Positron emission tomography and positron emission tomography/computerized tomography of urological malignancies: an update review

The impact of 18F-fluorodeoxyglucose PET/computed tomography on clinical staging in bladder cancer

AIM

To determine the impact of 18F-FDG PET/computed tomography (CT) on clinical staging in bladder cancer with comparison to conventional CT and MRI.

METHODS

A total of 142 patients who underwent 18F-FDG PET/CT imaging with a diagnosis of bladder cancer between 1 June 2019 and 31 December 2020 were screened retrospectively. Seventy patients who underwent diagnostic CT or MRI within 2 months before or after PET/CT were included in the study. The N and M stages determined by CT, MRI and PET/CT according to the eighth version of the TNM staging system were recorded. T-test was used to determine the levels of significant difference, and univariate logistic regression analysis was used to evaluate the impact of the T stage on nodal up-staging.

RESULTS

According to the PET/CT, the N stage increased in 19 patients (27.14%) and decreased in seven patients (10%). Likewise, the M stage increased in 16 patients (22.86%) and decreased in seven patients (10%). The N stage determined by PET/CT was confirmed by pathologic examination in all cases in which the two modalities were inconsistent. In muscle-invasive cases, the rate of increase in the N stage after PET/CT (36.95%) was found to be significantly higher than in that of cases without invasion (8.33%) (P = 0.011). Increasing T stage was associated with an increase in the N stage after PET/CT (odds ratio: 2.33, 95% confidence interval: 1.02-5.28, P = 0.042).

CONCLUSION

18F-FDG PET/CT can potentially change the clinical stage determined by CT and MRI when used for staging in bladder cancer, and can lead to nodal up-staging particularly in cases with muscle-invasive bladder cancer.

Emerging methods for prostate cancer imaging: evaluating cancer structure and metabolic alterations more clearly

Imaging plays a fundamental role in all aspects of the cancer management pathway. However, conventional imaging techniques are largely reliant on morphological and size descriptors that have well-known limitations, particularly when considering targeted-therapy response monitoring. Thus, new imaging methods have been developed to characterise cancer and are now routinely implemented, such as diffusion-weighted imaging, dynamic contrast enhancement, positron emission technology (PET) and magnetic resonance spectroscopy. However, despite the improvement these techniques have enabled, limitations still remain. Novel imaging methods are now emerging, intent on further interrogating cancers. These techniques are at different stages of maturity along the biomarker pathway and aim to further evaluate the cancer microstructure (vascular, extracellular and restricted diffusion for cytometry in tumours) magnetic resonance imaging (MRI), luminal water fraction imaging] as well as the metabolic alterations associated with cancers (novel PET tracers, hyperpolarised MRI). Finally, the use of machine learning has shown powerful potential applications. By using prostate cancer as an exemplar, this Review aims to showcase these potentially potent imaging techniques and what stage we are at in their application to conventional clinical practice.

Urothelial cell carcinoma presenting with rapid visual deterioration, a case of rare brain metastases with unique clinical presentation

BACKGROUND

Urothelial cell carcinoma (UCC), the most common cancer of the urinary system, rarely metastasizes to the brain. 1-3 More rare still is the subset of patients with urothelial carcinoma brain metastases whose UCC primary is first diagnosed at the same time as their CNS metastatic disease, with oncologic workup prompted by CNS clinical manifestations.4 Paraneoplastic optic neuropathy (PON) is likewise a rare clinical entity, which has not yet been described in association with UCC brain metastases.

CASE DESCRIPTION

Herein, we present the sentinel case of UCC believed to be of endometrial origin in an 81 year old woman initially presenting with symptoms of fatigue, nausea, vertigo, and rapidly deteriorating vision over the course of 1 month. Visual deterioration prompted neuro imaging remarkable for multiple supratentorial and infratentorial metastases as well as likely neoplastic inflammatory involvement of the bilateral optic nerves. The patient underwent a right temporal open brain biopsy, with pathology findings consistent with UCC. Subsequent PET scanning demonstrated a heavy burden of disease including an FDG-avid uterine mass with local and distal extension of disease including bilateral hydroureteronephrosis with obstruction of the distal ureters. The patient and her family elected to pursue home hospice without further workup or intervention.

CONCLUSIONS

While this is the first such case presented, it is possible that UCC of the uterine wall represents a particularly aggressive form of the disease more prone to presenting with CNS metastases and PON.

Imaging response assessment of immunotherapy in patients with renal cell and urothelial carcinoma

PURPOSE OF REVIEW

Recent advances in anticancer immunotherapy have revolutionized the treatment of metastatic renal cell (RCC) and urothelial carcinoma. In this review, we discuss the mechanisms of action of these new therapeutic approaches, explicate the common adverse events, and highlight different imaging-based response criteria.

RECENT FINDINGS

The recent introduction of immune-checkpoint inhibitors led to substantial advances in therapy of metastatic RCC and urothelial carcinoma. Because of the distinct effector mechanisms of these new substances, atypical response patterns such as transient enlargements of tumor lesions, appearance of new lesions after therapy, no measurable decrease in tumor size, or delayed responses are observed in medical imaging studies. This indicates that the established imaging-based response assessment according to the Response Evaluation Criteria in Solid Tumors (RECIST) guidelines has shortcomings to comprehensively evaluate treatment effects.

SUMMARY

While monitoring response to immunotherapy still relies on RECIST criteria, immune-related response criteria have been established to better address the imaging changes occurring under immunotherapy. Further studies with long-term follow-up are needed to properly identify and predict response after treatment beyond progression. Because of the expanding clinical use of immune checkpoint inhibitors, radiologists, urologist, and oncologists should be familiar with common imaging findings under this respective therapy.

Lower tract neoplasm: Update of imaging evaluation

Cancers of the lower urinary tract can arise from the bladder, urachus or urethra. Urothelial carcinoma of the bladder (UCB) is the most common of these. The presentation of bladder, urachal and urethral cancers can differ but many result in hematuria as an initial indication. The diagnosis and staging of these cancers often necessitate radiologic imaging often in the form of cross-section CT urography or MR urography. The following article reviews the specific nature of lower tract cancers and their imaging.

