Search

The prostate-specific membrane antigen (PSMA) is highly expressed on most prostate cancer (PC) cells. Therefore, the targeting of PSMA has become increasingly important over the last decade. Glu-urea-based PSMA ligands used for both imaging and radioligand therapy are the mainstays of the current success. For PET imaging, both 68Ga- and 18F-labeled agents have been successfully translated to clinical applications. Mainly retrospective cohort studies have shown a high value in the setting of biochemical recurrence, with high detection rates even in the presence of low prostate-specific antigen levels. Preliminary data indicated that radioguided surgery with PSMA ligands may help to further improve patient outcomes because it facilitates the removal of small tumor deposits that are otherwise difficult to detect. For primary PC, PSMA ligand PET imaging has been shown to be superior to cross-sectional imaging for the detection of metastatic lymph nodes. In addition, it promises to also provide intraprostatic tumor localization, especially when used in combination with multiparametric MRI. Increasing numbers of studies have reported considerable changes in management resulting from PSMA ligand PET imaging for both biochemical recurrence and primary disease. The use of 177Lu-PSMA-based radioligand therapy has demonstrated a reasonable response, mainly as defined by a prostate-specific antigen response of more than 50%, comparable to other recently introduced agents. Especially given the high level of safety of 177Lu-PSMA radioligand therapy, with only minimal grade 3 and 4 toxicities reported so far, it has the potential to expand options for metastatic castration-resistant PC. This review is intended to provide a comprehensive overview of the current literature on low-molecular-weight PSMA ligands for both PET imaging and therapeutic approaches, with a focus on agents that have been clinically adopted.

Purpose This study investigates whether the addition of preoperative Tc-MIBI SPECT/CT can increase the degree of diagnostic confidence in the differentiation of benign from malignant enhancing renal masses. Patients and methods Patients were recruited as part of an institutional review board-approved prospective clinical trial. Forty-eight patients with clinical stage T1 solid renal masses who underwent a Tc-MIBI SPECT/CT before partial or radical nephrectomy were evaluated. Conventional CT and MRI, which were approximately performed within 8 weeks before Tc-MIBI, were retrospectively retrieved. Based on a 5-point scale (1 = definitely benign, 5 = definitely malignant), 2 blinded readers recorded their degree of confidence for each lesion using conventional imaging before and after reviewing the Tc-MIBI uptake ratios. Surgical pathology was considered as the reference standard. Results Additional review of Tc-MIBI SPECT/CT uptake ratios increased diagnostic confidence in the differentiation of solid renal masses in 14/48 lesions (29.2%). In 9 lesions, the addition of Tc-MIBI changed the initial confidence levels of malignancy toward benign diagnosis. Postsurgical pathology confirmed the diagnosis of benign histology (oncocytoma/hybrid oncocytic-chromophobe tumors) in 7 and chromophobe renal cell carcinoma (behave as indolent) in 2 of these lesions. Tc-MIBI increased the confidence level toward malignancy in 5 cases; all were confirmed as RCC on surgical pathology. The area under the receiver operative characteristic curve was 0.60 for conventional imaging alone and 0.85 after reviewing Tc-MIBI (P for difference = 0.03). Conclusions Preoperative Tc-MIBI SPECT/CT enhances the performance of conventional imaging, improving the characterization of benign histologies and lowering the possibility of misclassification.

The differentiation of benign and indolent renal masses from aggressive tumor histologies cannot be reliably performed by CT or MRI. Additionally, renal mass biopsy risks complications and has a nondiagnostic rate of 10% to 20%. Tc-MIBI SPECT/CT has been shown to allow for the accurate differentiation of benign renal oncocytomas and hybrid oncocytic/chormophobe tumors from other more aggressive renal tumor types. We present the case of an 84-year-old man with chronic kidney disease and an 11.2-cm renal mass. Results of his Tc-MIBI SPECT/CT allowed avoidance of a radical nephrectomy.

