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Recent advances in 3-dimensional visualization of volumetric computed tomography data have led to the novel technique of cinematic rendering (CR), which provides photorealistic images with enhanced surface detail and realistic shadowing effects that are generally not possible with older methods such as volume rendering. The emergence of CR coincides with the increasingly widespread availability of virtual reality (VR)/augmented reality (AR) interfaces including wearable headsets. The intersection of these technologies suggests many potential advances, including the ability of interpreting radiologists to look at photorealistic images of patient pathology in real time with surgeons and other referring providers, so long as VR/AR headsets are deployed and readily available. In this article, we will present our initial experience with viewing and manipulating CR images in the context of a VR/AR headset. We include a description of key aspects of the software and user interface, and provide relevant pictorial examples that may help potential adopters understand the initial steps of using this exciting convergence of technologies. Ultimately, trials evaluating the added value of the combination of CR with VR/AR will be necessary to understand the potential impact of these methods on medical practice.

The aim of the review is to provide an update on the current and evolving approaches to diagnosing the challenging clinical entity of renal oncocytoma.Renal oncocytoma is being increasingly recognized among patients with renal masses, and it can be found in up to 50% of benign small renal masses (SRMs) less than 4 cm. Renal oncocytomas have benign clinical biology but distinguishing them from some of the other renal masses with more malignant potential can be challenging due to overlapping imaging, histologic, and immunophenotypic characteristics. Increasing integration of various imaging modalities, histologic characteristics, cytogenetics, and molecular and metabolic signatures is helping better define and characterize renal masses.Evolving and complementary diagnostic approaches, including at the molecular level, are continuing to help refine the classification of renal tumors, with implications on their clinical behavior and ultimately clinical management.

Fibroblast activation protein (FAP) has emerged as a novel target for FAP inhibitor (FAPI)-directed molecular imaging and endoradiotherapy (ERT). We aimed to assess the interobserver agreement rates for interpretation of 68Ga-FAPI-4 PET/CT and decision for ERT.A random order of 68Ga-FAPI-4 PET/CTs from 49 oncology patients were independently interpreted by 4 blinded readers. Per scan, visual assessment was performed, including overall scan impression, number of organ/lymph node (LN) metastases, and number of affected organs/LN regions. Moreover, a maximum of 3 target lesions, defined as largest in size and/or most intense, per organ compartment were identified, which allowed for an additional quantitative interobserver assessment of LN and organ lesions. To investigate potential reference tissues, quantification also included unaffected liver parenchyma and blood pool. Readers also had to indicate whether FAPI-directed ERT should be considered (based on intensity of uptake and widespread disease). Interobserver agreement rates were evaluated using intraclass correlation coefficients (ICCs) and interpreted according to Cicchetti (with 0.4-0.59 indicating fair, and 0.6-0.74 good, agreement).On a visual basis, the agreement rate for an overall scan impression was fair (ICC, 0.42; 95% confidence interval [CI], 0.27-0.57). The concordance rate for number of affected LN areas was also fair (ICC, 0.59; 95% CI, 0.45-0.72), whereas the number of LN metastases, number of affected organs, and number of organ metastases achieved good agreement rates (ICC, ≥0.63). In a quantitative analysis, concordance rates for LN were good (ICC, 0.70; 0.48-0.88), but only fair for organ lesions (ICC, 0.43; 0.26-0.60). In regards to background tissues, ICCs were good for unaffected liver parenchyma (0.68; 0.54-0.79) and fair for blood pool (0.43; 0.29-0.58). When readers should decide on ERT, concordance rates were also fair (ICC, 0.59; 95% CI, 0.46-0.73).For FAPI-directed molecular imaging and therapy, a fair to good interobserver agreement rate was achieved, supporting the adoption of this radiotracer for clinical routine and multicenter trials.