Updates for the radiologist in non-muscle-invasive, muscle-invasive, and metastatic bladder cancer

Urothelial bladder cancer is a common malignancy requiring a multidisciplinary approach to treatment. Significant recent advances have been made in terms of the genetic and molecular characterization of bladder cancer subtypes, and novel treatment approaches are being investigated and approved. Given the important role of imaging in the diagnosis, staging, and follow-up of this disease, it is necessary for radiologists to remain up-to-date in terms of nomenclature and standards of care. In this review, recent developments in bladder cancer characterization and treatment will be discussed, with reference to the contributions of imaging in non-muscle-invasive, muscle-invasive, and metastatic settings.

Positron emission tomography (PET) in primary prostate cancer staging and risk assessment

Prostate cancer (PCa) is one of the few neoplasms that are not well served by 18F-Fluorodeoxyglucose (FDG) positron emission tomography (PET). As a result, a number of PET tracers have been developed to target particular biological features of PCa. Such agents can be used for diagnosis, staging, identification of biochemical recurrence (BCR) and evaluation of metastatic disease. Here, we focus on primary disease and local staging. To date, magnetic resonance imaging (MRI) has proven superior to PET in the imaging of primary PCa. However, some PET agents have shown remarkable promise in staging high-risk PCa (defined as any combination of a clinical T3, a PSA score >20 ng/mL, or a Gleason score of 8–10), as well as biochemical relapse after definitive therapy and metastatic PCa. PET agents can be divided into those that interrogate tumor metabolism (¹⁸F-FDG, ¹¹C-Choline, ¹⁸F-Choline, ¹¹C-Acetate, 18F-FACBC), hormone receptors (18F-FDHT), and other targets such as prostate specific membrane antigen (PSMA) (⁶⁸Ga-PSMA, ¹⁸F-DCFBC, ¹⁸F-DCFPyl) or gastric releasing peptide (¹⁸F-GRP or ¹⁸F-Bombesin). In this review, we compare the available PCa targeted PET tracers utilized in staging of high risk tumors.

Investigation into the Biological Impact of Block Size on Cathepsin S-Degradable HPMA Copolymers

N-(2-Hydroxypropyl)methacrylamide (HPMA) copolymers have been studied as an efficient carrier for drug delivery and tumor imaging. However, as with many macromolecular platforms, the substantial accumulation of HPMA copolymer by the mononuclear phagocyte system (MPS)-associated tissues, such as the blood, liver, and spleen, has inhibited its clinical translation. Our laboratory is pursuing approaches to improve the diagnostic and radiotherapeutic effectiveness of HPMA copolymers by reducing the nontarget accumulation. Specifically, we have been investigating the use of a cathepsin S (Cat S)-cleavable peptidic linkers to degrade multiblock HPMA copolymers to increase MPS-associated tissue clearance. In this study, we further our investigation into this area by exploring the impact of copolymer block size on the biological performance of Cat S-degradable HPMA copolymers. Using a variety of in vitro and in vivo techniques, including dual labeling of the copolymer and peptide components, we investigated the constructs using HPAC pancreatic ductal adenocarcinoma models. The smaller copolymer block size (S-CMP) demonstrated significantly faster Cat S cleavage kinetics relative to the larger system (L-CMP). Confocal microscopy demonstrated that both constructs could be much more efficiently internalized by human monocyte-differentiated macrophage (hMDM) compared to HPAC cells. In the biodistribution studies, the multiblock copolymers with a smaller block size exhibited faster clearance and lower nontarget retention while still achieving good tumor targeting and retention. Based on the radioisotopic ratios, fragmentation and clearance of the copolymer constructs were higher in the liver compared to the spleen and tumor. Overall, these results indicate that block size plays an important role in the biological performance of Cat S-degradable polymeric constructs.

Metastatic renal clear cell carcinoma to the rectum, lungs, ilium, and lymph nodes: A case report

BACKGROUND

Renal cell carcinoma metastasizing to rectum is very rare, and the unusual metastatic sites should be paid attention to during the follow-up of renal cell carcinoma.

CASE SUMMARY

We describe a case of a 65-year-old male who was diagnosed with metastatic renal cell carcinoma to rectum 10 years after the right radical nephrectomy. Histopathology and immunohistochemical examinations contribute to making differential diagnosis between rectal metastasis of renal cell carcinoma and primary rectal clear cell carcinoma. Positron emission tomography-computed tomography with fluorodeoxyglucose shows hypermetabolic activity in upper rectum and other sites of metastasis at the same time.

CONCLUSION

Possibility of unusual metastatic sites of renal cell carcinoma such as rectum indeed exists, which should not be ignored in the surveillance after resection of the primary tumor.

Pictorial review of orthotopic neobladder reconstruction: indication, normal postsurgical anatomy, and complications

Radical cystectomy with urinary diversion is a common urological procedure performed for the treatment of bladder cancer. Numerous surgical procedures have been developed for urinary diversion. Over the past decade, orthotopic neobladder reconstruction has been used frequently for urinary diversion because of its advantageousness in providing patients with a good quality of life compared with other urinary diversion technique. Knowledge of the indication, surgical procedure, and postsurgical anatomy of orthotopic neobladder reconstruction is essential. While the technique has many advantages, multiple postsurgical complications may occur after reconstruction, including urine leakage, bowel obstruction and fluid collection (lymphocele, urinoma, hematoma, and abscess), neobladder rupture, vesicoureteral reflux, hydronephrosis, urinary tract infection, urinary calculi, abdominal incisional hernia, bowel obstruction, intraneobladder tumor, and tumor recurrence. Radiological imaging including multiple modalities such as intravenous urography, cystography, CT, and MRI plays an important role in the postoperative evaluation of patients with orthotopic neobladder reconstruction and is an accurate method for evaluating complications. In addition, knowledge of appearances on multimodal imaging helps clinicians to select the modality required to achieve an accurate diagnosis of each complication and avoid misdiagnosis.

Clinical Relevance of Incidental Prostatic Lesions on FDG-Positron Emission Tomography/Computerized Tomography-Should Patients Receive Further Evaluation?