To estimate the proportion of oncocytic renal neoplasms diagnosed on renal mass biopsy (RMB) confirmed on surgical pathology, a systematic review of MEDLINE, Embase, and the Cochrane databases (1997 to 1 July 2016) was conducted quantifying all cases of reported oncocytic renal neoplasms on RMB suggestive of an oncocytoma. In addition, institutional data was assessed to identify additional cases. Concordance with surgical histopathology (positive predictive value [PPV]) was evaluated for patients undergoing surgery by performing a meta-analysis. In all, 10 RMB series, including institutional data, were included in the meta-analysis with 205 RMBs identifying oncocytic renal neoplasms and 46 (22.4%) proceeding to surgery. One additional study identified two neoplasms not captured by the primary RMB series for a total of 48 unique lesions included in the analysis. Surgical pathology showed oncocytoma (64.6%), chromophobe renal cell carcinoma (RCC; 12.5%), other RCC (12.5%), hybrid oncocytic/chromophobe tumour (6.3%), and other benign lesions (4.2%). PPV of oncocytoma on RMB was 67% (95% confidence interval 34-94%) with significant heterogeneity between studies (I2 = 71.8%, P < 0.01). Risk of bias was judged to be low for four of the 10 series. Confidently diagnosing a localised renal mass as a benign lesion, such as an oncocytoma, has implications for the ultimate management strategy a patient will undergo. RMB was found to be unreliable in confidently diagnosing a localised renal mass as an oncocytoma, with one in four found to be RCC on surgical pathology. Patients and physicians should be aware of the uncertainty in diagnosis when considering management strategies.

Three-dimensional representations of volumetric CT data provide a powerful means to display and perceive complex anatomy and pathology. The development of advanced, multi-slice CT scanners that could rapidly acquire isotropic data sets without significant patient respiratory or voluntary motion has allowed for the implementation of a number of 3D reconstruction methods into clinical practice. In this chapter, we will discuss the technical considerations that underlie the most common 3D reconstruction methodologies (including surface rendering, maximum intensity projection, volume rendering, and cinematic rendering), the similarities and differences between these methodologies and how this impacts the types of imaging data each methodology is most suited to evaluate, and provide examples of some of the most common clinical uses of these techniques.

Targeting the prostate-specific membrane antigen (PSMA) with 68Ga-labeled and 18F-labeled PET agents has become increasingly important in recent years. Imaging of biochemically recurrent prostate cancer has been established as a widely accepted clinical indication for PSMA ligand PET/CT in many parts of the world because of the results of multiple, primarily retrospective, studies that indicate superior detection efficacy compared with standard-of-care imaging. For high-risk primary prostate cancer, evidence is growing that this modality significantly aids in the detection of otherwise occult nodal and bone metastases. For both clinical indications in recurrent as well as in primary prostate cancer, preliminary data demonstrate a substantial impact on clinical management. Emerging data imply that intraprostatic tumor localization, therapy stratification, and treatment monitoring of advanced disease in specific clinical situations might become future indications. Current criteria for image reporting of PSMA ligand PET are evolving given the expanding body of literature on physiologic and pathologic uptake patterns and pitfalls. This article intends to give an educational overview on the current status of PSMA ligand PET imaging, including imaging procedure and interpretation, clinical indications, diagnostic potential, and impact on treatment planning.

65-year-old woman with recurrent bouts of severe pancreatitis was status post surgical intervention.

70-year-old man was evaluated with secretin-stimulated magnetic resonance cholangiopancreatography (MRCP).

Rationale and Objectives To create novel radiology key image software that is easy to use for novice users, incorporates elements adapted from social networking Web sites, facilitates resident and fellow education, and can serve as the engine for departmental sharing of interesting cases and follow-up studies. Materials and Methods Using open-source programming languages and software, radiology key image software (the key image and case log application, KICLA) was developed. This system uses a lightweight interface with the institutional picture archiving and communications systems and enables the storage of key images, image series, and cine clips. It was designed to operate with minimal disruption to the radiologists' daily workflow. Many features of the user interface have been inspired by social networking Web sites, including image organization into private or public folders, flexible sharing with other users, and integration of departmental teaching files into the system. We also review the performance, usage, and acceptance of this novel system. Results KICLA was implemented at our institution and achieved widespread popularity among radiologists. A large number of key images have been transmitted to the system since it became available. After this early experience period, the most commonly encountered radiologic modalities are represented. A survey distributed to users revealed that most of the respondents found the system easy to use (89%) and fast at allowing them to record interesting cases (100%). Hundred percent of respondents also stated that they would recommend a system such as KICLA to their colleagues. Conclusions The system described herein represents a significant upgrade to the Digital Imaging and Communications in Medicine teaching file paradigm with efforts made to maximize its ease of use and inclusion of characteristics inspired by social networking Web sites that allow the system additional functionality such as individual case logging.

