Intra-individual comparison of prostate-specific membrane antigen positron emission tomography/computed tomography versus bone scan in detecting skeletal metastasis at prostate cancer diagnosis.

OBJECTIVES: To compare the diagnostic performance and radiological staging impact of 68 Ga-prostate-specific membrane antigen positron emission tomography/computed tomography (PSMA PET/CT) compared to 99 Tc whole-body bone scan (WBBS) for the detection of skeletal metastasis in the primary staging of prostate cancer (PCa). PATIENTS AND METHODS: A prospective institutional database was retrospectively examined for patients who underwent both PSMA PET and WBBS within a 1 week interval for PCa primary staging. Lesions were categorised as 'negative', 'equivocal', or 'definite' based on nuclear medicine physician interpretation. Metastatic burden was characterised for each imaging modality according to three groups: (i) local disease (no skeletal metastases), (ii) oligometastatic disease (three or fewer skeletal metastases), or (iii) polymetastatic disease (more than three skeletal metastases). RESULTS: There were 667 patients included. The median (interquartile range) prostate-specific antigen level was 9.2 (6.2-16) ng/mL and 60% of patients were high risk according to a modified D'Amico risk classification. The overall distribution of skeletal metastasis detection changed across the two scans overall (P = 0.003), being maintained within high-risk (P = 0.030) and low-risk (P = 0.018) groups. PSMA PET/CT identified more definite skeletal metastases compared to WBBS overall (10.3% vs 7.3%), and according to risk grouping (high: 12% vs 9%, intermediate: 4% vs 1%). Upstaging was more common with PSMA PET/CT than WBBS (P = 0.001). The maximum standardised uptake value (SUVmax ) of the primary tumour was associated with upstaging of skeletal metastases on PSMA PET/CT (P = 0.025), while age was associated with upstaging on WBBS (P = 0.021). The SUVmax of the primary tumour and metastases were both higher according to extent of metastatic disease (P = 0.001 and P < 0.001, respectively). CONCLUSIONS: More skeletal metastases were detected with PSMA PET/CT than WBBS, resulting in a higher upstaging rate mostly in high-risk patients. The SUVmax of the primary tumour and metastases was associated with upstaging.

Peritoneal Carcinomatosis From Metastatic Prostate Cancer Identified on 68 Ga-Prostate-Specific Membrane Antigen PET/CT.

ABSTRACT: A 69-year-old man with locally advanced prostate adenocarcinoma (Gleason score 9), who had completed hormone therapy and definitive radiotherapy, presented to hospital with abdominal pain and distension. A CT scan of the abdomen and pelvis revealed ascites and extensive peritoneal/omental nodules. Serum prostate-specific antigen was not raised (0.07 µg/L). 68 Ga-prostate-specific membrane antigen (PSMA) PET/CT demonstrated PSMA-avid disease in the prostate and widespread PSMA-avid peritoneal/omental and liver metastases but with no PSMA-avid bony metastases. Peritoneal nodule biopsy confirmed metastatic prostate cancer.

Comparison between PSMA PET/CT and MRI for Characterizing Hepatocellular carcinoma: A Real-World Study.

Prostate specific membrane antigen (PSMA) is expressed by hepatocellular carcinoma (HCC). PSMA PET/CT has potential as an imaging agent for the detection of HCC including early diagnosis and monitoring for recurrence following surgical resection. This study aims to compare PSMA PET to standard surveillance imaging in the detection of HCC. Patients with suspected or treated HCC were prospectively recruited from a tertiary hospital outpatient clinic. In addition to routine surveillance imaging as recommended by the multidisciplinary team, a PSMA PET/CT was performed. Imaging and clinical characteristics were compared over a follow-up period of up to 12 months. In a cohort of 19 patients with known HCC or suspected recurrent HCC, PSMA PET/CT had similar efficacy to MRI for the detection of HCC, with a sensitivity of 91% and a specificity of 70% and sensitivity of 87% and a specificity of 73% for PSMA PET/CT and MRI, respectively. PSMA PET/CT had a higher negative predictive value of 90%. In this relatively large single centre study, PSMA is shown to have promising equivalence in performance and its role should be further evaluated in multi-centre prospective trials.