PURPOSE

FDG ((18)F-fluoro-2-deoxy-D-glucose)-PET/CT (positron emission tomography)/(computerized tomography) is a widely used diagnostic tool for whole body imaging. Incidental prostatic uptake is often found on FDG-PET/CT. The objective of this study was to determine the clinical relevance of incidental prostatic uptake on FDG-PET/CT.

MATERIALS AND METHODS

We analyzed 108 consecutive male patients with bladder cancer who underwent FDG-PET/CT and subsequently radical cystoprostatectomy between May 2009 and November 2014. PET/CT scans were blindly reviewed by a dedicated nuclear medicine physician for incidental prostatic FDG uptake. If present, the maximum standardized uptake value was determined. Subsequently incidental prostatic uptake was categorized as suspect, indeterminate or nonsuspect for prostate cancer.

RESULTS

Incidental prostatic uptake was present in 43 of 108 patients (40%). Of these 43 patients 13 (30%) had occult prostate cancer in cystoprostatectomy specimens. Overall prostate cancer was found in 25 of 108 specimens (23%). If all incidental prostatic uptake was regarded as prostate cancer, the sensitivity and specificity of FDG-PET/CT for prostate cancer detection were 52% and 64%, respectively. Positive and negative predictive values were 30% and 82%, respectively. If only lesions labeled suspect or indeterminate were regarded as prostate cancer, sensitivity, specificity, and positive and negative predictive values were 32%, 76%, 29% and 79%, respectively. Categorizing indeterminate lesions as nonprostate cancer did not improve diagnostic accuracy. Gleason score did not correlate with maximum standardized uptake value or serum prostate specific antigen.

CONCLUSIONS

Incidental prostatic uptake on FDG-PET/CT has a low positive predictive value for prostate cancer. An attempt to classify lesions as suspect or nonsuspect did not increase diagnostic accuracy. Based on these results physicians should be cautious about applying invasive diagnostic methods to detect prostate cancer in case of incidental prostatic uptake on FDG-PET/CT.

Contemporary role of advanced imaging for bladder cancer staging

Optimized pretreatment staging of bladder urothelial carcinoma is essential in guiding appropriate treatment. This staging process relies heavily on tissue pathology from transurethral resection of bladder tumor as well as imaging for diagnosis of local, regional, nodal, or distant visceral spread. Accurate preoperative staging is critical for appropriate treatment decision making and patient counseling as these are based on the extent of disease involvement, largely classifying the cancer as having local, regional, or distant spread. Currently, the gold standard of transurethral resection of bladder tumor followed by computed tomography imaging with intravenous contrast provides excellent staging specificity in cases of more advanced bladder cancers with suspicion of spread; however, this often under stages patients that can lead to adverse oncologic outcomes in these patients undergoing radical cystectomy. Incorporation of novel imaging modalities including multiparametric magnetic resonance imaging and positron emission tomography imaging have shown promise in improving accuracy of staging for both local and distant disease in patients with bladder urothelial carcinoma.

PET/CT versus conventional CT for detection of lymph node metastases in patients with locally advanced bladder cancer

Background

We studied patients treated with radical cystectomy for locally advanced bladder cancer to compare the results of both preoperative positron emission tomography/computed tomography (PET/CT) and conventional CT with the findings of postoperative histopathological evaluation of lymph nodes.

Methods

Patients who had bladder cancer and were candidates for cystectomy underwent preoperative PET/CT using 18-fluorodeoxyglucose (FDG) and conventional CT. The results regarding lymph node involvement were independently evaluated by two experienced radiologists and were subsequently compared with histopathology results, the latter of which were reassessed by an experienced uropathologist (HO).

Results

There were 54 evaluable patients (mean age 68 years, 47 [85 %] males and 7 [15 %] females) with pT and pN status as follows: < pT2-14 (26 %), pT2-10 (18 %), and > pT2-30 (56 %); pN0 37 (69 %) and pN+ 17 (31 %). PET/CT showed positive lymph nodes in 12 patients (22 %), and 7 of those cases were confirmed by histopathology; the corresponding results for conventional CT were 11 (20 %) and 7 patients (13 %), respectively. PET/CT had 41 % sensitivity, 86 % specificity, 58 % PPV, and 76 % NPV, whereas the corresponding figures for conventional CT were 41 %, 89 %, 64 %, and 77 %. Additional analyses of the right and left side of the body or in specified anatomical regions gave similar results.

Conclusions

In this study, PET/CT and conventional CT had similar low sensitivity in detecting and localizing regional lymph node metastasis in bladder cancer.

FDG PET-CT for lymph node staging of bladder cancer: a prospective study of patients with extended pelvic lymphadenectomy

BACKGROUND

The purpose of this study was to evaluate the diagnostic accuracy of [(18)F] fluorodeoxyglucose (FDG) positron emission tomography-computed tomography (PET-CT) for lymph node (LN) staging of bladder cancer patients undergoing radical cystectomy (RC) with extended pelvic lymphadenectomy compared to conventional CT.

METHODS

A total of 61 patients underwent FDG PET-CT before RC and extended pelvic lymphadenectomy. A template for extended pelvic lymphadenectomy to the level of the inferior mesenteric artery was divided into 11 anatomic nodal packets. Definitive pathologic findings of resected LNs were correlated with the results of FDG PET-CT and CT alone in a patient- and nodal packet-based manner.

RESULTS

Among the 61 patients, pathological staging confirmed LN metastasis in 17 patients (27.9 %). In total, 627 LN packets (2580 LNs) were resected and histologically evaluated. The mean number of LNs removed was 42 (median 40; range 22-118). Of the 627 LN packets removed, 27 packets (4.3 %) were positive for LN metastasis based on pathologic analysis. On a patient-based analysis, FDG PET-CT and conventional CT showed a sensitivity of 47.1 and 29.4 %, respectively, specificity of 93.2 and 97.7 %, respectively, positive predictive value (PPV) of 72.7 and 78.2 %, respectively, and negative predictive value (NPV) of 82.0 and 78.2 %, respectively. On a nodal packet-based analysis, sensitivity, specificity, PPV, and NPV were 14.8, 97.8, 23.5, and 96.2 %, respectively, for PET-CT and 11.1, 98.7, 27.3, and 96.1 %, respectively, for conventional CT.