Musculoskeletal infections, particularly those in regions of complex anatomy and at postoperative sites, can be difficult to evaluate clinically, yet accurate diagnosis is essential to treat these infections promptly and correctly. Although anatomical imaging modalities are commonly used to diagnose musculoskeletal infections, the application of functional imaging through nuclear medicine techniques has long played a unique and important role in the evaluation of patients with suspected infections. In addition to the standard nuclear medicine single-photon emitting radiotracers traditionally used by nuclear medicine for planar and single-photon emission computed tomography infection imaging, in recent years we have seen a growth in the application of fluorodeoxyglucose (FDG) positron emission tomography (PET) and PET/CT applied to the detection and diagnosis of infection. In this review, we discuss the most common clinical scenarios in which musculoskeletal infection is suspected and for which FDG PET has been studied, in spinal, diabetic foot, and periprosthetic infections. We also highlight recent advances in new non-FDG PET radiotracers that may in the future enable better specificity for and characterization of musculoskeletal infections.

The purpose of this study was to evaluate 18F-FDG PET/CT scanning as an early predictor of response to immune checkpoint inhibitors (ICIs) in patients with advanced melanoma. Methods: Twenty patients with advanced melanoma receiving ICI prospectively underwent 18F-FDG PET/CT at 3 scan intervals: before treatment initiation (SCAN-1), at days 21–28 (SCAN-2), and at 4 mo (SCAN-3). This study was approved by the institutional review board, and informed consent was received from all patients who were enrolled between April 2012 and December 2013. Tumor response at each posttreatment time point was assessed according to RECIST 1.1, immune-related response criteria, PERCIST (PERCIST 1.0), and European Organization for Research and Treatment of Cancer (EORTC) criteria. Performance characteristics of each metric to predict best overall response (BOR) at ≥ 4 mo were assessed. Results: Twenty evaluable patients were treated with ipilimumab (n = 16), BMS-936559 (n = 3), or nivolumab (n = 1). BOR at ≥ 4 mo included complete response (n = 2), partial response (n = 2), stable disease (n = 1), and progressive disease (n = 15). Response evaluations at SCAN-2 using RECIST 1.1, immune-related response criteria, PERCIST, and EORTC criteria demonstrated accuracies of 75%, 70%, 70%, and 65%, respectively, to predict BOR at ≥ 4 mo. Interestingly, the optimal PERCIST and EORTC threshold values at SCAN-2 to predict BOR were >15.5% and >14.7%, respectively. By combining anatomic and functional imaging data collected at SCAN-2, we developed criteria to predict eventual response to ICI with 100% sensitivity, 93% specificity, and 95% accuracy. Conclusion: Combining functional and anatomic imaging parameters from 18F-FDG PET/CT scans performed early in ICI appears predictive for eventual response in patients with advanced melanoma. These findings require validation in larger cohorts.

Cauda equina syndrome (CES) is an uncommon entity that may be caused by a variety of conditions. It refers to dysfunction of the ventral, dorsal, sacral, and coccygeal nerve roots in the region of the filum terminale. We present a case of a 32-year-old woman with a history of BRCA1-positive metastatic breast cancer who complained of lower extremity muscle weakness increasing over a 2-week period and decreased sensation of the lower extremities accompanied by severe constipation and suspected urinary retention with overflow incontinence. The patient underwent whole-body F-FDG PET/CT and MRI of the spine with and without gadolinium-based contrast.