PURPOSE: Prostate specific membrane antigen targeted (18)F-DCFPyL positron emission tomography/computerized tomography may offer superior image quality and sensitivity for the detection of biochemically recurrent prostate cancer. We examined the association of Gleason sum, serum prostate specific antigen and prostate specific antigen doubling time with any detectable and pelvic confined disease in patients with biochemically recurrent prostate cancer. MATERIALS AND METHODS: Data from 108 patients with biochemically recurrent prostate cancer after radical prostatectomy who underwent prostate specific membrane antigen targeted (18)F-DCFPyL positron emission tomography/computerized tomography were analyzed. Data were collected on positive positron emission tomography findings as well as pelvic confined disease. Associations between Gleason sum, prostate specific antigen and prostate specific antigen doubling time were retrospectively explored. RESULTS: Serum prostate specific antigen was associated with positive prostate specific membrane antigen targeted imaging as continuous (OR 3.08, 95% CI 1.60–7.95, p=0.005) and categorical values (ie prostate specific antigen greater than 2.0 to 5.0 vs 0.5 ng/ml or less, OR 16.92, 95% CI 3.13–315.81, p=0.008). No relationship between Gleason sum or prostate specific antigen doubling time with overall positive imaging was observed. Patients with a prostate specific antigen greater than 2.0 to 5.0 ng/ml were significantly less likely to be diagnosed with pelvic confined disease compared with the 0.5 ng/ml or less subgroup (OR 0.21, 95% CI 0.06–0.69, p=0.013). A prostate specific antigen doubling time of 9 months or more (OR 4.20, 95% CI 1.57–11.89, p=0.005) or prostate specific antigen doubling time of 12 months or more (OR 3.03, 95% CI 1.12–8.76, p=0.033) was significantly associated with pelvic confined disease. No relationship between Gleason sum and pelvic confined disease was observed. CONCLUSIONS: Absolute prostate specific antigen was positively associated with the presence of findings on prostate specific membrane antigen targeted imaging and negatively associated with pelvic confined disease. Prostate specific antigen doubling time did not predict for overall disease detection, but long prostate specific antigen doubling times were associated with pelvic confined prostate cancer.

INTRODUCTION AND OBJECTIVE:Several PSMA-targeted imaging agents are currently in development for initial staging of men at risk of harboring metastatic prostate cancer (PCa) not detected by convent...

Transthyretin cardiac amyloidosis (ATTR and ATTRv) is an underrecognized cause of heart failure that results from myocardial deposition of misfolded protein (TTR or prealbumin). The diagnosis can be confirmed by uptake of 99m Tc-pyrophosphate ( 99m Tc-PYP) in the heart with serologic studies to rule out light chain disease. We present the case of a 70-year-old woman who underwent a 99m Tc-PYP scan. The patient had a large right-sided pleural effusion that lowered counts in the right chest on planar imaging, interfered with ratio-based grading of PYP uptake, and highlighted the importance of obtaining SPECT/CT for problem-solving in cases where uptake ratios may be spurious.

We present the case of a 60-year-old man with medullary thyroid carcinoma and hepatic, osseous, and lymph node metastases who underwent peptide receptor radionuclide therapy with 177Lu-DOTATOC. After 2 cycles, 68Ga-DOTATOC PET/CT revealed multiple nonavid lesions. To assess whether the patient would be eligible for prostate-specific membrane antigen (PSMA)-targeted radioligand therapy, a PSMA PET/CT was conducted. PSMA PET/CT identified increased PSMA expression in both 68Ga-DOTATOC-avid and nonavid lesions. As such, dual-radiotracer PET/CT may allow for insights into the complexities of tumor heterogeneity in patients with medullary thyroid carcinoma, which may pave the way for subsequent therapeutic algorithms.

Three-dimensional (3D) visualizations of computed tomography (CT) data have found use in the display of complex anatomy and pathology. A new method of 3D CT image creation known as cinematic rendering (CR) makes use of a global lighting model to produce photorealistic images. Cinematic rendering images contain high levels of detail with shadowing and depth that are not available from traditional 3D CT techniques. As yet, the role of CR in evaluating colonic pathology has not been investigated. However, given the breadth of pathologic processes that affect the colon, including inflammatory bowel disease, diverticulitis, neoplastic conditions, herniation, and gastrointestinal bleeding, we undertook a survey of recent cases at our institution to demonstrate colon pathology as visualized with CR. The following review discusses the role of 3D CT visualizations for colonic pathology with an emphasis on CR example images.

Introduction:Improved diagnostics are needed to better inform the treatment of men with biochemically recurrent (BCR) prostate cancer (PCa). 18F-DCFPyL is a novel PET agent that selectively binds w...

INTRODUCTION AND OBJECTIVE:Current imaging modalities are suboptimal for the initial staging of men at risk of harboring occult metastatic prostate cancer (PCa) because of the low positive and nega...