CONCLUSIONS

Combined FDG PET-CT did not improve the diagnostic accuracy of conventional CT for the detection of LN metastasis in bladder cancer patients scheduled for RC.

A case of brain and leptomeningeal metastases from urothelial carcinoma of the bladder

Brain metastases are unusual from urethelial carcinoma of bladder and particularly the occurrence of leptomeningeal metastases is extremely rare, with few cases described in the literature. We present a case of a 45-year-old man with a rare brain metastases as the first metastatic manifestation secondary to urethelial carcinoma of bladder followed by leptomeningeal metastases without any other organ involvement. Eleven months after the diagnosis of high-grade urethelial carcinoma of bladder (T2N0M0), the patient was detected having brain metastases by MRI. FDG PET/CT images for the metastatic evaluation showed no abnormal FDG uptake elsewhere in the body except the brain. Histopathology examination from brain lesion demonstrated the cerebral lesion to be a metastatic urothelial carcinoma. Two months later, the patient was diagnosed to have leptomeningeal metastases by MRI. Our patient's condition gradually worsened, and he died 3 months after the diagnosis of leptomeningeal metastases.

Prevalence and risk of cancer of incidental uptake in prostate identified by fluorine-18 fluorodeoxyglucose positron emission tomography/computed tomography

OBJECTIVE

The objective was to investigate the prevalence of incidental fluorine-18 fluorodeoxyglucose (FDG) uptake in positron emission tomography/computed tomography.

METHODS

A total of 11,239 male nonprostate disease patients were included retrospectively.

RESULTS

The prevalence of incidental prostate FDG uptake was approximately 1.8%. Among 198 incidental lesions, 100 patients had further examinations; 20 lesions were confirmed to be malignant, while 80 lesions were benign. After logistic regression analysis, age, site, and the maximum standard uptake value were the potent predictors for differentiation of malignant prostate lesions.

CONCLUSION

When focal FDG uptake in the peripheral zone of prostate is detected, especially in elderly men, further clinical evaluation is recommended.

Current approaches, challenges and future directions for monitoring treatment response in prostate cancer

Prostate cancer is the most commonly diagnosed non-cutaneous neoplasm in men in the United States and the second leading cause of cancer mortality. One in 7 men will be diagnosed with prostate cancer during their lifetime. As a result, monitoring treatment response is of vital importance. The cornerstone of current approaches in monitoring treatment response remains the prostate-specific antigen (PSA). However, with the limitations of PSA come challenges in our ability to monitor treatment success. Defining PSA response is different depending on the individual treatment rendered potentially making it difficult for those not trained in urologic oncology to understand. Furthermore, standard treatment response criteria do not apply to prostate cancer further complicating the issue of treatment response. Historically, prostate cancer has been difficult to image and no single modality has been consistently relied upon to measure treatment response. However, with newer imaging modalities and advances in our understanding and utilization of specific biomarkers, the future for monitoring treatment response in prostate cancer looks bright.

A comparative study of radiolabeled bombesin analogs for the PET imaging of prostate cancer

Radiolabeled bombesin (BBN) analogs that bind to the gastrin-releasing peptide receptor (GRPR) represent a topic of active investigation for the development of molecular probes for PET or SPECT of prostate cancer (PCa). RM1 and AMBA have been identified as the 2 most promising BBN peptides for GRPR-targeted cancer imaging and therapy. In this study, to develop a clinically translatable BBN-based PET probe, we synthesized and evaluated (18)F-AlF- (aluminum-fluoride) and (64)Cu-radiolabeled RM1 and AMBA analogs for their potential application in PET imaging of PCa.

METHODS

1,4,7-triazacyclononane, 1-glutaric acid-4,7 acetic acid (NODAGA)-conjugated RM1 and AMBA were synthesized and tested for their GRPR-binding affinities. The NODAGA-RM1 and NODAGA-AMBA probes were further radiolabeled with (64)Cu or (18)F-AlF and then evaluated in a subcutaneous PCa xenograft model (PC3) by small-animal PET imaging and biodistribution studies.

RESULTS

NODAGA-RM1 and NODAGA-AMBA can be successfully synthesized and radiolabeled with (64)Cu and (18)F-AlF. (64)Cu- and (18)F-AlF-labeled NODAGA-RM1 demonstrated excellent serum stability and tumor-imaging properties in the in vitro stability assays and in vivo imaging studies. (64)Cu-NODAGA-RM1 exhibited tumor uptake values of 3.3 ± 0.38, 3.0 ± 0.76, and 3.5 ± 1.0 percentage injected dose per gram of tissue (%ID/g) at 0.5, 1.5, and 4 h after injection, respectively. (18)F-AlF-NODAGA-RM1 exhibited tumor uptake values of 4.6 ± 1.5, 4.0 ± 0.87, and 3.9 ± 0.48 %ID/g at 0.5, 1, and 2 h, respectively.

CONCLUSION

The high-stability, efficient tumor uptake and optimal pharmacokinetic properties highlight (18)F-AlF-NODAGA-RM1 as a probe with great potential and clinical application for the PET imaging of prostate cancer.

Advances in bladder cancer imaging

The purpose of this article is to review the imaging techniques that have changed and are anticipated to change bladder cancer evaluation. The use of multidetector 64-slice computed tomography (CT) and magnetic resonance imaging (MRI) remain standard staging modalities. The development of functional imaging such as dynamic contrast-enhanced MRI, diffusion-weighted MRI and positron emission tomography (PET)-CT allows characterization of tumor physiology and potential genotypic activity, to help stratify and inform future patient management. They open up the possibility of tumor mapping and individualized treatment solutions, permitting early identification of response and allowing timely change in treatment. Further validation of these methods is required however, and at present they are used in conjunction with, rather than as an alternative to, conventional imaging techniques.