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.

e16572 Background: Previous work has shown that the degree of expression of prostate-specific membrane antigen (PSMA) correlates with prostate cancer (PCa) grade and stage. We evaluated the additive value of a deep learning algorithm (PSMA-AI) of a PSMA-targeted small molecule SPECT/CT imaging agent (99mTc-MIP-1404) to identify men with low risk PCa who are potential active surveillance candidates. Methods: A secondary analysis of a phase III trial (NCT02615067) of men with PCa who underwent 99mTc-MIP-1404 SPECT/CT was conducted. Patients with a biopsy Gleason score (GS) of ≤6, clinical stage ≤T2, and prostate specific antigen (PSA) < 10 ng/mL who underwent radical prostatectomy (RP) following SPECT/CT were included in the present analysis. SPECT/CT images were retrospectively analyzed by PSMA-AI, which was developed and locked prior to analysis. PSMA-AI calculated the uptake of 99mTc-MIP-1404 against the background reference (TBR). The automated TBR of 14 was used as a threshold for PSMA-AI calls of positive disease. Multivariable logistic regression analysis was used to develop a base model for identifying men with occult GS ≥7 PCa in the RP specimen. This model included PSA density, % positive biopsy cores, and clinical stage. The diagnostic performance of this model was then compared to a second model that incorporated PSMA-AI calls. Results: In total, 87 patients enrolled in the original trial contributed to the analysis. The base model indicated that PSA density and % positive cores were significantly associated with occult GS ≥7 PCa (p < 0.05), but clinical stage was not (p = 0.23). The predictive ability of the model resulted in an area under the curve (AUC) of 0.73. Upon adding PSMA-AI calls, the AUC increased to 0.77. PSMA-AI calls (p = 0.045), pre-surgery PSA density (0.019) and % positive core (p < 0.004) remained statistically significant. PSMA-AI calls increased the positive predictive value from 70% to 77% and the negative predictive value from 57% to 74%. Conclusions: The addition of PSMA-AI calls demonstrated a significant improvement over known predictors for identifying men with occult GS ≥7 PCa, who are inappropriate candidates for active surveillance. Clinical trial information: NCT02615067.

TPS5093 Background: Early and accurate detection of recurrent or metastatic prostate cancer remains an unmet diagnostic need for patient management. While agents for positron emission tomography (PET), such as 11C-choline and 18F-fluciclovine, have emerged as options for imaging recurrent prostate cancer, these agents are not specific for the disease. 18F-DCFPyL is a novel, low-molecular weight, PET radiopharmaceutical that binds selectively to prostate-specific membrane antigen with high affinity. In prior studies, 18F-DCFPyL PET/CT has shown reliable diagnostic performance in detecting metastatic or recurrent prostate cancer (Rowe Mol Imaging Biol 2016 18:411-19; Gorin J Urol 2018 1999:126-32). Methods: CONDOR is a phase 3, multicenter, open-label study designed to assess the diagnostic performance and clinical impact of 18F-DCFPyL PET/CT in men with suspected recurrent or metastatic prostate cancer. Approximately 200 patients are planned to be enrolled across 15 centers in the United States and Canada. Eligible patients ≥18 years of age must have histologically confirmed prostate adenocarcinoma, have rising PSA after definitive therapy, and negative or equivocal conventional imaging. A single 9 mCi (333 MBq) dose of 18F-DCFPyL is administered, followed by whole body PET/CT scan 1 hour later. The primary objective is to assess the correct localization rate (percentage of patients with a one-to-one correspondence between localization of at least one lesion identified on 18F-DCFPyL PET/CT and the composite truth standard, defined as either evaluable histopathology, informative correlative imaging, or PSA response after radiation therapy). Additional study objectives include safety and tolerability of 18F-DCFPyL, impact on intended treatment plans, detection rates and PPV of 18F-DCFPyL by region, and detection rates by baseline PSA. 18F-DCFPyL PET/CT results are centrally reviewed by independent readers blinded to all clinical and other imaging information. As of February 9, 2019, a total of 36 patients have been dosed in the study. Clinical trial information: NCT03739684.