A rare case of urachal mucinous adenocarcinoma detected by 18F-FDG PET/CT and MRI.

Urachal adenocarcinomas are rare cancers of the urinary bladder. Both CT and MRI are useful imaging modalities for the diagnosis and evaluation of urachal adenocarcinoma. Unlike CT or MR, there have been variable FDG PET findings with urachal tumours potentially due to considerable variation in their hypermetabolism. We present the case of a 24 year-old female patient who was diagnosed with urachal mucinous adenocarcinoma with characteristic features on CT and MRI which also exhibit moderately increased FDG avidity.

Solitary Femoral Nodal Metastasis Identified With 68Ga-Prostate-Specific Membrane Antigen PET/CT.

ABSTRACT: A 66-year-old man was referred for a 68Ga-prostate-specific membrane antigen (PSMA) PET/CT scan for primary staging of Gleason 8 prostatic adenocarcinoma. The PET/CT images confirmed PSMA activity in the bilateral prostatic apex in keeping with the known malignancy. An intensely PSMA-avid focus was also noted in a nonenlarged right femoral lymph node with no evidence of PSMA-avid metastatic disease elsewhere. Subsequent core biopsy and histopathology confirmed a solitary metastatic focus of prostatic adenocarcinoma in a right femoral lymph node.

Solitary 68Ga-PSMA-Avid Proximal Tibial Prostatic Adenocarcinoma Metastasis Mimicking Enthesopathy.

A 76-year-old man with previously treated prostatic adenocarcinoma (Gleason 8) was referred for a Ga-prostate-specific membrane antigen PET/CT scan due to a rising serum PSA level. An intensely PSMA-avid focus was demonstrated in the left proximal tibia with no evidence of local recurrence or metastatic disease elsewhere. This was diagnosed and managed as enthesopathy. A Tc-MDP bone scan with SPECT/CT performed 9 months later confirmed an intensely osteoblastic mixed lytic/sclerotic metastasis at the left proximal tibia.

68Ga-Prostate-Specific Membrane Antigen Solitary Base of Skull Prostate Adenocarcinoma Metastasis.

A 74-year-old man with prostate adenocarcinoma (Gleason 7) was referred for Ga-prostate-specific membrane antigen (PSMA-HBED-CC) PET/CT scan for staging. Findings confirmed the prostate malignancy and demonstrated a solitary metastasis in the left skull base, with no evidence of regional or distant metastasis elsewhere. Solitary base of the skull metastasis may be subtle and easily overlooked, highlighting the need for thorough evaluation of the region.

Solitary 18F-fluorodeoxyglucose avid spinous process cholangiocarcinoma metastasis proven on CT guided percutaneous needle bone biopsy.

A 65-year-old female with newly diagnosed cholangiocarcinoma was referred for a FDG PET/CT for initial staging. There was a region of moderate FDG avidity localizing to the hepatic hilum representing the primary site of malignancy. An unexpected moderately FDG avid focus was demonstrated in the spinous process of the T11 vertebra with no corresponding mass lesion seen on low dose CT and no evidence of distant metastatic disease elsewhere. A percutaneous CT guided needle bone biopsy was performed which confirmed a solitary T11 spinous process metastasis on histopathology.

Incidental prostate-specific membrane antigen-avid meningioma detected on 68Ga-prostate-specific membrane antigen PET/CT.

A 70-year-old gentleman with a history of Gleason score 7 (3 + 4) prostate adenocarcinoma was treated with radical prostatectomy with clear surgical margins. Postoperatively his prostate specific antigen was undetectable. However, his prostate specific antigen was slowly rising and he was referred for a 68Galium-Prostate Specific Membrane Antigen (PSMA) PET/CT scan. Findings were suggestive of local prostatic cancer recurrence with no evidence of nodal or distant metastasis. An incidental PSMA avid focus was noted in the left frontal lobe, inseparable from the left frontal bone laterally. Subsequent MRI findings were consistent with meningioma. Meningioma is the most common primary brain tumor and may be a cause of false positive prostate cancer metastasis due to 68Ga-PSMA uptake.

68Ga-PSMA PET/CT versus CT and bone scan for investigation of PSA failure post radical prostatectomy.