Future challenges of multimodality imaging

During the last decade, positron emission tomography/computed tomography (PET/CT) and single-photon emission computed tomography/computed tomography (SPECT/CT) have procured advances in research and clinical application of fusion imaging. The recent introduction of systems that combine PET and MRI opens new horizons for multimodality molecular imaging. These systems offer simultaneous morphologic, functional, and molecular information of a living system. Moreover, other combinations of anatomic and functional imaging modalities (for example CT and MRI or PET and optical imaging) are emerging, holding promise in basic medical research or in clinical medicine. These developments are paralleled by advances in the field of biomolecules and particles, to provide new agents useful for more than one imaging modality and to facilitate the study of the same target by different imaging devices. In the near future PET/MRI may emerge as a new powerful multimodality technique in clinical oncology, offering considerable potential for imaging applications beyond correlation of functional and anatomic images. Future developments should include the simultaneous acquisition of multifunctional data such as PET tracer uptake, MR spectroscopy, or fMRI along with high-resolution anatomic MRI.

Is further evaluation needed for incidental focal uptake in the prostate in 18-fluoro-2-deoxyglucose positron emission tomography-computed tomography images?

OBJECTIVE

The aim of this study was to investigate the frequency of secondary evaluation to detect prostate cancer that was primarily manifested as abnormal hypermetabolism detected by 18-fluoro-2-deoxyglucose (FDG) positron emission tomography-computed tomography (PET/CT). We also evaluated the association of maximum standardized uptake values (SUVmax) on PET/CT with clinicopathologic results.

MATERIALS AND METHODS

We evaluated PET/CT reports from a total of 12,037 patients to find cases with abnormal prostate hypermetabolism. Patients with known prostate cancer or a recent prostate procedure were excluded. We analyzed the frequency of secondary evaluations such as digital rectal exams (DRE), levels of serum prostate-specific antigen (PSA), and/or biopsy to confirm prostate cancer. Biopsied patients were categorized into benign and cancer groups. Clinicopathologic characteristics were compared between the groups.

RESULTS

Among 12,037 PET/CT images, 184 (1.5%) showed abnormal hypermetabolism in the prostate. Secondary evaluation was carried out in 120 patients. Biopsy was performed in 38 patients and prostate cancer was confirmed in 23 patients. The median serum PSA level was 3.2 and 49.7 ng/mL in the benign group and cancer group, respectively. The SUVmax was higher in the cancer group (5.7 ± 5.1) than in the benign group (4.8 ± 2.7), but the difference was not statistically significant (p = 0.37). In the cancer group, a high serum PSA level (≥ 20 ng/mL) was detected in 78.3% of the patients. The Gleason score was 7 in 34.7% and 8-10 in 56.5% of prostate cancer patients.

CONCLUSIONS

Hypermetabolism in the prostate was incidentally detected in 1.5% of patients, and only 65.2% of these patients underwent further evaluation (DRE and/or serum PSA levels). Among cases of incidentally detected hypermetabolism in the prostate, patients with abnormal findings (DRE and/or PSA levels) showed high positivity by biopsy, and more than two-thirds of the positive biopsies showed significant prostate cancer. Therefore, patients with hypermetabolism in the prostate should not be ignored and should be secondarily evaluated by DRE and PSA level.

Imaging in prostate cancer staging: present role and future perspectives

Despite recent improvements in detection and treatment, prostate cancer continues to be the most common malignancy and the second leading cause of cancer-related mortality. Thus, although survival rate continues to improve, prostate cancer remains a compelling medical health problem. The major goal of prostate cancer imaging in the next decade will be more accurate disease characterization through the synthesis of anatomic, functional, and molecular imaging information in order to plan the most appropriate therapeutic strategy. No consensus exists regarding the use of imaging for evaluating primary prostate cancer. However, conventional and functional imaging are expanding their role in detection and local staging and, moreover, functional imaging is becoming of great importance in oncologic management and monitoring of therapy response. This review presents a multidisciplinary perspective on the role of conventional and functional imaging methods in prostate cancer staging.

PET/CT and MRI in Bladder Cancer

Bladder Cancer (BCa) is the most common malignancy arising from the urinary tract. One of the mainstays of diagnosis, staging, and therapeutic decision-making for BCa is accurate and appropriate imaging. The ability to identify metastatic disease preoperatively is of utmost importance in determining treatment. Advances in standard cross sectional imaging techniques like Computed Tomography (CT) and Magnetic Resonance Imaging (MRI) have improved imaging of bladder cancer. Over the last decade, ¹⁸F-fluorodeoxyglucose (FDG) Positron Emission Tomography (PET) in combination with CT (¹⁸F-FDG PET/CT) has become an important non-invasive imaging modality for the preoperative staging of various malignancies. ¹⁸F-FDG PET/CT is useful for detection of metastatic disease in BCa, but the ability to detect primary bladder wall lesions remains to be elucidated. To overcome the problem with urinary excretion of ¹⁸F-FDG, new PET tracers are being tested. MRI is an accurate technique for the local staging of BCa due to its superior spatial and contrast resolution. Anatomical MRI has a modest utility in NM-staging of BCa. However, incorporation of functional MR techniques, such as diffusion weighted MRI can improve the results for lesion detection and staging and multi-parametric MRI`s role is yet to be explored widely. The aim of this review is to present the recent advances in PET/CT and MRI in BCa, with particular focus on improvements in staging.

Implications of pacemakers and implantable cardioverter defibrillators in urological practice

PURPOSE

Pacemakers and implantable cardioverter defibrillators are widely used and often encountered in urology practices worldwide. Safety and performance during electrosurgery, extracorporeal shock wave lithotripsy, magnetic resonance imaging, positron emission tomography and radiotherapy are not clearly defined. We reviewed the literature on their use and implications in urological practice.

MATERIALS AND METHODS

We performed a PubMed® search and all relevant articles were studied to understand the basic functioning of these devices along with the technological advances designed to reduce electromagnetic interference.