Purpose of review To explore the current state of using prostate-specific membrane antigen (PSMA)-targeted PET imaging to aid in the diagnosis of clinically significant prostate cancer. Recent findings Prostate-specific antigen screening remains controversial, as it is associated with the underdetection of clinically significant prostate cancer as well as the overdetection and subsequent overtreatment of clinically insignificant disease. A diagnostic test that can accurately assess the presence of clinically significant prostate cancer and avoid detection of low-risk tumors is needed. Multiparametric magnetic resonance imaging (mpMRI) can aid in the detection of clinically significant prostate cancer and can be used with fusion-based biopsy platforms to target biopsies to specific lesions. However, there are several limitations of mpMRI including a modest negative predictive value for high-grade cancer. PSMA-targeted PET imaging has shown promise as a noninvasive test to aid in the detection of clinically significant prostate cancer while providing anatomical information to guide targeted biopsies. PSMA-targeted PET in combination with mpMRI offers a higher degree of diagnostic accuracy for imaging localized prostate cancer than either modality alone. Summary PSMA-targeted PET imaging can aid in the identification of men with clinically significant prostate cancer. Further research is needed to determine the full potential of PSMA-targeted imaging in both the detection and treatment of localized prostate cancer.

Purpose of review To explore the role of molecular imaging in the characterization of renal masses. Recent findings Incidentally detected renal masses exhibit variable malignant potential related to their underlying histology. Patients presenting with a renal mass should undergo individual risk stratification including characterization of their tumor histology. At the present time, anatomical imaging techniques are unable to reliably distinguish between the various renal tumor subtypes. Although renal mass biopsy is helpful in this regard, there are limitations of this procedure. Molecular imaging offers a noninvasive means of determining the histology of renal tumors. Imaging tests that have shown particular promise for this application include I-girentuximab PET/CT for diagnosing clear cell renal cell carcinoma and Tc-sestamibi SPECT/CT for diagnosing renal oncocytomas and hybrid oncocytic/chromophobe tumors. Summary Molecular imaging offers a noninvasive means of determining the histology of renal tumors thereby aiding in the risk stratification of patients presenting with a renal mass. Future work aims to develop a molecular imaging test that employs dual radiotracers allowing for the more precise characterization of renal tumors in a convenient single radiologic study.

Purpose: We prospectively evaluated the diagnostic performance of prostate specific membrane antigen targeted 18F-DCFPyL positron emission tomography/computerized tomography in the preoperative staging of men at high risk for harboring metastatic prostate cancer despite a negative conventional staging evaluation.Materials and Methods: Men with clinically localized high or very high risk prostate cancer were imaged with 18F-DCFPyL positron emission tomography/computerized tomography before undergoing radical prostatectomy with standardized pelvic lymph node dissection. The scans were interpreted by 2 blinded nuclear medicine readers and assessed for interreader variability as well as diagnostic accuracy for pelvic lymph node staging. Surgical pathology served as the reference standard to which 18F-DCFPyL scan findings were compared.Results: A total of 25 men contributed analyzable data to this study. Seven of these patients (28%) were found to have 1 or more positive lymph nodes on surgical pathology. Site...

Recently, a novel 3-dimensional visualization methodology for volumetric computed tomography data has become available. This method, known as cinematic rendering, uses an advanced lighting model to create photorealistic images from standard computed tomography acquisition data composed of isotropic voxels. We have observed that cinematic rendering visualizations in which patients have been administered dense, positive oral contrast do not have any substantive visual artifacts and can be used to demonstrate bowel pathology to advantage (ie, "virtual fluoroscopy"). In this technical note, we describe our acquisition and visualization parameters, and we also include demonstrative examples.

The aim of this review is to discuss how novel imaging modalities and molecular markers are shaping the definition of oligometastatic prostate cancer.To effectively classify a patient as having oligometastatic prostate cancer, diagnostic tests must be sensitive enough to detect subtle sites of metastatic disease. Conventional imaging modalities can readily detect widespread polymetastatic disease but do not have the sensitivity necessary to reliably classify patients as oligometastatic. Molecular imaging using both metabolic- and molecularly-targeted radiotracers has demonstrated great promise in aiding in our ability to define the oligometastatic state. Perhaps the most promising data to date have been generated with radiotracers targeting prostate-specific membrane antigen. In addition, early studies are beginning to define biologic markers in the oligometastatic state that may be indicative of disease with minimal metastatic potential.Recent developments in molecular imaging have allowed for improved detection of metastatic prostate cancer allowing for more accurate staging of patients with oligometastatic disease. Future development of biologic markers may assist in defining the oligometastatic state and determining prognosis.

