Update on advances in molecular PET in urological oncology

Disseminated Carcinomatosis of the Bone Marrow from Castration-Resistant Prostate Cancer Revealed by Choline Positron Emission Tomography-Computed Tomography

Introduction

Disseminated carcinomatosis of the bone marrow is caused by cancer metastasis to the bone marrow and is the diagnosis is very difficult by imaging.

Case Presentation

We report a 75-year-old male with disseminated carcinomatosis of the bone marrow from castration-resistant prostate cancer revealed by 11C-choline positron emission tomography-computed tomography (PET/CT). Although he already received radiotherapy to the prostate, combined androgen blockade, enzalutamide and apalutamide, and external beam radiotherapy for the pelvic bone metastases, serum prostate-specific antigen (PSA) value rapidly increased from 32 ng/mL to 104 ng/mL in recent 1 month. Bone scintigraphy showed almost no abnormal uptake in the whole body, whereas 11C-choline PET/CT showed diffuse bone marrow 11C-choline uptake. The disseminated carcinomatosis of the bone marrow was diagnosed from the discordant findings between bone scintigraphy and 11C-choline PET/CT examinations and confirmed pathologically by iliac marrow biopsy pathologically. Although docetaxel therapy was started, PSA value continued rising and he died after 4 months of the diagnosis.

Conclusion

The discordant findings of choline PET/CT and bone scintigraphy can diagnose disseminated carcinomatosis of the bone marrow from prostate cancer.

68 GA-FAPI-04 PET/CT Versus 18 F-FDG PET/CT in Imaging of Malignant Mixed Germ Cell Testicular Tumor

ABSTRACT

18 F-FDG PET/CT imaging was performed for restaging in in a 16-year-old boy who was operated on for right testicular tumor and was diagnosed with malignant mixed germ cell tumor. Mild FDG uptake was observed in 2 nodules in both lungs and retroperitoneal lymph node in the abdomen. 68 Ga-FAPI (fibroblast activation protein inhibitor) 04 PET/CT showed moderate uptake of FAPI in lung nodules and retroperitoneal lymph node. In this case, 68 Ga-FAPI-04 PET/CT was shown to be superior to 18 F-FDG PET/CT in the evaluation of malignant mixed germ cell testicular tumor metastases.

Diagnostic and Therapeutic Challenges in a Patient with Ureteral Metastases from a Triple Negative Breast Cancer

Metastatic ureteral tumors arising from a primary breast carcinoma are extremely rare. They present with hematuria and radiological findings compatible with obstructive ureteral phenomena. We present a case of an 87-year-old woman with a history of lymphoma and triple negative breast cancer (TNBC), during an emergency admission for peptic ulcer, developed macroscopic hematuria. Radiologic and endoscopic investigations revealed a remarkable stenosis at the lower segment of the right ureter, attributed to metastases from her breast carcinoma. We report this case with the aim to make both oncologists and urologists aware of this rare condition.

Incidental Finding of Testicular Seminoma by 18F-Choline PET/CT in a Prostate Cancer Patient

ABSTRACT

An 80-year-old man with a history of prostate cancer, treated with radical prostatectomy and bilateral obturator nodal dissection, underwent an 18F-choline PET/CT because of biochemical recurrence. The scan revealed an intense focal uptake in the right testicle. A subsequent orchifunicumlectomy demonstrated the presence of a classic seminoma. At present, 18F-FDG PET/CT is useful for initial staging of testicular cancer and determining the viability of residual masses >3 cm after completion of treatment, especially in patients with seminoma.

Non-invasive assessment of exfoliated kidney cells extracted from urine using multispectral autofluorescence features

Optimally preserved urinary exfoliated renal proximal tubule cells were assessed by multispectral imaging of cell autofluorescence. We demonstrated different multispectral autofluorescence signals in such cells extracted from the urine of patients with healthy or diseased kidneys. Using up to 10 features, we were able to differentiate cells from individuals with heathy kidneys and impaired renal function (indicated by estimated glomerular filtration rate (eGFR) values) with the receiver operating characteristic area under the curve (AUC) of 0.99. Using the same method, we were also able to discriminate such urine cells from patients with and without renal fibrosis on biopsy, where significant differences in multispectral autofluorescence signals (AUC = 0.90) were demonstrated between healthy and diseased patients (p < 0.05). These findings show that multispectral assessment of the cell autofluorescence in urine exfoliated proximal tubule kidney cells has the potential to be developed as a sensitive, non-invasive diagnostic method for CKD.