5012 Background: Accurate detection of prostate cancer is imperative to patient management, yet standard imaging methods perform poorly in accurately detecting mPC. 18F-DCFPyL is a novel PET imaging agent that selectively binds to prostate-specific membrane antigen, a recognized target for prostate cancer. OSPREY was a prospective, multicenter study in pts with either newly diagnosed high-risk prostate cancer (cohort A), or known or suspected mPC (cohort B). Here we focus on Cohort B. Methods: 117 men planned for biopsy of recurrent or mPC received 18F-DCFPyL. Pts underwent image-guided biopsy. Sensitivity, positive predictive value (PPV), and safety of 18F-DCFPyL PET/CT were the key endpoints for Cohort B. 18F-DCFPyL PET/CT scans were evaluated by three independent, blinded central readers; and results were compared to histopathology as the truth standard. Results: The sensitivity and PPV of 18F-DCFPyL PET/CT as compared to histopathology ranged from 92.9-98.6% (lower bound of 95% CI: 84.0-91.6%) and 81.2-87.8%, respectively. Diagnostic performance by anatomic location showed high sensitivity and high PPV in all sites of disease (Table). Only two (1.7%) cohort B pts experienced ≥1 drug-related AE (dysgeusia and generalized rash), both were mild (Grade 1) in severity. Conclusions: 18F-DCFPyL PET/CT was well tolerated and demonstrated high sensitivity and PPV in accurately detecting nodal, bone, and visceral/soft tissue metastases. A positive 18F-DCFPyL PET/CT scan is highly likely to represent pathologically proven distant disease, demonstrating the potential of 18F-DCFPyL as a PET imaging agent to favorably influence treatment planning. Clinical trial information: NCT02981368. [Table: see text]

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.

Prostate-specific membrane antigen (PSMA) is expressed by prostate cancer cells as well as endothelial cells within the neovasculature of a number of malignancies including renal cell carcinoma (RCC). PET radiotracers that target PSMA have shown great promise for imaging RCC. Agents that target PSMA also have the potential to be used as therapeutics in patients with this malignancy.

An increasingly robust body of evidence indicates that multiparametric MRI (mpMRI) prior to prostate biopsy can improve the detection of clinically significant prostate cancer while avoiding unnecessary biopsies. As a result, the use of mpMRI and biopsy platforms that allow for the real-time fusion of mpMRI and transrectal ultrasound images is now routinely used in clinical practice. On the horizon, molecular imaging offers the promise of improved sensitivity relative to mpMRI and early data would suggest that the combination of mpMRI and positron emission tomography using radiotracers targeting prostate-specific membrane antigen provide a more accurate assessment than either modality alone. In this review, we examine the current role of imaging to aid in the initial diagnosis of prostate cancer.

Diagnosis of autoimmune encephalitis presents some challenges in the clinical setting because of varied clinical presentations and delay in obtaining antibody panel results. We examined the role of neuroimaging in the setting of autoimmune encephalitides, comparing the utility of (18)F-FDG PET/CT versus conventional brain imaging with MRI. Methods: A retrospective study was performed assessing the positivity rate of MRI versus (18)F-FDG PET/CT during the initial workup of 23 patients proven to have antibody-positive autoimmune encephalitis. (18)F-FDG PET/CT studies were analyzed both qualitatively and semiquantitatively. Areas of cortical lobar hypo (hyper)-metabolism in the cerebrum that were 2 SDx from the mean were recorded as abnormal. Results: On visual inspection, all patients were identified as having an abnormal pattern of (18)F-FDG uptake. In semiquantitative analysis, at least 1 region of interest with metabolic change was identified in 22 of 23 (95.6%) patients using a discriminating z score of 2. Overall, (18)F-FDG PET/CT was more often abnormal during the diagnostic period than MRI (10/23, 43% of patients). The predominant finding on brain (18)F-FDG PET/CT imaging was lobar hypometabolism, being observed in 21 of 23 (91.3%) patients. Hypometabolism was most commonly observed in the parietal lobe followed by the occipital lobe. An entire subset of antibody-positive patients, anti–N-methyl-d-aspartate receptor (5 patients), had normal MRI results and abnormal (18)F-FDG PET/CT findings whereas the other subsets demonstrated a greater heterogeneity. Conclusion: Brain (18)F-FDG PET/CT may play a significant role in the initial evaluation of patients with clinically suspected antibody-mediated autoimmune encephalitis. Given that it is more often abnormal when compared with MRI in the acute setting, this molecular imaging technique may be better positioned as an early biomarker of disease so that treatment may be initiated earlier, resulting in improved patient outcomes.