PET imaging using radiotracers that target prostate-specific membrane antigen (PSMA) are increasingly being used in the evaluation of men with prostate cancer (PCa). It is therefore of increasing importance for imaging specialists to recognize potential pitfalls of this novel imaging technique. In this report, we describe a series of benign elastofibroma dorsi with uptake of the PSMA-targeted PET radiotracer F-DCFPyL.We retrospectively analyzed the imaging data of 75 men with PCa who were consecutively imaged with F-DCFPyL PET/CT. Acquired images were reviewed for the presence of radiotracer uptake in the region of the scapular tip adjacent to the chest wall. Only those lesions with discrete radiotracer uptake corresponding to an area on CT with the characteristic appearance of an elastofibroma were considered positive.In total, 18/75 (24.0%) patients had evidence of at least one elastofibroma dorsi on F-DCFPyL PET/CT. Eight (44.4%) of these patients had unilateral lesions, all of which were right sided. Detected lesions had a median maximal diameter of 2.3 cm (range: 1.3-8.4 cm) and a median perpendicular thickness to the chest wall of 0.9 cm (range: 0.6-2.5 cm). The median maximum standardized uptake value of detected lesions was 1.4 (range: 1.1-2.4) and the median maximum standardized uptake value corrected to lean body mass was 1.1 (range: 0.8-1.7).This study is the first to report uptake of a PSMA-targeted PET radiotracer in elastofibroma dorsi. Radiotracer uptake in these benign lesions should not be falsely mistaken as sites of metastatic PCa.

Recent PET imaging of glioblastoma multiforme and other high-grade gliomas using prostate-specific membrane antigen (PSMA)-targeted small-molecule radiotracers suggests a role for these agents in diagnostic imaging of recurrent/residual tumor and that PSMA-targeted endoradiotherapies may provide a new approach to therapy for patients with these difficult-to-treat tumors. We present a case of cerebral radionecrosis demonstrating PSMA-targeted radiotracer uptake. Our findings may represent a potential pitfall and limitation to the diagnostic application of PSMA-targeted agents for high-grade gliomas.

INTRODUCTION AND OBJECTIVES:Prostate-specific membrane antigen (PSMA) is a transmembrane protein that is overexpressed by prostate cancer (PCa) cells and can be targeted using the novel PET radiotr...

Objective A series of renal hybrid oncocytic/chromophobe tumors (HOCTs) was retrospectively assessed for morphologic features and enhancement characteristics by computed tomography (CT). Materials (subjects) and methods Nine patients with pathologically proven HOCTs were identified. These patients harbored a total of 12 lesions. All patients had available preoperative contrast-enhanced CT examinations, although a proportion of the studies had been carried out at outside institutions. The morphologic characteristics and enhancement patterns of each tumor were evaluated systematically. Results Seventy-eight percent of the patients were men, with a mean age of 62 years. None of the patients had evidence of metastatic disease at the time of surgery. Mean tumor diameter was 4.4 cm. All the lesions were solid and well circumscribed. Calcifications were not seen in any of these masses. Thirty-three percent of the tumors demonstrated a central stellate hypodensity pattern, whereas a further 42% of the tumors demonstrated a heterogenous appearance. Mean attenuation values were 25.7 HU (noncontrast), 77.4 HU (arterial), 124.8 HU (venous), and 76.8 HU (delayed). Tumor-to-cortex ratios for the 2 enhanced phases (arterial and venous) were 0.56 and 0.79, respectively. Conclusions A series of HOCTs were found on CT to have 2 distinct patterns-a heterogenous enhancement pattern and an "oncocytoma-like" pattern with a central stellate hypodensity. Although the prospective diagnosis of HOCTs on the basis of CT findings is unlikely, an awareness of the existence of these lesions is important as new means of characterizing renal masses on imaging arise.

High-grade gliomas (World Health Organization grade III–IV) are highly lethal primary brain tumors. Imaging modalities, including MRI and FDG PET, provide a limited ability to differentiate treatment effects (such as radiation necrosis) from recurrent or residual tumor. As the first step in validating the applicability of prostate-specific membrane antigen (PSMA)– targeted imaging in high-grade gliomas, we evaluated the ability of the PSMA-targeted small molecule [18F]DCFPyL (2-(3-(1carboxy-5-(6-[18F] fluoro-pyridine-3-carbonyl)-amino]-pentyl)-ureido)-pentanedioic acid) to image high-grade gliomas in a series of 3 prospectively recruited patients. We found [18F]DCFPyL binds PSMA in the neovasculature of glioblastoma multiforme and tumor cells of anaplastic astrocytoma.