OBJECTIVE: To evaluate the use of Gallium-68 prostate-specific membrane antigen positron emission tomography/computed tomography (68Ga-PSMA PET/CT), compared with conventional CT abdomen/pelvis (CTAP) and whole body single photon emission CT bone scan (BS), for detection of local or distant metastasis following biochemical failure/recurrence in post-prostatectomy patients. METHODS: We conducted a review of our prospectively maintained, institutional database to identify 384 patients with post-prostatectomy biochemical failure/recurrence who underwent PSMA PET/CT, CTAP and BS from February 2015 to August 2017 in Nepean Hospital, tertiary referral centre. The results of the three imaging modalities were analysed for their ability to detect local recurrence and distant metastases. PSMA PET/CT and CTAP imaging were separately performed on the same day and the BS was performed within several days (mostly in 24 h). Difference in detection rates was determined between the modalities and the Chi square test was used to determine significance. RESULTS: A total of 384 patients were identified with a median prostate-specific antigen (PSA) of 0.465 ng/mL (interquartile range =0.19-2.00 ng/mL). Overall, PSMA PET/CT was positive for 245 (63.8%) patients whereas CTAP and BS were positive in 174 patients (45.3%). A total of 98 patients (25.5%) had local or distant metastasis detected on PSMA only, while 20 patients (5.2%) had recurrences detected on CTAP but not on PSMA PET/CT. CONCLUSION: The use of PSMA PET/CT has a higher detection rate of predicted local or distant metastasis compared to CTAP and BS in the staging of patients with biochemical recurrences after radical prostatectomy.

68Ga-Prostate-Specific Membrane Antigen Uptake in Dissecting Abdominal Aortic Aneurysm.

An 81-year-old man with prostate adenocarcinoma (Gleason 4 + 3 = 7) treated with brachytherapy and intermittent androgen deprivation therapy was referred for serial Ga-prostate-specific membrane antigen (PSMA-HBED-CC) PET/CT scans for rising prostate-specific antigen. Findings were suggestive of local prostatic recurrence and nodal metastases. An incidental PSMA-avid focus was noted in the anterior wall of an infrarenal aortic aneurysm, with a contrast-enhanced hyperdense region surrounded by a semilunar hypodense region anteriorly, consistent with enlarging dissecting thrombus. Increased PSMA avidity in atherosclerotic hypertensive lesions may relate to active plaque instability, indicating a need for further evaluation.

Hibernoma Demonstrated on 68Ga-DOTATATE PET/CT.

A 60-year-old woman with recently diagnosed neuroendocrine tumors underwent staging Ga-DOTATATE PET/CT, which revealed focal uptake within the right sacral ala. Histopathology of the right sacral ala confirmed hibernoma. This case illustrates that hibernoma can be a cause of false-positive intraosseous accumulation of Ga-DOTATATE.

Incidental Detection of Splenic Hemangioma on 68Ga-PSMA PET/CT.

A 73-year-old man underwent a Ga-PSMA-HBED-CC 11 PET/CT for evaluation of rising PSA in the context of previous radical retropubic prostatectomy and salvage radiotherapy for prostatic adenocarcinoma. There was no definite PSMA avid recurrence in the prostatic bed. Intense PSMA avid uptake was seen in the anterior aspect of the spleen. Further characterization with multiplanar multisequence pre- and post-IV contrast MRI of the upper abdomen with arterial, portal venous, and delayed phase acquisitions revealed a lesion with appearances consistent with a splenic hemangioma.

Bronchiectasis as a Cause of Elevated CA-19-9 Demonstrated on 18F-FDG PET/CT.

A 64-year-old woman with a history of weight loss and a markedly elevated serum carbohydrate antigen 19-9 level of 560 U/mL was referred for an F-FDG PET study to evaluate for occult malignancy. In addition to the weight loss, she had suffered from a chronic cough secondary to bronchiectasis and had been investigated for a suspected gastrointestinal malignancy. Multiple FDG-avid foci were detected throughout both lungs on FDG PET, corresponding to areas of bronchiectasis on CT with no obvious suspicious FDG-avid foci elsewhere. This supported an inflammatory process causing her elevated carbohydrate antigen 19-9 rather than malignancy.

