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.

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.

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.

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.

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.

18F-DCFPyL Uptake in an Incidentally Detected Follicular Lymphoma by PET/CT Performed for Biochemically Recurrent Prostate Cancer.

A 75-year-old man, treated with curative intent for histopathologically proven prostate cancer (initial prostate-specific antigen, 27 ng/mL; Gleason 4 + 5 = 9) through external beam radiation therapy in 2010 in combination with 3 years of androgen deprivation therapy (leuprorelin), underwent F-DCFPyL PET/CT for biochemical recurrence with a prostate-specific antigen of 4.1 ng/mL in February 2019. Multiple pelvic and some para-aortic lymph nodes showed highly increased F-DCFPyL uptake, suspicious for metastases. Incidentally, a solid mesenteric mass and mesenteric lymph nodes with moderately increased F-DCFPyL uptake were found. Upon histopathological evaluation, this proved to be a low-grade follicular lymphoma.

Parathyroid imaging with 18F-fluorocholine PET/CT as a first-line imaging modality in primary hyperparathyroidism: a retrospective cohort study.

BACKGROUND: 18F-fluorocholine (FCH) PET/CT is a promising technique for visualizing hyperfunctioning parathyroid glands in hyperparathyroidism. It is still under debate whether to use this technique as a first-line imaging modality or to use it when conventional techniques such as 99mTc-sestamibi scintigraphy or ultrasonography are inconclusive. This study evaluates FCH PET/CT as a first-line modality. METHODS: Patients with primary hyperparathyroidism, referred between June 2015 and December 2018 for FCH PET/CT as a first-line imaging method, were included in this study. Baseline characteristics, clinical data, scan results, and type of treatment were recorded. The rate of correct detection was calculated on a per patient-based and a per lesion-based analysis. The reference standard comprised histopathological results, intraoperative response to parathyroidectomy, and clinical follow-up. RESULTS: Two hundred and seventy-one patients were included, of which 139 patients underwent parathyroidectomy, 48 were treated with calcimimetics, and 84 patients received further follow-up without active treatment. In the surgically treated group, a single adenoma was suspected in 127 scans, double adenoma in three scans, and one scan showed evidence of three hyperfunctioning glands. In eight scans, no lesions were visualized. A total of 154 parathyroid glands were surgically removed. The rate of correct detection was calculated at 96% and 90%, on a per patient-based and per lesion-based analysis, respectively. CONCLUSION: This retrospective study in a large cohort shows high detection rates of FCH PET/CT in primary hyperparathyroidism, which is in accordance to literature. The use of FCH PET/CT as a first-line imaging modality in preoperative planning of parathyroid surgery may therefore be a suitable choice.

18F-DCFPyL PET/CT in a Single Large Metastasis With Prostate-Specific Antigen Level of 856 ng/mL.

Literature shows that prostate-specific membrane antigen (PSMA) PET/CT may detect biochemical recurrence of prostate cancer at low prostate-specific antigen (PSA) levels, including detection of oligometastatic disease and hence direct metastasis-directed therapy. Although it is generally accepted that higher PSA values indicate higher disease burden, few data are available on the relation between PSA levels and number of detected metastases on PSMA PET/CT. This report demonstrates a patient with high PSA levels (856 ng/mL) at time of biochemical recurrence that showed only 1 metastasis on PSMA PET/CT. Combined androgen deprivation therapy and radiation therapy resulted in a complete biochemical response.

Dual-Time-Point 18F-Fluorocholine PET/CT in Parathyroid Imaging.

18F-fluorocholine (18F-FCH) PET/CT is a promising and increasingly used scan technique in the preoperative imaging of parathyroid adenoma. Several acquisition methods have been evaluated in the literature, but the optimal image acquisition time point after administration of the tracer is still under debate. Methods: Patients who had hyperparathyroidism, underwent dual-time-point 18F-FCH PET/CT (image acquisition, 5 min; 60 min after injection), and had histologically proven pathologic parathyroid glands were retrospectively included in the study. Early and late images were compared both visually and quantitatively. Results: Sixty-four patients were included, and a total of 71 parathyroid glands were surgically removed. Visually, there were no differences between early and late images of hyperfunctioning parathyroid glands in 44 patients (69%); in 13 patients (20%), visualization on early images was better; in 6 patients (9%), visualization of hyperfunctioning glands was best on late images; and in 1 patient (2%), the lesion was exclusively visualized on late images. For the total cohort, there was a significant decrease in 18F-FCH uptake in the glands on late versus early time points (P = 0.001), but there was a significant increase in the ratio of parathyroid uptake to thyroid uptake (P = 0.037). The group of patients with better visualization on early images showed a decrease over time in both parathyroid uptake and the ratio of parathyroid uptake to thyroid uptake, significant in comparison to those in both the group with better visualization at later time points and the group in which visualization was similar at both time points (P values of 0.000-0.018). There were no significant differences in 18F-FCH uptake and the ratio of parathyroid uptake to thyroid uptake between the latter 2 groups (P values of 0.200-0.709). Conclusion: In most patients (89%), hyperfunctioning parathyroid glands were adequately visualized on early imaging; however, in a subset of patients (11%), such glands were best visualized at later time points. Therefore, we recommend the acquisition of dual-time-point images in parathyroid imaging with 18F-FCH PET/CT or the creation of an opportunity to acquire additional late images after review of early images when findings are inconclusive.

