A Comparison of Globally Applied Prognostic Risk Groups and the Prevalence of Metastatic Disease on Prostate-specific Membrane Antigen Positron Emission Tomography in Patients with Newly Diagnosed Prostate Cancer.

BACKGROUND: Various risk classification systems (RCSs) are used globally to stratify newly diagnosed patients with prostate cancer (PCa) into prognostic groups. OBJECTIVE: To compare the predictive value of different prognostic subgroups (low-, intermediate-, and high-risk disease) within the RCSs for detecting metastatic disease on prostate-specific membrane antigen (PSMA) positron emission tomography (PET)/computed tomography (CT) for primary staging, and to assess whether further subdivision of subgroups would be beneficial. DESIGN, SETTING, AND PARTICIPANTS: Patients with newly diagnosed PCa, in whom PSMA-PET/CT was performed between 2017 and 2022, were studied retrospectively. Patients were stratified into risk groups based on four RCSs: European Association of Urology, National Comprehensive Cancer Network (NCCN), Cambridge Prognostic Group (CPG), and Cancer of the Prostate Risk Assessment. OUTCOME MEASUREMENTS AND STATISTICAL ANALYSIS: The prevalence of metastatic disease on PSMA-PET/CT was compared among the subgroups within the four RCSs. RESULTS AND LIMITATIONS: In total, 2630 men with newly diagnosed PCa were studied. Any metastatic disease was observed in 35% (931/2630) of patients. Among patients classified as having intermediate- and high-risk disease, the prevalence of metastases ranged from approximately 12% to 46%. Two RCSs further subdivided these groups. According to the NCCN, metastatic disease was observed in 5.8%, 13%, 22%, and 62% for favorable intermediate-, unfavorable intermediate-, high-, and very-high-risk PCa, respectively. Regarding the CPG, these values were 6.9%, 13%, 21%, and 60% for the corresponding risk groups. CONCLUSIONS: This study underlines the importance of nuanced risk stratification, recommending the further subdivision of intermediate- and high-risk disease given the notable variation in the prevalence of metastatic disease. PSMA-PET/CT for primary staging should be reserved for patients with unfavorable intermediate- or higher-risk disease. PATIENT SUMMARY: The use of various risk classification systems in patients with prostate cancer helps identify those at a higher risk of having metastatic disease on prostate-specific membrane antigen positron emission tomography/computed tomography for primary staging.

The Probability of Metastases Within Different Prostate-specific Antigen Ranges Using Prostate-specific Membrane Antigen Positron Emission Tomography in Patients with Newly Diagnosed Prostate Cancer.

Background and objectives: The association between prostate-specific antigen (PSA) level and probability of metastatic disease on prostate-specific membrane antigen (PSMA) positron emission tomography/computed tomography (PET/CT) has not yet been established in patients with newly diagnosed prostate cancer (PCa). Our objective was to assess the probability of metastatic disease within different PSA ranges using PSMA PET/CT for initial staging of PCa, and to identify both the anatomical distribution and the predictors of metastases on PSMA PET/CT. Methods: In total, 2193 patients with newly diagnosed PCa were retrospectively studied. PSMA PET/CT was performed for staging purposes between January 2017 and May 2022. The proportion of patients with PSMA-avid metastases, stratified by PSA level, was studied. A vast majority of patients in whom at least one high-risk prognostic factor was present underwent PSMA PET/CT. A multivariable logistic regression analysis was performed to identify the predictors of metastases on PSMA PET/CT using clinical, biochemical, radiological, and pathological variables. Key findings and limitations: The median PSA level at PSMA PET/CT was 14.1 ng/ml. Any metastatic disease (miN1-M1a-c) was observed in 34.7% (763/2193) of all patients and distant metastases (miM1a-c) in 25.4% (557/2193) of patients. The presence of any metastatic disease increased with PSA levels, being 15.4% in men with PSA levels <10 ng/ml and 87.5% in men with PSA levels >100 ng/ml. The multivariable logistic regression analysis found significant associations between the presence of any metastatic disease and PSA subgroups, clinical tumor stage ≥T2, grade group >3, and radiological tumor stage ≥T3b. Conclusions and clinical implications: This is the first large epidemiological study in patients with PCa demonstrating the association between PSA subgroups and metastatic disease on modern imaging PSMA PET/CT. Data from this study can be used to counsel patients on the probability of metastatic disease at the time of PSA screening and to provide guidance on existing guidelines. Patient summary: The prostate-specific antigen level could be used to assess the risk of metastases on prostate-specific membrane antigen positron (PSMA) emission tomography/computed tomography (PET/CT). This knowledge is valuable for selecting patients who will benefit most from metastatic screening with PSMA PET/CT.