RESULTS

A modern permanent pacemaker is comprised of a generator and leads connecting to the atrial or ventricular myocardium with sensing and pacing functions. Implantable cardioverter defibrillators respond to episodes of ventricular tachycardia and fibrillation by discharging a defibrillating current. From a device perspective, several protective mechanisms have been developed in the permanent pacemaker/implantable cardioverter defibrillator to reduce the effects of electromagnetic interference. These involve generator material changes, lead modification, and better sensing and pacing algorithms. Magnetic resonance imaging compatible pacemakers have now been developed and are approved for use in Europe. From a urologist's perspective 5 procedures require the close monitoring of permanent pacemaker/implantable cardioverter defibrillator function. 1) For electrosurgery modifications in the device and in the methods of use have been recommended. 2) For extracorporeal shock wave lithotripsy the European Association of Urology provides some guidance with regard to patients with these devices. 3) During positron emission tomography the pulse generator and the lead area should be covered with lead to protect the device. 4) Magnetic resonance imaging is contraindicated but currently trials are under way for a new pacing system for safe use in the magnetic resonance imaging environment. 5) Patients can undergo radiotherapy with standard precautions but those with an abdominal permanent pacemaker/implantable cardioverter defibrillator require careful planning. Finally, implanted devices should have a full evaluation before and after the procedure.

CONCLUSIONS

Clear guidelines are essential given the rapid advances in technology to enhance patient safety. Magnetic resonance imaging should be avoided in patients without a magnetic resonance imaging compatible device. However, patients can undergo extracorporeal shock wave lithotripsy, radiotherapy and positron emission tomography as long as the device is not in the path.

The association between radiographic response and overall survival in men with metastatic castration-resistant prostate cancer receiving chemotherapy

BACKGROUND

In men with metastatic castration-resistant prostate cancer (CRPC), the association of measurable tumor responses with overall survival (OS) is unknown. The authors retrospectively evaluated the TAX327 phase 3 trial to study this relation.

METHODS

Eligible patients for this analysis included those with World Health Organization (WHO)-defined measurable metastatic disease randomized to receive either docetaxel or mitoxantrone. OS was estimated by using the Kaplan-Meier method, and the prognostic relation of WHO-defined radiologic response with OS was performed by using Cox proportional hazards regression. Landmark analyses evaluated survival from baseline and at 2, 3, 4, and 6 months after baseline.

RESULTS

Four hundred twelve patients enrolled on the TAX327 trial had measurable tumors. Thirty-seven patients exhibited a complete or partial objective response (CR/PR, 9.0%), 116 had stable disease (SD, 28.2%), 99 had progressive disease (PD, 24%) and 160 (38.8%) did not have a after-baseline objective assessment. Partial responders demonstrated longer median OS (29.0 months) than patients with SD (22.1 months) or those with PD (10.8 months) or those who were not assessed (12.7 months). These results remained after landmark analysis. The authors found a significant association between ≥ 30% prostate-specific antigen (PSA) declines and radiologic response, with ≥ 30% PSA declines occurring in all patients with CR/PR, 79.8% of patients with SD, and 34.4% with PD. Radiologic response remained a significant but modest post-treatment prognostic factor for OS after adjusting for treatment, pain response, and ≥ 30% PSA decline (P = .009).

CONCLUSIONS

In men with metastatic CRPC and measurable disease receiving chemotherapy, objective tumor response was prognostic for OS and appeared to complement PSA assessment.

Stromal-epithelial metabolic coupling in cancer: integrating autophagy and metabolism in the tumor microenvironment

Cancer cells do not exist as pure homogeneous populations in vivo. Instead they are embedded in "cancer cell nests" that are surrounded by stromal cells, especially cancer associated fibroblasts. Thus, it is not unreasonable to suspect that stromal fibroblasts could influence the metabolism of adjacent cancer cells, and visa versa. In accordance with this idea, we have recently proposed that the Warburg effect in cancer cells may be due to culturing cancer cells by themselves, out of their normal stromal context or tumor microenvironment. In fact, when cancer cells are co-cultured with fibroblasts, then cancer cells increase their mitochondrial mass, while fibroblasts lose their mitochondria. An in depth analysis of this phenomenon reveals that aggressive cancer cells are "parasites" that use oxidative stress as a "weapon" to extract nutrients from surrounding stromal cells. Oxidative stress in fibroblasts induces the autophagic destruction of mitochondria, by mitophagy. Then, stromal cells are forced to undergo aerobic glycolysis, and produce energy-rich nutrients (such as lactate and ketones) to "feed" cancer cells. This mechanism would allow cancer cells to seed anywhere, without blood vessels as a food source, as they could simply induce oxidative stress wherever they go, explaining how cancer cells survive during metastasis. We suggest that stromal catabolism, via autophagy and mitophagy, fuels the anabolic growth of tumor cells, promoting tumor progression and metastasis. We have previously termed this new paradigm "The Autophagic Tumor Stroma Model of Cancer Metabolism", or the "Reverse Warburg Effect". We also discuss how glutamine addiction (glutaminolysis) in cancer cells fits well with this new model, by promoting oxidative mitochondrial metabolism in aggressive cancer cells.

Preoperative lymph-node staging of invasive urothelial bladder cancer with 18F-fluorodeoxyglucose positron emission tomography/computed axial tomography and magnetic resonance imaging: correlation with histopathology

OBJECTIVE

The treatment and prognosis of bladder cancer are based on the depth of primary tumour invasion and the presence of metastases. A highly accurate preoperative tumour, node, metastasis (TNM) staging is critical to proper patient management and treatment. This study retrospectively investigated the value of ¹⁸F-fluorodeoxyglucose (FDG) positron emission tomography/computed axial tomography (¹⁸F-FDG PET/CT) and magnetic resonance imaging (MRI) for preoperative N staging of bladder cancer. Material and methods. From June 2006 to January 2008, 48 consecutive patients diagnosed with bladder cancer were referred to preoperative staging including MRI and ¹⁸F-FDG PET/CT. Eighteen out of 48 patients underwent radical cystoprostatectomy including removal of lymph nodes for histology, and were included in the study. Values of ¹⁸F-FDG PET/CT and MRI for regional N staging were compared to histopathology findings, the gold standard. Results. ¹⁸F-FDG PET/CT and MRI were performed in 18 patients. The specificities for detection of lymph-node metastases for MRI and ¹⁸F-FDG PET/CT were 80% (n = 15) and 93.33% (n = 15), respectively. The negative predictive values were 80% (n = 15) and 87.5% (n = 16) for MRI and ¹⁸F-FDG PET/CT, respectively. The differences in specificity and negative predictive values were not statistically significant. Conclusions. No significant statistical difference between ¹⁸F-FDG PET/CT and MRI for preoperative N staging of urothelial bladder cancer was found in the study. However, the trend of the data indicates an advantage of ¹⁸F-FDG PET/CT over MRI. Larger prospective studies are needed to elucidate the role of ¹⁸F-FDG PET/CT in N staging of bladder cancer.