Choline PET/CT in parathyroid imaging: a systematic review.

One of the most promising imaging techniques in primary hyperparathyroidism is PET/CT with choline-based tracers. To investigate the current evidence of these tracers in localizing parathyroid adenoma, a systematic review was performed. A comprehensive literature search was carried out and eligible studies were analyzed. Data were extracted, the level of evidence was scored, and performance data were pooled to calculate the weighted detection rate. Eleven articles were included in this study. The pooled detection rate was 97 and 94% on per patient-based and per lesion-based analysis, respectively. There was considerable heterogeneity between studies and the level of evidence was determined to be 3a-, following Oxford criteria. Choline PET/CT has shown favorable results in detection of hyperfunctioning parathyroid tissue and may replace conventional technetium-99m-sestamibi scintigraphy in preoperative planning of parathyroid surgery. However, the quality of current evidence is moderate, and additional high-quality studies are needed to confirm these numbers.

Tertiary Hyperparathyroidism With Renal Osteodystrophy on 18F-Fluorocholine PET/CT.

A 27-year-old man, with a history of chronic renal failure due to obstructive uropathy, treated with hemodialysis and awaiting kidney transplantation, presented with tertiary hyperparathyroidism. Despite regulation of phosphate and calcium and treatment with cinacalcet, the serum parathyroid hormone levels remained elevated. The patient was referred for parathyroidectomy, and a F-fluorocholine PET/CT was acquired for preoperative planning. Besides visualization of the hyperfunctioning parathyroid glands, the scan also showed a typical picture of renal osteodystrophy, a finding on F-fluorocholine PET/CT that has not been reported before.

Accuracy of 18F-NaF PET/CT in bone metastasis detection and its effect on patient management in patients with breast carcinoma.

OBJECTIVE: Determination of the accuracy of sodium fluorine-18-fluoride (F-NaF) PET/computed tomography (CT) for the evaluation of bone metastases, and the impact on patient management in breast cancer patients. PATIENTS AND METHODS: Patients with breast cancer, referred for F-NaF PET/CT between February 2014 and June 2016, were included in a database. Baseline characteristics, clinical indication, definitive diagnosis according to follow-up data, as well as changes in patient management were recorded. Follow-up was performed during a period of at least 6 months using histopathologic, medical imaging, biochemical, and clinical data. RESULTS: A total of 118 patients were included in the study. Indications for F-NaF PET/CT included primary staging (12%), follow-up (31%), bone pain (52%), abnormal laboratory findings (5%), and evaluation of equivocal osseous lesions on other imaging modalities (3%). Bone metastases were found in 42%, whereas 53% of the scans were negative and 5% yielded equivocal results. Correlation with the reference standard yielded a sensitivity of 0.96, a specificity of 0.91, a positive predictive value of 0.89, a negative predictive value of 0.97, and an accuracy of 0.93. In 25% of the patients, the scan results led to alterations in patient management. F-NaF PET/CT for the evaluation of bone pain showed no explanation in 29%, benign pathology in 66%, and bone metastases in 5%. CONCLUSION: In the present cohort of patients with breast cancer, F-NaF PET/CT detected bone metastases in 42% with an accuracy of 0.93. The scan results led to a change in patient management in 25%. In the evaluation of bone pain, an explanation for pain was found in 71% of the scans.

Metastasized 18F-DCFPyL-Negative Prostatic Adenocarcinoma Without Neuroendocrine Differentiation.

A 76-year-old man with histopathologically proven prostate cancer (initial prostate-specific antigen 110 ng/mL, Gleason 3 + 4 = 7) received F-DCFPyL PET/CT for initial staging. Both the primary tumor and pathologically enlarged pelvic lymph nodes showed no increased F-DCFPyL uptake. Subsequent histopathologic lymph node biopsy revealed prostate cancer metastasis. Prostate-specific membrane antigen tracers, such as F-DCFPyL, are promising radiopharmaceuticals for prostate cancer imaging. False-negative prostate-specific membrane antigen PET/CT findings have been reported earlier for prostate tumors with neuroendocrine differentiation. However, this report presents false-negative F-DCFPyL PET findings of an adenocarcinoma of the prostate without neuroendocrine differentiation.