the recanalization of ureteral obstruction in five patients. After 2 to 4 weeks of steroid-based therapy at 40 mg to 50 mg prednisone per day, 72.4 % (21/29) of the patients showed complete remission, whereas the others exhibited > 81.8 % decrease in F-FDG uptake. Conclusion: F-FDG PET/CT is a useful tool for assessing organ involvement, monitoring therapeutic response, and guiding interventional treatment of IgG4-RD. The image pattern is suggested to be updated into the consensus diagnostic criteria for IgG4-RD. [ABSTRACT FROM AUTHOR]

We investigated the usefulness of [ SP 68 sp Ga]Ga-DOTA-FAPI-04 PET/CT imaging in a case of prostate cancer with shoulder arthritis. However, in our case, the increase in the tracer uptake on [ SP 68 sp Ga]Ga-DOTA-FAPI-04 imaging was similar to that on [ SP 18 sp F]FDG imaging, indicating that [ SP 68 sp Ga]Ga-DOTA-FAPI-04 imaging may not be more tumour-specific than [ SP 18 sp F]FDG for prostate cancer. [Extracted from the article]

Purpose: Ga-labelled HBED-CC-PSMA is a highly promising tracer for imaging recurrent prostate cancer (PCa). The intention of this study was to evaluate the feasibility of PET/MRI with this tracer. Methods: Twenty patients underwent PET/CT 1 h after injection of the Ga-PSMA ligand followed by PET/MRI 3 h after injection. Data from the two investigations were first analysed separately and then compared with respect to tumour detection rate and radiotracer uptake in various tissues. To evaluate the quantification accuracy of the PET/MRI system, differences in SUVs between PET/CT and corresponding PET/MRI were compared with differences in SUVs between PET/CT 1 h and 3 h after injection in another patient cohort. This cohort was investigated using the same PET/CT system. Results: With PET/MRI, different diagnostic sequences, higher contrast of lesions and higher resolution of MRI enabled a subjectively easier evaluation of the images. In addition, four unclear findings on PET/CT could be clarified as characteristic of PCa metastases by PET/MRI. However, in PET images of the PET/MRI, a reduced signal was observed at the level of the kidneys (in 11 patients) and around the urinary bladder (in 15 patients). This led to reduced SUVs in six lesions. SUV values provided by the PET/MRI system were different in muscles, blood pool, liver and spleen. Conclusion: PCa was detected more easily and more accurately with Ga-PSMA PET/MRI than with PET/CT and with lower radiation exposure. Consequently, this new technique could clarify unclear findings on PET/CT. However, scatter correction was challenging when the specific Ga-PSMA ligand was used. Moreover, direct comparison of SUVs from PET/CT and PET/MR needs to be conducted carefully. [ABSTRACT FROM AUTHOR]

However, many lymph node metastases are located outside the standard ePLND field and contribute to early relapses [[2]]. One lymph node metastasis in the right pelvis was detected by both preoperative mpMRI and SP 68 sp Ga-PSMA-11 PET/CT (A, arrow). Besides one macroscopic lymph node metastasis, two different nodes were palpable (D, arrows). [Extracted from the article]

In the era when positron emission tomography (PET) seems to constitute the most advanced application of nuclear medicine imaging, still the conventional procedure of single photon emission computed tomography (SPECT) is far from being obsolete, especially if combined with computed tomography (CT). In fact, this dual modality imaging technique (SPECT/CT) lends itself to a wide variety of useful diagnostic applications whose clinical impact is in most instances already well established, while the evidence is growing for newer applications. The increasing availability of new hybrid SPECT/CT devices with advanced technology offers the opportunity to shorten acquisition time and to provide accurate attenuation correction and fusion imaging. In this review we analyse and discuss the capabilities of SPECT/CT for improving sensitivity and specificity in the imaging of both oncological and non-oncological diseases. The main advantages of SPECT/CT are represented by better attenuation correction, increased specificity, and accurate depiction of the localization of disease and of possible involvement of adjacent tissues. Endocrine and neuroendocrine tumours are accurately localized and characterized by SPECT/CT, as also are solitary pulmonary nodules and lung cancers, brain tumours, lymphoma, prostate cancer, malignant and benign bone lesions, and infection. Furthermore, hybrid SPECT/CT imaging is especially suited to support the increasing applications of minimally invasive surgery, as well as to precisely define the diagnostic and prognostic profile of cardiovascular patients. Finally, the applications of SPECT/CT to other clinical disorders or malignant tumours is currently under extensive investigation, with encouraging results in terms of diagnostic accuracy. [ABSTRACT FROM AUTHOR]

11C-PK11195 is a radiopharmaceutical for in vivo assessment of peripheral benzodiazepine receptor (PBR) activity using PET. We sought to clarify the metabolic fate of 11C-PK11195 in a test–retest setting using radio-HPLC in comparison with radio-TLC, and the whole-body distribution in humans. In order to evaluate the reproducibility of radio-HPLC metabolite analyses, ten patients with Alzheimer’s disease (AD) underwent two successive 11C-PK11195 examinations on separate days. For comparison of different analytical methods, plasma samples from seven patients were also analysed by radio-TLC. In addition, we evaluated the whole-body distribution of 11C-PK11195 and its uptake in the brain. The level of unmetabolized 11C-PK11195 decreased slowly from 96.3 ± 1.6% (mean±SD) at 5 min to 62.7 ± 8.3% at 40 min after injection. Large individual variation was observed in the amount of plasma 11C-PK11195 radiometabolites. The whole-body distribution of 11C-PK11195 showed the highest radioactivity levels in urinary bladder, adrenal gland, liver, salivary glands, heart, kidneys, and vertebral column. In addition, the hip bone and breast bone were clearly visualized by PET. In patients with AD, 11C-PK11195 uptake in the brain was the highest in the basal ganglia and thalamus, followed by the cortical grey matter regions and the cerebellum. Low 11C-PK11195 uptake was observed in the white matter. Our results indicate that 11C-PK11195 is eliminated both through the renal and hepatobiliary systems. Careful analysis of plasma metabolites is required to determine the accurate arterial input function for quantitative PET measurement. [ABSTRACT FROM AUTHOR]