Optimization and validation of 18F-DCFPyL PET radiomics-based machine learning models in intermediate- to high-risk primary prostate cancer.

INTRODUCTION: Radiomics extracted from prostate-specific membrane antigen (PSMA)-PET modeled with machine learning (ML) may be used for prediction of disease risk. However, validation of previously proposed approaches is lacking. We aimed to optimize and validate ML models based on 18F-DCFPyL-PET radiomics for the prediction of lymph-node involvement (LNI), extracapsular extension (ECE), and postoperative Gleason score (GS) in primary prostate cancer (PCa) patients. METHODS: Patients with intermediate- to high-risk PCa who underwent 18F-DCFPyL-PET/CT before radical prostatectomy with pelvic lymph-node dissection were evaluated. The training dataset included 72 patients, the internal validation dataset 24 patients, and the external validation dataset 27 patients. PSMA-avid intra-prostatic lesions were delineated semi-automatically on PET and 480 radiomics features were extracted. Conventional PET-metrics were derived for comparative analysis. Segmentation, preprocessing, and ML methods were optimized in repeated 5-fold cross-validation (CV) on the training dataset. The trained models were tested on the combined validation dataset. Combat harmonization was applied to external radiomics data. Model performance was assessed using the receiver-operating-characteristics curve (AUC). RESULTS: The CV-AUCs in the training dataset were 0.88, 0.79 and 0.84 for LNI, ECE, and GS, respectively. In the combined validation dataset, the ML models could significantly predict GS with an AUC of 0.78 (p<0.05). However, validation AUCs for LNI and ECE prediction were not significant (0.57 and 0.63, respectively). Conventional PET metrics-based models had comparable AUCs for LNI (0.59, p>0.05) and ECE (0.66, p>0.05), but a lower AUC for GS (0.73, p<0.05). In general, Combat harmonization improved external validation AUCs (-0.03 to +0.18). CONCLUSION: In internal and external validation, 18F-DCFPyL-PET radiomics-based ML models predicted high postoperative GS but not LNI or ECE in intermediate- to high-risk PCa. Therefore, the clinical benefit seems to be limited. These results underline the need for external and/or multicenter validation of PET radiomics-based ML model analyses to assess their generalizability.

Incidental Detection of Parathyroid Adenoma on 18F-PSMA PET/CT.

ABSTRACT: A 70-year-old man, diagnosed with prostate cancer, was referred to the Department of Nuclear Medicine for tumor staging with prostate-specific membrane antigen (PSMA) PET/CT. High PSMA uptake was observed in the prostate without PSMA-avid lymph nodes or distant metastases. Coincidentally, a PSMA-avid nodule was observed dorsal to the right thyroid lobe. A complementary 4-dimensional CT showed a round nodule of 18 mm with quick contrast enhancement well demarcated from its surroundings. Blood tests revealed elevated serum calcium and parathyroid hormone consistent with primary hyperparathyroidism. Subsequently, parathyroidectomy was performed, and histopathological examination of the nodule confirmed a parathyroid adenoma.

FDG-Avid Granulomatous Lymphocytic Interstitial Lung Disease With Common Variable Immunodeficiency.

ABSTRACT: A 26-year-old woman with known common variable immunodeficiency was referred for FDG PET/CT because of interstitial pulmonary abnormalities and enlarged mediastinal and hilar lymph nodes. FDG PET showed a combination of ground-glass abnormalities and pulmonary nodules, both displaying increased FDG uptake. In addition, multiple FDG-avid axillary, mediastinal, hilar, and inguinal lymph nodes were found. The abnormalities were diagnosed as granulomatous-lymphocytic interstitial lung disease. Cytology of mediastinal lymph nodes yielded only benign disease, without further specification, whereas histology of an excised axillary lymph node showed reactive changes, but no malignancy.