The purpose of this study was to assess the diagnostic performance of whole-body

OBJECTIVE Adrenal hemorrhages arise as a result of a number of conditions and may exhibit a variety of appearances on computed tomography (CT). On occasion, patients will undergo adrenalectomy for treatment of a presumptive adrenal neoplasm that on surgical pathology is identified as an adrenal hemorrhage. We evaluated the CT appearance of surgically resected adrenal masses from our institution over a period of 15 years that ultimately proved to be adrenal hematomas. METHODS A surgical pathology archive was queried for all cases of adrenal hemorrhage. Only cases with a corresponding diagnostic CT were included. Cases were excluded if an underlying adrenal mass was present. For the remaining cases, the CT appearances were evaluated by 2 radiologists quantitatively and qualitatively. RESULTS Our search yielded 18 cases of adrenal hemorrhage, of which 5 cases had corresponding CT and no underlying secondary process within the adrenal. All of the adrenal hematomas in this series demonstrated an ovoid morphology and were well defined, with an average maximum diameter of 8.9 cm and highly variable attenuation on noncontrast CT (average attenuation range, 13.1-44.0 Hounsfield units [HU]). Four of the 5 lesions had degrees of peripheral enhancement that was either thin and somewhat uniform or heterogeneous and irregular. None of the lesions demonstrated invasion of the periadrenal fat or adjacent organs. CONCLUSIONS Adrenal hematomas with a mass-like configuration offer a potential diagnostic dilemma for radiologists and surgeons. Although it is rare that an adrenal hemorrhage is surgically resected, awareness of the potential appearances of these lesions is important to spare patients from unnecessarily aggressive surgery.

Subcutaneous F-FDG uptake is a common finding on PET scans, with causes including both benign and malignant conditions. Often, the pattern of uptake or the clinical indication for the PET scan will suggest the etiology. However, unusual or unexpected patterns may require careful clinical history. We report the case of a 45-year-old woman who underwent a PET/CT study for paraneoplastic syndrome evaluation and was found to have intense, extensive, bilaterally symmetric, nodular subcutaneous FDG uptake in the lower back and buttocks that was related to long-term repeated subcutaneous opioid injections.

Prostate-specific membrane antigen (PSMA) is a cell surface enzyme that is highly expressed in prostate cancer (PCa) and is currently being extensively explored as a promising target for molecular imaging in a variety of clinical contexts. Novel antibody and small-molecule PSMA radiotracers labeled with a variety of radionuclides for positron emission tomography (PET) imaging applications have been developed and explored in recent studies.A great deal of progress has been made in defining the clinical utility of this class of PET agents through predominantly small and retrospective clinical studies. The most compelling data to date has been in the setting of biochemically recurrent PCa, where PSMA-targeted radiotracers have been found to be superior to conventional imaging and other molecular imaging agents for the detection of locally recurrent and metastatic PCa.Early data, however, suggest that initial lymph node staging before definitive therapy in high-risk primary PCa patients may be limited, although intraoperative guidance may still hold promise. Other examples of potential promising applications for PSMA PET imaging include non-invasive characterization of primary PCa, staging and treatment planning for PSMA-targeted radiotherapeutics, and guidance of focal therapy for oligometastatic disease.However, all of these indications and applications for PCa PSMA PET imaging are still lacking and require large, prospective, systematic clinical trials for validation. Such validation trials are needed and hopefully will be forthcoming as the fields of molecular imaging, urology, radiation oncology and medical oncology continue to define and refine the utility of PSMA-targeted PET imaging to improve the management of PCa patients.