Delayed 18F-FDG PET/CT Appearance of Urachal Adenocarcinomas

Background

Urachal carcinoma is a rare urological malignancy. Use of ¹⁸F-FDG PET/CT in urological oncology has developed slowly because of the urinary elimination of ¹⁸F-FDG. We investigated whether delayed postdiuretic ¹⁸F-FDG PET/CT could be used for diagnosing urachal carcinoma.

Methods

This retrospective study included 6 patients who underwent delayed postdiuretic ¹⁸F-FDG PET/CT for the evaluation of urachal carcinoma. The delayed postdiuretic PET/CT parameters and clinical characteristics of urachal carcinoma were investigated.

Results

There was no significant difference in the SUVmax between the primary tumors and the urine in the bladder before delayed diuresis (25.4 ± 19.5 vs. 42.9 ± 31.1, P=0.18). However, the SUVmax of the primary tumors was significantly higher than the SUVmax of urine after delayed diuresis (25.4 ± 19.5 vs. 3.5 ± 1.6, P=0.002). Diuretic ¹⁸F-FDG PET/CT was positive in all patients when compared with normal liver tissues or urine after delayed diuresis. The SUVmax, TLR, and TUR of the primary tumors were 25.4 (range: 7.2–58.9), 7.0 (range: 1.8–14.7), and 6.8 (range: 3.8–11.3), respectively. Delayed postdiuretic ¹⁸F-FDG PET/CT had a negative predictive value of 100% (5/5) for predicting lymph node metastasis. One patient received chemotherapy after radical resection of urachal carcinoma because ¹⁸F-FDG PET/CT found lung metastases, and one patient only received chemotherapy because PET/CT found peritoneal and skeletal metastases.

Conclusions

Delayed postdiuretic ¹⁸F-FDG PET/CT is a useful tool for the preoperative evaluation of urachal carcinoma. ¹⁸F-FDG PET/CT may improve clinical decision making and management of urachal carcinomas.

Delayed post-diuretic 18F-FDG PET/CT for preoperative evaluation of renal pelvic cancer

Background: Application of ¹⁸F^-fluorodeoxyglucose positron emission tomography (¹⁸F-FDG PET) in urological oncology was relatively slowly due to the urinary elimination of ¹⁸F-FDG. We investigated whether delayed post-diuretic ¹⁸F-FDG PET/CT could be used for diagnosing renal pelvic cancer.

Methods: 51 patients were included who underwent delayed post-diuretic ¹⁸F-FDG PET/CT for detecting renal pelvic space-occupying lesions. The comparations of delayed PET/CT parameters and clinical characteristics between renal pelvic cancer and benign polyp were investigated.

Results: Among the 51 patients, 47 were found to have renal pelvic urothelial carcinoma, and 4 had benign polyp. ROC analysis identified the lesion maximum standardized uptake value (SUVmax) of 6.2 as the optimal cut-off value to distinguish from renal pelvic urothelial carcinoma to benign polyp. With the SUVmax cut-off of 6.2, the sensitivity, and specificity for predicting of renal pelvic urothelial carcinoma were 91.5% (43/47), and 100% (4/4). We also found a significant difference in tumor size between the positive (SUVmax > 6.2) and negative (SUVmax ≤ 6.2) PET groups in renal pelvic cancers. In patients with tumor size < 1.1 cm, the probability of being in the negative PET group was 75%. In such patients, a substantial proportion of renal pelvic cancer demonstrated negative SUVmax similar to that in patients with benign polyp.

Conclusion: Delayed ¹⁸F-FDG PET/CT could be used for differentiating renal pelvic cancer from benign polyp. In patients with small tumor size, renal pelvic cancer may present low ¹⁸F-FDG uptake, mimicking the metabolic phenotypes of patients with benign polyp.