Distant embolisation in infective endocarditis: characteristics and outcomes.

BACKGROUND: Infective endocarditis is a severe and potentially lethal cardiac disease. Recognition of the clinical features of endocarditis, such as distant embolisation, and adequate treatment should be initiated promptly given the grim perspective of upcoming virulent pathogens. METHODS: We report on our registry-based experience with outcomes of consecutive patients with infective endocarditis with distant embolisation. We aimed to describe the patient characteristics of infective endocarditis complicated by distant organ embolisation and the safety aspects of continuing endocarditis treatment at home in these patients. RESULTS: From November 2018 through April 2022, 157 consecutive patients were diagnosed with infective endocarditis. Of them, 38 patients (24%) experienced distant embolisation, either in the cerebrum (n = 18), a visceral organ (n = 5), the lungs (n = 7) or the myocardium (n = 8). Pathogens identified in blood cultures were predominantly streptococcal variants (43%), with only one culture-negative endocarditis case. Of the 18 patients with cerebral embolisation, 12 had neurological complaints and most often discrete abnormal findings on neurological examination. Six of the 8 cardiac embolism patients experienced chest pain before admission. Visceral organ and pulmonary embolism occurred silently. Of the 38 patients with distant embolisation, 17 could be discharged earlier by providing antibiotic treatment at home without complications. CONCLUSION: This registry-based single-centre experience showed an incidence of distant embolisation in daily care of 24%. Cerebral and coronary embolisation provoked symptoms, while visceral emboli remained silent. Pulmonary emboli may present with inflammatory signs. Distant embolisation was not in itself a contra-indication for outpatient endocarditis@home treatment.

Performance of visual, manual, and automatic coronary calcium scoring of cardiac 13N-ammonia PET/low dose CT.

BACKGROUND: Coronary artery calcium is a well-known predictor of major adverse cardiac events and is usually scored manually from dedicated, ECG-triggered calcium scoring CT (CSCT) scans. In clinical practice, a myocardial perfusion PET scan is accompanied by a non-ECG triggered low dose CT (LDCT) scan. In this study, we investigated the accuracy of patients' cardiovascular risk categorisation based on manual, visual, and automatic AI calcium scoring using the LDCT scan. METHODS: We retrospectively enrolled 213 patients. Each patient received a 13N-ammonia PET scan, an LDCT scan, and a CSCT scan as the gold standard. All LDCT and CSCT scans were scored manually, visually, and automatically. For the manual scoring, we used vendor recommended software (Syngo.via, Siemens). For visual scoring a 6-points risk scale was used (0; 1-10; 11-100; 101-400; 401-100; > 1 000 Agatston score). The automatic scoring was performed with deep learning software (Syngo.via, Siemens). All manual and automatic Agatston scores were converted to the 6-point risk scale. Manual CSCT scoring was used as a reference. RESULTS: The agreement of manual and automatic LDCT scoring with the reference was low [weighted kappa 0.59 (95% CI 0.53-0.65); 0.50 (95% CI 0.44-0.56), respectively], but the agreement of visual LDCT scoring was strong [0.82 (95% CI 0.77-0.86)]. CONCLUSIONS: Compared with the gold standard manual CSCT scoring, visual LDCT scoring outperformed manual LDCT and automatic LDCT scoring.

Incidental Findings on 18 F-Fluorocholine PET/CT for Parathyroid Imaging.