Radiohalogenated agents are often the first line of pursuit in the development of new radiopharmaceuticals-whether antibodies, peptides, or small molecules-because of their ease of synthesis, lack of substantial steric perturbation of the original affinity agent (in some cases, providing enhanced affinity), and capacity to be transformed into therapeutics (in some cases, with a mere switch of an isotope). They often provide proof of a principle before optimization for pharmacokinetics or generation of radiometallated agents, when the latter are necessary. In particular, (18)F has been well integrated into normal clinical work flow in the form of (18)F-FDG for oncologic imaging, with reliable daily production and distribution to sites for immediate use, without the need for on-site preparation. Here we discuss radiohalogenated versions of imaging and therapeutic agents targeting the prostate-specific membrane antigen (PSMA); these were among the first such agents to be synthesized and used clinically. PSMA is highly expressed on prostate cancer epithelial cells and is currently being extensively investigated around the world as a target for imaging and therapy of prostate cancer. Additionally, the presence of PSMA on nonprostate tumor neovasculature has opened the possibility of PSMA-targeted molecules as generalizable cancer imaging and therapy agents. We focus on (18)F-labeled agents for PET, as they begin to redefine-along with the corresponding (68)Ga-labeled agents discussed elsewhere in this supplement to The Journal of Nuclear Medicine-the management of prostate cancer across a variety of clinical contexts.

Accurate assessment of kidney function plays an essential role for optimal clinical decision making in a variety of diseases. The major intrinsic advantages of PET are superior spatial and temporal resolutions for quantitative tomographic renal imaging. 2-deoxy-2-18F-fluorodeoxysorbitol (18F-FDS) is an analog of sorbitol that is reported to be freely filtered at the renal glomerulus without reabsorption at the tubule. Furthermore, it can be synthesized via simple reduction of widely available 18F-FDG. We tested the feasibility of 18F-FDS renal PET imaging in rats. Methods: The systemic and renal distribution of 18F-FDS were determined by dynamic 35-min PET imaging (15 frames × 8 s, 26 frames × 30 s, 20 frames × 60 s) with a dedicated small-animal PET system and postmortem tissue counting in healthy rats. Distribution of coinjected 99mTc-diethylenetriaminepentaacetic acid (DTPA) was also estimated as a reference. Plasma binding and in vivo stability of 18F-FDS were determined. Results: In vivo PET imaging visualized rapid excretion of the administrated 18F-FDS from both kidneys, with minimal tracer accumulation in other organs. Initial cortical tracer uptake followed by visualization of the collecting system could be observed with high contrast. Split-function renography curves were successfully obtained in healthy rats (the time of maximal concentration [Tmax] right [R] = 2.8 ± 1.2 min, Tmax left [L] = 2.9 ± 1.5 min, the time of half maximal concentration [T1/2max] R = 8.8 ± 3.7 min, T1/2max L = 11.1 ± 4.9 min). Postmortem tissue counting of 18F-FDS confirmed the high kidney extraction (kidney activities at 10, 30, and 60 min after tracer injection [percentage injected dose per gram]: 1.8 ± 0.7, 1.2 ± 0.1, and 0.5 ± 0.2, respectively) in a degree comparable to 99mTc-DTPA (2.5 ± 1.0, 1.5 ± 0.2, and 0.8 ± 0.3, respectively). Plasma protein binding of 18F-FDS was low (

An ever-expanding body of biological, genetic, and clinical evidence has brought to light the presence of the oligometastatic state of cancer, which is considered between localized disease and widespread metastases. Indeed, in some patients with oligometastatic disease, curative therapy is possible.For select cancer histologies, aggressive focal therapy of oligometastatic lesions is already the clinical standard of care (i.e. colorectal cancer and sarcomas), while for other tumor types the evidence is still emerging (i.e. prostate, breast, etc.). It is increasingly important, therefore, for the radiologist interpreting oncology patients' staging or restaging examinations to be aware of those diseases for which targeted therapy of oligometastases may be undertaken to effectively guide such management. The improved imaging resolution provided by technological advances promise to aid in the detection of subtle sites of disease to ensure the identification of patients with oligometastases amenable to targeted treatment.

We present the case of a 79-year-old man with an elevated postprostatectomy prostate-specific antigen level who was sequentially imaged with positron emission tomography/computed tomography (PET/CT) using 18F-fluciclovine followed by PSMA-targeted 18F-DCFPyL. Although both imaging tests successfully identified the same pelvic recurrence, each radiotracer had its relative merits. This case highlights the differences between these two PET radiotracers, which are increasingly being used to image men with recurrent prostate cancer.

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.

[No abstract available]