Tumour functional imaging by PET

Carcinogenesis is a complex multistep process, characterized by changes at different levels, both genetic and epigenetic, which alter cell metabolism. Positron emission tomography (PET) is a very sensitive image modality that allows to evaluate oncometabolism. PET functionalities are immense, since by labelling a molecule that specifically intervenes in a biochemical regulatory pathway of interest with a positron-emitting radionuclide, we can easily image that pathway. Thus, PET makes possible imaging several metabolic processes and assessing risk prediction, screening, diagnosis, response to therapy, metastization and recurrence. In this paper, we provide an overview of different radiopharmaceuticals developed for PET use in oncology, with a focus on brain tumours, breast cancer, hepatocellular carcinoma, neuroendocrine tumours, bladder cancer and prostate cancer because for these cancer types PET has been shown to be valuable. Most of the described tracers are just used in the research environment, with the aim to assess if these tracers could be able to offer an improvement concerning staging/restaging, characterization and stratification of different types of cancer, as well as therapeutic response assessment. In pursuit of personalized therapy, we briefly discuss the more established metabolic tracers and describe recent work on the development of new radiopharmaceuticals, aware that there will continue to exist diagnostic challenges to face modern cancer medicine.

Clinical staging of upper urinary tract urothelial carcinoma for T staging: Review and pictorial essay

Upper urinary tract urothelial carcinoma is staged using the TNM classification of malignant tumors. Preoperative TNM is important for treatment planning. Computed tomography urography is now widely used for clinical survey of upper urinary tract carcinoma because of its diagnostic accuracy. Computed tomography urography is recommended as the first-line imaging procedure in several guidelines. Several reports stated that computed tomography urography is also useful for staging. However, no educational and practical reviews detailing the T staging of upper urinary tract urothelial carcinomas using imaging are available. We discuss the scanning protocol, T staging using computed tomography urography, limitations, magnetic resonance imaging, computed tomography comparison and pitfalls in imaging of upper urinary tract urothelial carcinoma. A recent study reported the high diagnostic accuracy of computed tomography urography with respect to T3 or higher stage tumors. To date, images that show a Tis-T2 stage have not been reported, but various studies are ongoing. Although magnetic resonance imaging has lower spatial resolution than computed tomography urography, magnetic resonance imaging can be carried out without radiation exposure or contrast agents. Magnetic resonance imaging also offers the unique ability of diffusion-weighted imaging without contrast agent use. Some researchers reported that diffusion-weighted imaging is useful not only for detecting lesions, but for predicting the T stage and tumor grade. We recommend the appropriate use of computed tomography and magnetic resonance while considering the limitations of each modality and the pitfalls in upper urinary tract urothelial carcinoma imaging.

18F-FDG PET/CT and Urothelial Carcinoma: Impact on Management and Prognosis-A Multicenter Retrospective Study

Objectives: To evaluate the ability of 18F-labeled fluoro-2-deoxyglucose positron emission tomography/computed tomography (18F-FDG PET/CT) to predict survivorship of patients with bladder cancer (BC) and/or upper urinary tract carcinoma (UUTC). Materials: Data from patients who underwent FDG PET/CT for suspicion of recurrent urothelial carcinoma (UC) between 2007 and 2015 were retrospectively collected in a multicenter study. Disease management after the introduction of FDG PET/CT in the diagnostic algorithm was assessed in all patients. Kaplan-Meier and log-rank analysis were computed for survival assessment. A Cox regression analysis was used to identify predictors of recurrence and death, for BC, UUTC, and concomitant BC and UUTC. Results: Data from 286 patients were collected. Of these, 212 had a history of BC, 38 of UUTC and 36 of concomitant BC and UUTC. Patient management was changed in 114/286 (40%) UC patients with the inclusion of FDG PET/CT, particularly in those with BC, reaching 74% (n = 90/122). After a mean follow-up period of 21 months (Interquartile range: 4-28 mo.), 136 patients (47.4%) had recurrence/progression of disease. Moreover, 131 subjects (45.6%) died. At Kaplan-Meier analyses, patients with BC and positive PET/CT had a worse overall survival than those with a negative scan (log-rank < 0.001). Furthermore, a negative PET/CT scan was associated with a lower recurrence rate than a positive examination, independently from the primary tumor site. At multivariate analysis, in patients with BC and UUTC, a positive FDG PET/CT resulted an independent predictor of disease-free and overall survival (p < 0,01). Conclusions: FDG PET/CT has the potential to change patient management, particularly for patients with BC. Furthermore, it can be considered a valid survival prediction tool after primary treatment in patients with recurrent UC. However, a firm recommendation cannot be made yet. Further prospective studies are necessary to confirm our findings.