PET/CT Imaging and Radioimmunotherapy of Prostate Cancer

Prostate cancer is a common cancer in men and continues to be a major health problem. Imaging plays an important role in the clinical management of patients with prostate cancer. An important goal for prostate cancer imaging is more accurate disease characterization through the synthesis of anatomic, functional, and molecular imaging information. Positron emission tomography (PET)/computed tomography (CT) in oncology is emerging as an important imaging tool. The most common radiotracer for PET/CT in oncology, (18)F-fluorodeoxyglucose (FDG), is not very useful in the imaging of prostate cancer. However, in recent years other PET tracers have improved the accuracy of PET/CT imaging of prostate cancer. Among these, choline labeled with (18)F or (11)C, (11)C-acetate, and (18)F-fluoride has demonstrated promising results, and other new radiopharmaceuticals are under development and evaluation in preclinical and clinical studies. Large prospective clinical PET/CT trials are needed to establish the role of PET/CT in prostate cancer patients. Because there are only limited available therapeutic options for patients with advanced metastatic prostate cancer, there is an urgent need for the development of more effective treatment modalities that could improve outcome. Prostate cancer represents an attractive target for radioimmunotherapy (RIT) for several reasons, including pattern of metastatic spread (lymph nodes and bone marrow, sites with good access to circulating antibodies) and small volume disease (ideal for antigen access and antibody delivery). Furthermore, prostate cancer is also radiation sensitive. Prostate-specific membrane antigen is expressed by virtually all prostate cancers, and represents an attractive target for RIT. Antiprostate-specific membrane antigen RIT demonstrates antitumor activity and is well tolerated. Clinical trials are underway to further improve upon treatment efficacy and patient selection. This review focuses on the recent advances of clinical PET/CT imaging and RIT of prostate cancer.

Significance of incidental focal uptake in prostate on 18-fluoro-2-deoxyglucose positron emission tomography CT images

To evaluate the clinical significance of incidental focal prostate fluorodeoxyglucose (FDG) uptake, we reviewed 18-F-FDG positron emission tomography (PET)/CT scans from 2003 to 2007 and selected cases with focal FDG uptake in prostate. Cases of known prostate cancer were excluded. The maximum standardised uptake value (SUV(max)), site (central or peripheral) and pattern (discrete or ill-defined) of FDG uptake, calcification (present or absent) and prostate volume (<30 or ≥30 cc) were recorded. The PET/CT findings were correlated with serum prostate-specific antigen (PSA) levels, imaging studies, clinical follow-up and biopsy. Of a total of 5119 cases, 63 (1.2%) demonstrated focal FDG uptake in prostate. Eight cases were lost to follow-up. Among the 55 cases with follow-up, malignancy was confirmed by biopsy in 3 (5.4%). The three malignant cases had SUV(max) values of 3.3, 3.6 and 2.3, and all were noted in the peripheral portion of prostate; two of these cases had a discrete FDG uptake pattern, none had calcification corresponding to the FDG uptake area and one had a prostatic volume greater than 30 cc. The mean SUV(max) of 52 benign cases was 3.2 ± 1.7 and focal FDG uptake was noted in the peripheral portion in 34 (65%), 20 (38%) cases showed a discrete FDG uptake pattern, 35 (67%) were accompanied by calcification and 32 (62%) had a prostatic volume greater than 30 cc. The majority of cases demonstrating focal FDG uptake in prostate were benign and no PET/CT finding could reliably differentiate benign from malignant lesions; however, when discrete focal FDG uptake without coincidental calcification is seen, particularly in the peripheral zone of the prostate, further clinical evaluation is recommended.

Serum alkaline phosphatase changes predict survival independent of PSA changes in men with castration-resistant prostate cancer and bone metastasis receiving chemotherapy

OBJECTIVES

The association of a change in serum alkaline phosphatase (ALP) with overall survival OS in men with metastatic castration-resistant prostate cancer (CRPC) receiving chemotherapy is unknown. We evaluated the association of changes in ALP within 90 days with OS in men with CRPC and bone metastases treated with docetaxel or mitoxantrone in the TAX327 trial.

MATERIALS AND METHODS

Eligible patients included those with bony metastatic disease, baseline ALP ≥ 120 u/L (upper limit of normal) and ≥2 post-therapy measurements of ALP available. Survival was estimated using the Kaplan-Meier method and prognostic potential of change in ALP was evaluated using Cox proportional hazards regression. Surrogacy was calculated by the Likelihood Reduction Factor.

RESULTS

601 patients met the eligibility criteria. By day 90, 159 patients had ALP normalization (<120 u/L) and 442 patients did not normalize. Normalization of ALP remained prognostic for OS after adjusting for PSA decline ≥ 30% by day 90 (HR 0.79, 95% CI = 0.65-0.97, P = 0.022). Increase in ALP remained prognostic for OS when adjusting for PSA increase ≥ 50% by day 90 (HR 1.69, 95% CI = 1.33-2.14, P < 0.001). ALP changes did not meet criteria for surrogacy for OS.

CONCLUSIONS

For men with CRPC, bone metastasis and high baseline ALP receiving docetaxel or mitoxantrone chemotherapy, normalization of ALP by day 90 was predictive of better survival independent of ≥30% PSA declines. An increase in ALP by day 90 was also predictive of poor survival independent of ≥50% PSA increase. Given the ready availability of ALP, the validation of our data is warranted.