Introduction 18 F-choline positron emission tomography/computed tomography (PET/CT) is an upcoming imaging technique for the localization of hyperfunctioning parathyroid glands. However, 18 F-choline is a nonspecific tracer that also accumulates in malignancies, inflammatory lesions, and several other benign abnormalities. The aim of this study was to determine the occurrence and relevance of incidental findings on 18 F-choline PET/CT for parathyroid localization. Materials and Methods 18 F-choline PET/CTs performed in our center for parathyroid localization from 2015 to 2019 were reviewed. Abnormal uptake of 18 F-choline, with or without anatomical substrate on the co-registered low-dose CT and also incidental findings on CT without increased 18 F-choline uptake were recorded. Each finding was correlated with follow-up data from the electronic medical records. Results A total of 388 18 F-choline PET/CTs were reviewed, with 247 incidental findings detected in 226 patients (58%): 82 18 F-choline positive findings with corresponding pathology on CT, 16 without CT substrate, and 149 18 F-choline negative abnormalities on CT. Malignant lesions were detected in 10/388 patients (2.6%). Of all 98 detected 18 F-choline positive lesions, 15 were malignant (15.3%), concerning 4 metastases and 11 primary malignancies: breast carcinoma ( n = 7), lung carcinoma ( n = 2), thyroid carcinoma ( n = 1), and skin melanoma ( n = 1). Conclusion Clinically relevant incidental findings were observed in a substantial number of patients. In 15.3% of the incidental 18 F-choline positive findings, the lesions were malignant. These data contribute to better knowledge of 18 F-choline distribution, enhance interpretation of 18 F-choline PET/CT, and guide follow-up of incidental findings. Attention should especially be paid to breast lesions in this particular patient group with hyperparathyroidism in which women are typically over-represented.

Imaging Dopaminergic Neurotransmission in Neurodegenerative Disorders.

Imaging of dopaminergic transmission in neurodegenerative disorders such as Parkinson disease (PD) or dementia with Lewy bodies plays a major role in clinical practice and in clinical research. We here review the role of imaging of the nigrostriatal pathway, as well as of striatal receptors and dopamine release, in common neurodegenerative disorders in clinical practice and research. Imaging of the nigrostriatal pathway has a high diagnostic accuracy to detect nigrostriatal degeneration in disorders characterized by nigrostriatal degeneration, such as PD and dementia with Lewy bodies, and disorders of more clinical importance, namely in patients with clinically uncertain parkinsonism. Imaging of striatal dopamine D2/3 receptors is not recommended for the differential diagnosis of parkinsonian disorders in clinical practice anymore. Regarding research, recently the European Medicines Agency has qualified dopamine transporter imaging as an enrichment biomarker for clinical trials in early PD, which underlines the high diagnostic accuracy of this imaging tool and will be implemented in future trials. Also, imaging of the presynaptic dopaminergic system plays a major role in, for example, examining the extent of nigrostriatal degeneration in preclinical and premotor phases of neurodegenerative disorders and to examine subtypes of PD. Also, imaging of postsynaptic dopamine D2/3 receptors plays a role in studying, for example, the neuronal substrate of impulse control disorders in PD, as well as in measuring endogenous dopamine release to examine, for example, motor complications in the treatment of PD. Finally, novel MRI sequences as neuromelanin-sensitive MRI are promising new tools to study nigrostriatal degeneration in vivo.

Radiosynoviorthesis: almost seventy years of experience but still somewhat fameless.

Radiosynoviorthesis (RSO) or radiation synovectomy has been practiced for more than half a century, but in many parts of the world, it is still relatively unknown and not used to its full potential in the standard care for chronic, persistent or recurrent synovitis. The working mechanism of RSO is simple yet elegant. Radiopharmaceutical particles are, after injection in the affected synovial joint, gobbled up by phagocytizing subsynovial inflammatory cells. As a consequence, the synovium will be irradiated locally resulting in synovial cell necrosis and inhibition of cell proliferation, which eventually leads to a decrease in the inflammatory response in the joint cavity. In this review RSO is once again brought to the attention and common indications for RSO are discussed. Also, appropriate activities of the administrated radiopharmaceuticals and coadministrated glucocorticoids are provided. Furthermore, a detailed database-assisted chronological overview of published literature of RSO in inflammatory and non-inflammatory diseases, like rheumatoid arthritis, psoriatic arthritis, osteoarthritis and osteochrondomatosis, hemophilic hemarthrosis and pigmented villonodular synovitis (PVNS) is provided. Based upon the published literature an indication of level of evidence of RSO is discussed. There is evidence that RSO is effective in persistent synovitis in patients with a variety of causes for synovitis, although the effectiveness seems to decrease over time. In these patients, RSO may not be used to its full potential in many parts of the world. Results in of RSO in hemophilia patients with hemarthrosis are favourable, however the evidence for the effectiveness of RSO in these patients is less firm and mainly based on case series. The evidence for the efficacy of RSO as adjuvant therapy in PVNS is, at best, of very low quality.