Usefulness of PET/CT 18-FDG for the diagnosis and follow-up of urological, urothelial and kidney tumours

INTRODUCTION

New imaging studies have appeared in recent years for the diagnosis and follow-up of metastatic urological tumours.

MATERIAL AND METHODS

A total of 41 patients were reviewed with suspected recurrence of a urothelial or kidney tumour, analysing the diagnostic performance of PET-CT scans undertaken between 2013 and 2016.

RESULTS

We collected 17 urothelial tumours and 24 renal tumours, with a median follow-up of 30 months. A total of 39.3% of the urothelial tumours were high grade and 29.3% of the kidney tumours were clear cell Fuhrman II. As a whole, the imaging studies detected recurrences in 34 patients. CT was positive in 83% of the patients, while the PET scan was positive in 75.6%, CT/PET coincidence was 50%. The PET scan detected further disease in 41% of the cases compared to 5% by CT. This resulted in a change of therapeutic strategy in 40% of the patients. Sensitivity, specificity, positive predictive value and negative predictive value for the CT and the PET scans were 92% and 92%, 57% and 100%, 92% and 100%, and 57% and 70% respectively.

CONCLUSION

The PET scan showed similar sensitivity for urological tumours to the standard imaging techniques but with higher specificity, positive predictive value and negative predictive value. This led to a change in treatment strategy for 40% of the patients in our series. The PET scan will probably become the standard test in the extension and follow-up studies of most urological tumours.

18F-FDG and 11C-choline uptake in proliferating tumor cells is dependent on the cell cycle in vitro

OBJECTIVE

Among different PET tracers, ¹⁸F-fludeoxyglucose (FDG) and ¹¹C-choline are known to have a high tumor uptake correlated with a high mitotic index of tumor cells. Thus, the uptake of ¹⁸F-FDG and ¹¹C-choline may be dependent on the cell cycle. In the present study, we examined the uptake of ¹⁸F-FDG and ¹¹C-choline in cancer cell lines by cell cycle synchronization to clarify the biological properties of cancer cells with respect to each tracer.

METHODS

HeLa S3 Cells were synchronized by the double thymidine (TdR) block methods. ¹⁸F-FDG and ¹¹C-choline were administered to synchronized cells, and the radioactivity per cell was measured to compare the cellular uptake of the tracers during S, G2/M, and G1 phases. Flow cytometry (FCM) was performed to measure the proportion of cells in G1, S, and G2/M phases. Furthermore, the levels of glucose transporter 1 (GLUT1) and choline transporter-like protein 1 (CTL1) in the cell were evaluated by FCM.

RESULTS

The uptake of ¹⁸F-FDG was the highest in S to G2/M phases, and markedly decreased in G1 phase. The uptake of ¹¹C-choline reached its peak in G2/M, and decreased in G1 phase. The level of GLUT1 expression was similar to that of ¹⁸F-FDG uptake during the cell cycle, and the level of CTL1 expression was similar to that of ¹¹C-choline uptake throughout the cell cycle.

CONCLUSIONS

In this in vitro study, we demonstrated that ¹⁸F-FDG and ¹¹C-choline had the highest uptake in S to G2/M phases and in G2/M phase, respectively, with a rapid decrease in G1 phase. These findings suggest that ¹⁸F-FDG and ¹¹C-choline have a high accumulation in tumor cells with a high mitotic index. Furthermore, our study suggests that the expression of GLUT1 and CTL1 has cell cycle dependence, and the changes of ¹⁸F-FDG and ¹¹C-choline accumulation seem to be caused by the above properties of these transporters.

11C-Choline positive but 18F-FDG negative pancreatic metastasis from renal cell carcinoma on PET

Choline is a new PET tracer, which uptake may occur via a choline-specific transporter protein and be accelerated during the proliferation of tumor cells. We report a 61-year-old woman with a metastatic pancreatic tumor from renal cell carcinoma, measuring 35×40 mm. PET scans demonstrated accumulation of ¹¹C-choline in the metastatic pancreatic tumor, but no accumulation of ¹⁸F-FDG. Choline PET/CT may play a useful and complementary imaging modality, especially when FDG-PET/CT does not show expected findings or when the evaluation of tumor viability is needed, in patients with renal cell carcinoma.