'Image and treat': an individualized approach to urological tumors

PURPOSE OF REVIEW

The current treatment options for advanced urologic cancers demonstrate limited efficacy. To obtain optimal clinical results, there is a need for new, individualized, therapeutic strategies, which have only recently been applied to these malignancies. Nuclear medicine plays an important role in establishing imaging biomarkers necessary for personalized medicine. This review focuses on the current status of the 'image and treat' approach combining molecular imaging with targeted radionuclide therapy of urological malignancies

RECENT FINDINGS

Tumor-specific targets in uro-oncology are showing promising results for development of personalized therapy using positron emission tomography/computed tomography (PET/CT) molecular imaging and radioimmunotherapy. The antibody cG250, which binds to carbonic anhydrase IX, is being evaluated as a radiolabeled imaging and therapeutic agent in clear-cell renal cell carcinoma. I-cG250 PET/CT has demonstrated excellent targeting of clear-cell renal cell carcinoma. Prostate-specific membrane antigen is a promising target for both PET/CT and radioimmunotherapy of prostate cancer. HER2 may be another potential target in bladder and prostate cancer.

SUMMARY

Tumor-specific targets and biomarkers are being studied for PET/CT and radioimmunotherapy. This may lead to development of new therapeutic strategies. However, considerable investment in new research will be required for personalized medicine to be routinely used in uro-oncology.

Imaging prostate cancer: an update on positron emission tomography and magnetic resonance imaging

Prostate cancer is a common cancer in men and continues to be a major health problem. Imaging plays an essential role in the clinical management of patients. An important goal for prostate cancer imaging is more accurate disease characterization through the synthesis of anatomic, functional, and molecular imaging information. Developments in imaging technologies, specifically magnetic resonance imaging (MRI) and positron emission tomography (PET)/computed tomography (CT), have improved the detection rate of prostate cancer. MRI has improved lesion detection and local staging. Furthermore, MRI allows functional assessment with techniques such as diffusion-weighted MRI, MR spectroscopy, and dynamic contrast-enhanced MRI. The most common PET radiotracer, (18)F-fluorodeoxyglucose, is not very useful in prostate cancer. However, in recent years other PET tracers have improved the accuracy of PET/CT imaging of prostate cancer. Among these, choline (labeled with (18)F or (11)C), (11)C-acetate, and (18)F-fluoride have demonstrated promising results, and other new radiopharmaceuticals are currently under evaluation in preclinical and clinical studies.

Positron emission tomography/computed tomography and radioimmunotherapy of prostate cancer

PURPOSE OF REVIEW

Traditional morphologically based imaging modalities are now being complemented by positron emission tomography (PET)/computed tomography (CT) in prostate cancer. Metastatic prostate cancer is an attractive target for radioimmunotherapy (RIT) as no effective therapies are available. This review highlights the most important achievements within the last year in PET/CT and RIT of prostate cancer.

RECENT FINDINGS

Conflicting results exist on the use of choline for detection of malignant disease in the prostate gland. The role of PET/CT in N-staging remains to be elucidated further. However, F-choline and C-choline PET/CT have been demonstrated to be useful for detection of recurrence. F-choline and F-fluoride PET/CT are useful for detection of bone metastases. Prostate tumor antigens may be used as targets for RIT. Prostate-specific membrane antigen is currently under focus of a number of diagnostic and therapeutic strategies. J591, a monoclonal antibody, which targets the extracellular domain of prostate-specific membrane antigen, shows promising results. HER2 receptors may also have a potential as target for PET/CT imaging and RIT of advanced prostate cancer.

SUMMARY

PET/CT in prostate cancer has proven to play a significant role, in particular for detection of prostate cancer recurrence and bone metastases. RIT of metastatic prostate cancer warrants further investigations.

Retroperitoneal lymph node dissection after chemotherapy

Retroperitoneal lymph node dissection after chemotherapy (PC-RPLND) plays a crucial role in managing patients with advanced germ cell tumours (GCTs). In the last few years improvements in radiographic staging, a better understanding of the role of serum tumour markers, and the introduction of cisplatin-based chemotherapy have all contributed to this surgical therapy. PC-RPLND is necessary when residual radiographic abnormalities are present after chemotherapy. The need for a PC-RPLND in the face of normal findings from computed tomography (CT) is controversial. CT criteria alone are not sufficiently reliable to distinguish viable tumour or teratoma from necrosis. No combination of variables can predict negative retroperitoneal pathology with sufficient accuracy after induction chemotherapy. Unresected teratoma or viable GCT are at least partly chemorefractory and, if untreated, will progress. So completeness of resection is an independent and consistent predictive variable of clinical outcome. In PC-RPLND surgical margins should not be compromised in an attempt to preserve ejaculation, although nerve-sparing dissections are possible in patients with marker normalization after chemotherapy and necrotic tissue in frozen-section histology. In these patients nerve-sparing techniques and the reduction of surgical field to the left- or right-sided template are applicable to preserve antegrade ejaculation and consecutive fertility. The size and location of residual masses coupled with the retroperitoneal desmoplastic reaction make PC-RPLND a technically demanding procedure that should be performed by experienced surgeons in dedicated referral centres.

Positron emission tomography imaging of prostate cancer

Prostate cancer (PCa) is the second leading cause of cancer death among men in the United States. Positron emission tomography (PET), a non-invasive, sensitive, and quantitative imaging technique, can facilitate personalized management of PCa patients. There are two critical needs for PET imaging of PCa, early detection of primary lesions and accurate imaging of PCa bone metastasis, the predominant cause of death in PCa. Because the most widely used PET tracer in the clinic, (18)F-fluoro-2-deoxy-2-D-glucose ((18)F-FDG), does not meet these needs, a wide variety of PET tracers have been developed for PCa imaging that span an enormous size range from small molecules to intact antibodies. In this review, we will first summarize small-molecule-based PET tracers for PCa imaging, which measure certain biological events, such as cell membrane metabolism, fatty acid synthesis, and receptor expression. Next, we will discuss radiolabeled amino acid derivatives (e.g. methionine, leucine, tryptophan, and cysteine analogs), which are primarily based on the increased amino acid transport of PCa cells. Peptide-based tracers for PET imaging of PCa, mostly based on the bombesin peptide and its derivatives which bind to the gastrin-releasing peptide receptor, will then be presented in detail. We will also cover radiolabeled antibodies and antibody fragments (e.g. diabodies and minibodies) for PET imaging of PCa, targeting integrin alpha(v)beta(3), EphA2, the epidermal growth factor receptor, or the prostate stem cell antigen. Lastly, we will identify future directions for the development of novel PET tracers for PCa imaging, which may eventually lead to personalized management of PCa patients.