Athletic Osteitis Pubis Detected on 18 F-FDG PET/CT.

ABSTRACT: A 37-year-old male personal trainer presented with debilitating groin pains, fever, and night sweats. Enlarged inguinal lymph nodes were noticed during physical examination, and blood tests showed elevated erythrocyte sedimentation rate and C-reactive protein. 18 F-FDG PET/CT excluded lymphoma and other malignancy but showed intense FDG uptake at the pubic symphysis and cortical erosions of the pubic bones on CT. The patient was diagnosed with osteitis pubis, an inflammatory condition of the pubic symphysis commonly seen in athletes. Treatment with anti-inflammatory drugs was initiated. Within several weeks, pain decreased, and inflammatory markers normalized.

Multi-task Deep Learning of Myocardial Blood Flow and Cardiovascular Risk Traits from PET Myocardial Perfusion Imaging.

BACKGROUND: Advanced cardiac imaging with positron emission tomography (PET) is a powerful tool for the evaluation of known or suspected cardiovascular disease. Deep learning (DL) offers the possibility to abstract highly complex patterns to optimize classification and prediction tasks. METHODS AND RESULTS: We utilized DL models with a multi-task learning approach to identify an impaired myocardial flow reserve (MFR <2.0 ml/g/min) as well as to classify cardiovascular risk traits (factors), namely sex, diabetes, arterial hypertension, dyslipidemia and smoking at the individual-patient level from PET myocardial perfusion polar maps using transfer learning. Performance was assessed on a hold-out test set through the area under receiver operating curve (AUC). DL achieved the highest AUC of 0.94 [0.87-0.98] in classifying an impaired MFR in reserve perfusion polar maps. Fine-tuned DL for the classification of cardiovascular risk factors yielded the highest performance in the identification of sex from stress polar maps (AUC = 0.81 [0.73, 0.88]). Identification of smoking achieved an AUC = 0.71 [0.58, 0.85] from the analysis of rest polar maps. The identification of dyslipidemia and arterial hypertension showed poor performance and was not statistically significant. CONCLUSION: Multi-task DL for the evaluation of quantitative PET myocardial perfusion polar maps is able to identify an impaired MFR as well as cardiovascular risk traits such as sex, smoking and possibly diabetes at the individual-patient level.

Focal PSMA-Positive Pleural Lesion in a Patient With Stage II Prostate Carcinoma.

ABSTRACT: A 70-year-old man with histopathologically proven prostate carcinoma (Gleason, 5 + 5; prostate-specific antigen level, 6.2 µg/mL) was referred for an 18F-PSMA-1007 PET/CT scan. The scan revealed bilateral PSMA uptake in the prostate, representing the primary tumor, but no evidence of PSMA-positive lymph nodes. However, a left-sided ventral pleural thickening showed focal PSMA uptake. Lesion biopsy showed no signs of malignancy, and prostatectomy was performed. The 1-year follow-up CT thorax showed growth of approximately 20% of the pleural lesion. Subsequently, video-assisted thoracic surgery of the lesion was performed. Histopathology showed a solitary fibrous tumor, a rare mesenchymal tumor.

Löfgren Syndrome on 18F-FDG PET/CT: An Acute Manifestation of Sarcoidosis.

ABSTRACT: A 58-year-old man presented with fever, erythema nodosum, and arthralgia of knee and ankle joints. Laboratory data showed signs of inflammation, and chest x-ray revealed bilateral hilar lymphadenopathy. 18F-FDG PET/CT was acquired to analyze the underlying causes and revealed FDG accumulation in thoracic lymphadenopathy and in subcutaneous lesions and periarticular uptake. This typical triad is known as Löfgren syndrome, an acute manifestation of sarcoidosis and which, as this case shows, can be visualized on 18F-FDG PET/CT. It is important to recognize this syndrome and to discriminate it from the classic presentation of sarcoidosis because of its different diagnostic and therapeutic consequences.

Matched-Pair Comparison of 18F-DCFPyL PET/CT and 18F-PSMA-1007 PET/CT in 240 Prostate Cancer Patients: Interreader Agreement and Lesion Detection Rate of Suspected Lesions.