The novel PET probe 2-deoxy-2-(18)F-fluoro-D-sorbitol ((18)F-FDS) has demonstrated favorable renal kinetics in animals. We aimed to elucidate its imaging properties in two human volunteers. (18)F-FDS was produced by a simple one-step reduction from (18)F-FDG. On dynamic renal PET, the cortex was delineated and activity gradually transited in the parenchyma, followed by radiotracer excretion. No adverse effects were reported. Given the higher spatiotemporal resolution of PET relative to conventional scintigraphy, (18)F-FDS PET offers a more thorough evaluation of human renal kinetics. Due to its simple production from (18)F-FDG, (18)F-FDS is virtually available at any PET facility with radiochemistry infrastructure.

Purpose The differentiation of oncocytoma from renal cell carcinoma (RCC) remains a challenge with currently available cross-sectional imaging techniques. As a result, a large number of patients harboring a benign oncocytoma undergo unnecessary surgical resection. In this study, we explored the utility of 99mTc-MIBI SPECT/CT for the differentiation of these tumors based on the hypothesis that the large number of mitochondria in oncocytomas would lead to increased 99mTc-MIBI uptake. Patients and Methods In total, 6 patients (3 with oncocytoma and 3 with RCC) were imaged with 99mTc-MIBI SPECT/CT. Relative quantification was performed by measuring tumor-to-normal renal parenchyma background ratios. Results All 3 oncocytomas demonstrated radiotracer uptake near or above the normal renal parenchymal uptake (range of uptake ratios, 0.85–1.78). In contrast, the 3 RCCs were profoundly photopenic relative to renal background (range of uptake ratios, 0.21–0.31). Conclusions 99mTc-MIBI SPECT/CT appears to be of value in scintigraphically distinguishing benign renal oncocytoma from RCC.

Renal cell carcinoma (RCC) is common with more than 60,000 new cases in the United States yearly. No curative therapies are available for metastatic RCC. Improved methods of imaging metastatic RCC would be of value in identifying sites of occult disease and potentially for judging response to therapy. A 58-year-old male with known metastatic clear cell RCC was imaged with both 18F-FDG and 18F-DCFPyL PET/CT. 18F-DCFPyL is a small molecule inhibitor of the prostate-specific membrane antigen (PSMA), a target known to be highly expressed on solid tumor neovasculature. Relative to 18F-FDG, 18F-DCFPyL identified more lesions and demonstrated higher tumor radiotracer uptake.

The "drooping lily" sign is identified on intravenous urography or voiding cystourethrography in patients with a duplicated renal collecting system and refers to inferolateral displacement of a functioning lower pole moiety by an obstructed upper pole collecting system. In this case, a 2-month-old girl with a prenatal diagnosis of hydronephrosis was found to have a "scintigraphic drooping lily" sign on Tc-dimercaptosuccinic acid renal scan. Evaluation with ultrasound and voiding cystourethrography confirmed a duplicated collecting system and obstructed upper pole moiety. Correlation with anatomic imaging can help avoid mistaking the scintigraphic "drooped" lower pole for an inferiorly positioned normal kidney.

A variety of sequelae of elevated calcium levels are encountered in patients with underlying primary hyperparathyroidism, including stone formation such as calculi in the urinary tract and sialoliths in the salivary glands and ducts. We present a case of a 54-year-old woman with fatigue, myalgia, and poor concentration who was found to have hypercalcemia (corrected calcium, 11.2 mg/dL) and elevated parathyroid hormone level (112 pg/mL), laboratory values consistent with primary hyperparathyroidism. She underwent evaluation with a Tc-MIBI parathyroid SPECT scan that included x-ray CT acquisitions for anatomical localization and attenuation correction.

The incidence of congenital heart disease requiring specialized care is 2.5 to 3 per 1000 live births with a prevalence of congenital heart disease of 81.4 per 10,000 live births. Total cavopulmonary or atriopulmonary connection, used for palliation of certain types of congenital heart disease, diverts flow from the vena cava or atrium directly into the pulmonary arteries. Altered anatomy in patients who have undergone this intervention may result in contrast and/or radiotracer localizing preferentially to a single lung leading to interpretation errors and redundant studies. Performing bilateral upper-extremity injections for this patient population may reduce such technical errors and redundant studies.