Hepatic Falciform Artery Demonstrating MAA Uptake in the Anterior Abdomen Prior to Embolization.

A 58-year-old man was referred for selective internal radiation therapy for locally advanced unresectable hepatocellular carcinoma. Intra-arterial particle perfusion scintigraphy was performed with SPECT/CT following intra-arterial injection of Tc macroaggregated albumin. Angiography demonstrated a hepatic falciform artery, a feeding artery of the ligamentum teres, whereas scintigraphy demonstrated tracer uptake in the mid-anterior abdominal wall. The hepatic falciform artery was subsequently embolized and the repeat angiogram confirmed successful occlusion. Subsequent post-selective internal radiation therapy PET/CT images did not reveal any tracer uptake in the mid-anterior abdominal wall.

Pitfalls in Gallium-68 PSMA PET/CT Interpretation-A Pictorial Review.

The novel Gallium-68 prostate-specific membrane antigen (PSMA)-bis [2-hydroxy-5-(carboxyethyl)benzyl] ethylenediamine-diacetic acid positron emission tomography (PET) tracer is increasingly used in the evaluation of prostate cancer, particularly in the detection of recurrent disease. However, PSMA is expressed in nonprostatic tissues, as well as in other pathologic conditions. Here we illustrate such interpretive pitfalls with relevant images that one may encounter while reporting PSMA PET/CT. This study aims to show variation in physiological distribution of PSMA activity and uptake in various benign and neoplastic disorders that may be misinterpreted as prostatic metastatic disease. These pitfalls are illustrated to enhance awareness, aiding a more accurate interpretation of the study. Retrospective database of all (68)Ga PSMA PET/CT was created and reviewed. In total, 1115 PSMA PET/CT studies performed between February 27, 2015, and May 31, 2017, were reviewed. Any unusual uptake of PSMA was documented, described, and followed up. All cases were then subdivided into the following 4 categories: physiological uptake, benign pathological uptake, nonprostatic neoplastic uptake, and miscellaneous uptake. A variety of nonprostatic tissues and lesions, including accessory salivary gland, celiac ganglion, gall bladder, Paget's bone disease, reactive lymph nodes, non-small cell lung cancer, renal cell cancer, and neuroendocrine tumor, were found to show PSMA uptake. PSMA uptake is not prostate-specific and can be taken up physiologically and pathologically in nonprostatic tissue. It is important for reporting physicians to recognize these findings and instigate appropriate investigations when required while avoiding unnecessary procedures in physiological variation.

Incidental PSMA Uptake in an Undisplaced Fracture of a Vertebral Body.

A 50-year-old man with recently diagnosed prostate cancer was referred for Ga-prostate-specific membrane antigen (PSMA) PET/CT with elevated prostate-specific antigen. PET/CT demonstrated increased PSMA uptake in an undisplaced transverse fracture of the L1 vertebral body. This case illustrates that PSMA uptake can occur in a transverse vertebral body fracture and is a benign cause of PSMA uptake.

Incidental 99mTc-DTPA Uptake in Tarlov Cysts on Radionuclide SPECT/CT Cisternography.

Sacral perineural cysts are also known as Tarlov cysts. A 58-year-old man with suspected intracranial hypotension was evaluated with Tc-DTPA radionuclide cisternography. Radionuclide planar and SPECT/CT cisternography revealed Tc-DTPA uptake in sacral lesions. Spine MRI confirmed Tarlov cysts at the S1 and S2 levels.

Incidental Prostate-Specific Membrane Antigen Uptake in a Peripheral Nerve Sheath Tumor.

A 66-year-old man with recently diagnosed prostate cancer (Gleason score 9) was referred for Ga-prostate-specific membrane antigen (PSMA) PET/CT with prostate-specific antigen level of 7.5 µg/L. PET/CT demonstrated increased PSMA uptake (SUVmax 4.7) in a soft tissue density in the left adductor compartment. MRI and cytopathology of the biopsied soft tissue density was compatible with a peripheral nerve sheath tumor. This case illustrates that PSMA uptake can occur in a peripheral nerve sheath tumor and should be taken into consideration as a benign cause of PSMA uptake.