SP 177 sp Lu-Prostate-specific membrane antigen ( SP 177 sp Lu-PSMA) radioligand therapy (RLT) has demonstrated encouraging efficacy in patients with metastatic castration-resistant prostate cancer (mCRPC) [[1]]. Furthermore, rechallenge with SP 177 sp Lu-PSMA has been described as a potential therapeutic option in patients with an excellent response during initial RLT treatment [[2]]. [Extracted from the article]

The article present a case study of a 47-year-old man with low initial prostate specific antigen (PSA). It mentions the patient presented with intense left iliac bone pain, a nearly undetectable PSA level and a significant increase in carcinoembryonic antigen; and also mentions non-PSA-secreting prostate cancer is rare, has a poor prognosis and can be clinically hard to follow.

Purpose: The purpose of this study was to determine the potential role of the sentinel lymph node (SLN) procedure in limited lymph node dissection in patients with apparently localised prostate carcinoma. Methods: In 27 patients with organ-confined prostate cancer, a single injection of 0.3 ml/30 MBq 99mTc-rhenium sulphur colloid was injected transrectally into the peripheral zone of each lobe of the prostate (total 0.6 ml/60 MBq) under ultrasound guidance. Two hours after injection, scintigraphy was performed. The first step in surgery was the detection and dissection of lymph nodes identified as SLNs. Then, standard lymphadenectomy was performed, consisting in a limited dissection that included all lymph nodes from the obturator fossa and along the external iliac vein. Lymphatic tissue along the hypogastric artery was not systematically removed, except in the presence of SLNs. Results: Mean patient age was 66 years (48-77); the mean serum prostate-specific antigen value was 10.6 ng/ml. In a high proportion of patients (21/27, 77.8%) an SLN was located along the initial centimetres of the hypogastric artery. The second most frequent site of SLNs was in the obturator fossa (11/27 patients, 40.7%), followed by the external iliac area (5/27 patients, 18.5%). Four patients had lymph node metastases, all in SLNs: two in the hypogastric area and two in the obturator fossa. Conclusion: The SLN procedure revealed the individual variability in the lymphatic drainage of the prostate. The main site of SLNs was the hypogastric area, and two of the four metastatic nodes were located at this site. A limited standard pelvic lymphadenectomy, excluding the hypogastric lymph nodes, would have missed half of the lymph node metastases in this study. A radionuclide SLN procedure could assist in the correct staging of patients with early prostate cancer, especially when performing limited lymphadenectomy. [ABSTRACT FROM AUTHOR]

Purpose. 2-(18F)- Fluoro-2-deoxy-D)-glucose positron emission tomography (FDG-PET) is an imaging technique which enables detection of malignancies. FDG-PET has been established as a tool for the diagnosis of pancreatic carcinoma (CA). Early detection is mandatory as cure can only he achieved in non-advanced disease. This is, however, very difficult with conventional radiological techniques. Patients with chronic pancreatitis (CP) are at risk of developing CA. A simple, reliable screening method for malignant degeneration is highly desirable. We set out to investigate whether FDG-PET is able to detect CA in the setting of CP and can fulfiI a potential role in the early detection of CA in CP. Methods. FDG-PFT was performed in 77 CP patients and in six patients with CP complicated by CA (CP + CA). We included 26 CA patients as a positive control. A positive scan was defined as focal FDG accumulation in the pancreas region. Results. In 67 of the 77 CP (87%) patients, pancreatic FDG accumulation was absent. Six patients had significant accumulation. In CA, 24/26 patients had a positive PET. Five out of the six patients with CP + CA had local uptake, while minor uptake was seen in one patient. FDG-PET was positive in almost all CA patients and CP + CA patients. FDG-PET was negative in the large majority (87%) of CP patients, which suggests that a positive PET scan in CP patients must lead to efforts to exclude a malignancy. Conclusion. These data suggest that FDG-PET has a potential role as a diagnostic tool for detecting CA in long-standing CP. [ABSTRACT FROM AUTHOR]

The article discusses the treatment of cerebral metastases in patients with castration-resistant metastatic prostate cancer by surgical resection, chemotherapy, and external beam radiotherapy. Topics discussed include Leucine-Prostate-specific membrane antigen (PSMA)-617 and external radiotherapy, androgen deprivation with Goserelin and chemotherapy with docetaxel, and tracer-avid cerebral metastases.

The article presents the case history of a 47-year-old man with an elevated prostate-specific antigen (PSA) level having a Gleason 9 prostatic adenocarcinoma. A hypermetabolic lesion in the right posterolateral peripheral zone was revealed by (PET)/MRI. The presence of neoplasia in both the same prostate region and lymph node was confirmed by pathological results from prostatectomy and pelvic lymph node dissection.