Over 20 different prostate-specific membrane antigen (PSMA)-targeting radiopharmaceuticals for both imaging and therapy have been synthesized. Although variability in biodistribution and affinity for binding to the PSMA receptor is known to exist between different PSMA-targeting radiopharmaceuticals, little is known about the clinical implications of this variability. Therefore, this study analyzed differences in interreader agreement and detection rate between 2 regularly used 18F-labeled PSMA receptor-targeting radiopharmaceuticals: 18F-DCFPyL and 18F-PSMA-1007. Methods: One hundred twenty consecutive patients scanned with 18F-PSMA-1007 were match-paired with 120 patients scanned with 18F-DCFPyL. All 240 PET/CT scans were reviewed by 2 readers and scored according to the criteria of the PSMA Reporting and Data System. Interreader agreement and the detection rate for suspected lesions were scored for different anatomic locations such as the prostate, prostatic fossa, lymph nodes, and bone. Results: Great equality was found between 18F-DCFPyL and 18F-PSMA-1007; however, some clinically relevant and statistically significant differences were observed. 18F-PSMA-1007 detected suspected prostatic or prostatic fossa lesions in a higher proportion of patients and especially in the subcohort scanned for biochemical recurrence. 18F-DCFPyL and 18F-PSMA-1007 showed an equal ability to detect suspected lymph nodes, although interreader agreement for 18F-DCFPyL was higher. 18F-DCFPyL showed fewer equivocal skeletal lesions and higher interreader agreement on skeletal lesions. Most of the equivocal lesions found with 18F-PSMA-1007 at least were determined to be of nonmetastatic origin. Conclusion: Clinically relevant differences, which may account for diagnostic dilemmas, were observed between 18F-DCFPyL and 18F-PSMA-1007. Those findings encourage further studies, as they may have consequences for selection of the proper PSMA-targeting radiopharmaceutical.

"Skull on Fire": Monostotic Paget Disease of the Skull Bone.

An 81-year-old woman was evaluated for a stroke. CT showed no intracranial abnormalities but diffuse patchy aspect of the neurocranium. An MRI and F-NA PET/CT were performed to differentiate between metastases, Paget disease, hyperostosis frontalis interna, and primary malignancy. MRI yielded no additional findings. F-NA PET/CT showed diffusely increased uptake in the skull and 4 spots with intense uptake. No other suspicious skeletal foci were seen elsewhere. Low-dose CT showed no sign of malignancy elsewhere. Image findings together with elevated serum alkaline phosphatase levels, slightly increased calcium levels, and normal phosphorus levels were interpreted as pathognomic for monostotic Paget.

Detection of Recurrent Prostate Cancer Using Prostate-specific Membrane Antigen Positron Emission Tomography in Patients not Meeting the Phoenix Criteria for Biochemical Recurrence After Curative Radiotherapy.

Biochemical recurrence of prostate cancer (PCa) after curative radiotherapy is defined as a prostate-specific antigen (PSA) rise of ≥2 ng/ml above the nadir ("Phoenix criteria", 2005). With the introduction of prostate-specific membrane antigen positron emission tomography (PSMA-PET), the ability to localise PCa recurrences has increased markedly. Here, we reviewed 315 patients scanned with PSMA-PET after curative radiotherapy in the Prostate Cancer Network Amsterdam (2015-2018). Sixty-three patients (20.3%) were scanned below the Phoenix threshold (PSA rise <2.0 ng/ml). In 53 of these patients (84.1%), PSMA-PET-avid lesions were detected nonetheless: 21 patients (33.3%) revealed a local recurrence as a single site of disease, 32 patients (50.8%) harboured metastatic PCa. Besides rising PSA, no predictors were identified that prompted early PSMA-PET imaging. In this communication, we report on the frequent detection of metastatic PCa with PSMA-PET in men below the Phoenix PSA threshold. These findings are a plea for re-evaluation of current diagnostic work-up for rising PSA values after radiotherapy, as early detection of recurrences might refine salvage and/or adjuvant therapies. PATIENT SUMMARY: This study reports on the unexpected detection of prostate cancer (PCa) recurrences with prostate-specific membrane antigen positron emission tomography in patients treated with radiotherapy. This calls for re-evaluation of the current criteria for recurrent PCa after radiotherapy.

Relation between pharmacological stress ECG, 13NH3-PET/CT outcome and the occurrence of cardiac events during follow-up in women with chest pain.

AIM: Evaluation of major adverse cardiovascular events (MACE) in women referred for NH3-PET/CT in relation to scan outcome and pharmacological stress ECG (PxECG) results. PATIENTS AND METHODS: Six hundred twenty-four women, referred for NH3-PET/CT between 2012 and 2016, were included. Demographic data and MACE during follow-up (407 ± 207 days) were retrieved from electronic patient charts. NH3-PET/CT was scored as either normal or abnormal. PxECG was scored as negative, non-diagnostic or positive. PxECG was compared with NH3-PET/CT and related to MACE. RESULTS: The NH3-PET/CT was normal in 482/624 (77%) and abnormal in 142/624 (23%). PxECG was negative in 234/624 (38%), non-diagnostic in 365/624 (58%) and positive in 25/624 (4%). NH3-PET/CT was normal in 87, 71 and 72% with normal, nondiagnostic and positive PxECG, respectively. 41/624(7%) experienced a MACE, 38 with abnormal NH3-PET/CT versus three with normal NH3-PET/CT (P < 0.001). MACE occurred in 5/234 (0.9%), 31/365 (8%) and 5/25 (20%) with normal, non-diagnostic and positive PxECG, respectively (P < 0.001). No MACEs were seen in 204 with both normal PxECG and NH3-PET/CT versus 5/30(17%) with normal PxECG but abnormal NH3-PET/. No MACE occurred in 3/260(1%) with non-diagnostic PxECG and normal NH3-PET/CT versus 28/105(27%) with non-diagnostic PxECG and abnormal NH3-PET/CT. 0/18 with positive PxECG and normal NH3-PET/CT showed MACE versus 5/7(71%) with a positive PxECG and abnormal NH3-PET/CT. CONCLUSION: Normal NH3-PET/CT is most prevalent in women with normal PxECG. The occurrence of MACE during follow-up is more frequently related to an abnormal NH3-PET/CT than to PxECG. Furthermore, in women with positive PxECG but normal NH3-PET/CT no MACE are to be expected.

Dynamic 18F-fluorocholine PET/CT for parathyroid imaging in patients with primary hyperparathyroidism.

OBJECTIVE: In the past few years, F-fluorocholine PET/CT has been established as a promising imaging technique for preoperative localization of parathyroid adenomas, but the optimal time point to start PET/CT acquisition after tracer injection is yet unknown. The aim of the present study was to assess the optimal time frame to acquire the PET/CT images and to evaluate the ability of dynamic imaging to differentiate parathyroid adenomas from active lymph nodes, a common cause for false-positive scan results. PATIENTS AND METHODS: Patients with primary hyperparathyroidism who had undergone a dynamic F-fluorocholine PET/CT positive for parathyroid disease and who subsequently underwent successful parathyroidectomy were retrospectively included in this study. On the 20 minutes dynamic images, standardized uptake value measurements were acquired per 1 minute frame for the parathyroid adenoma, the thyroid gland, blood pool activity, and, if present, lymph node activity. RESULTS: A total of 101 patients were included in this study. Time-activity curves showed a decrease of activity in parathyroid and thyroid glands, with faster wash-out from the thyroid gland and on average a stable, lower activity in lymph nodes. Blood pool activity was particularly present in the first 2 minutes. Differentiation of a parathyroid adenoma from active lymph nodes was best before 5 minutes, but no definitive cutoff value could be determined. Differentiation of a parathyroid adenoma from the thyroid gland was best after 10 minutes. CONCLUSION: Dynamic imaging starting at the early time point of 2 minutes after injection of F-fluorocholine is useful for characterization of hyperfunctioning parathyroid glands.

Incidental Breast Carcinoma Detected With 13N-NH3 Cardiac PET Imaging.

A 78-year-old woman with chest pain and a history of pacemaker implantation for arrhythmia underwent myocardial perfusion imaging by means of N-NH3 cardiac PET/CT. N-NH3 cardiac PET showed no signs of ischemia or infarction. Incidentally, a nodule with increased N-NH3 activity was observed in the right breast. Histopathologic examination revealed invasive ductal carcinoma.