FDG PET/CT as a survival prognostic factor in patients with advanced renal cell carcinoma

Accurate prediction of the outcome of molecular target-based treatment in advanced renal cell carcinoma (RCC) is an important clinical problem. Positron emission tomography/computed tomography using [18F]-2-fluoro-2-deoxyglucose (FDG PET/CT) is a noninvasive tool for the assessment of glucose accumulation which can be a marker of the biological characteristics of the tumor. In this paper, we assess FDG PET/CT as a survival prognostic marker in patients with advanced RCC. The study included 121 patients treated in the years 2011–2016 with a diagnosis of advanced renal cell carcinoma (stage IV, multifocal metastases in all patients). Assessment using FDG PET/CT was conducted by measuring the maximum standard uptake value (SUVmax) for the marker used (the highest SUV measurement result for each patient in a single examination). SUVmax measurements were compared with various clinical risk factors used as prognostic markers. The median follow-up period was 19 months (ranging from 3 to 61 months). SUVmax measurements in all patients ranged from 1.3 to 30.0 (median 6.9). Higher SUVmax was correlated with poorer prognosis. Multi-way analysis with standard risk factors revealed that SUVmax was an independent factor for overall survival (OS; p < 0.003, hazard ratio 1.312, 95% CI 1.147–1.346). For SUVmax < 7.0, median OS was 32 months. For 7.0 ≤ SUVmax < 12.0, median OS was 12.5 months. For SUVmax ≥ 12.0, median OS was 10 months. The differences were statistically significant. A preliminary SUVmax assessment conducted using FDG PET/CT can provide information useful in the prediction of survival of patients with advanced RCC.

Radiobiological Characterization of 64CuCl₂ as a Simple Tool for Prostate Cancer Theranostics

⁶⁴CuCl₂ has recently been proposed as a promising agent for prostate cancer (PCa) theranostics, based on preclinical studies in cellular and animal models, and on the increasing number of human studies documenting its use for PCa diagnosis. Nevertheless, the use of ⁶⁴CuCl₂ raises important radiobiological questions that have yet to be addressed. In this work, using a panel of PCa cell lines in comparison with a non-tumoral prostate cell line, we combined cytogenetic approaches with radiocytotoxicity assays to obtain significant insights into the cellular consequences of exposure to ⁶⁴CuCl₂. PCa cells were found to exhibit increased ⁶⁴CuCl₂ uptake, which could not be attributed to increased expression of the main copper cellular importer, hCtr1, as had been previously suggested. Early DNA damage and genomic instability were also higher in PCa cells, with the tumoral cell lines exhibiting deficient DNA-damage repair upon exposure to ⁶⁴CuCl₂. This was corroborated by the observation that ⁶⁴CuCl₂ was more cytotoxic in PCa cells than in non-tumoral cells. Overall, we showed for the first time that PCa cells had a higher sensitivity to ⁶⁴CuCl₂ than healthy cells, supporting the idea that this compound deserved to be further evaluated as a theranostic agent in PCa.

Imaging of renal cell carcinoma in patients with acquired cystic disease of the kidney: comparison 11C-choline and FDG PET/CT with dynamic contrast-enhanced CT

PURPOSE

To evaluate renal cell carcinoma (RCC) findings in acquired cystic disease of the kidney (ACDK) shown by ¹¹C-choline and FDG PET/CT, and contrast-enhanced CT.

MATERIALS AND METHODS

Six ACDK patients with 7 RCCs underwent ¹¹C-choline and FDG PET/CT, and contrast-enhanced CT before nephrectomy. Findings obtained with 3 imagings were evaluated and sensitivity detecting RCC was compared using 3-point grading scale (negative, equivocal, positive). The equivocal scale used for SUVmax ranged from 2.0 to 3.0 for PET/CT and a peak enhancement value ranging from 20 to 30 HU was used for CT.

RESULT

The histopathologic subtypes of 7 RCCs were clear-cell (n = 4) and ACD-associated RCC (n = 3). The negative/equivocal/positive grading results were 0/0/7 for ¹¹C-choline-PET/CT, 0/3/4 for FDG-PET/CT, and 2/2/3 for CT. Three equivocal cases by FDG-PET/CT were 2 clear-cell RCCs and 1 ACD-associated RCC. CT of 3 ACD-associated RCCs showed negativity for 2 and equivocality for 1. Sensitivity defining equivocal interpretation as negative for ¹¹C-choline-PET/CT, FDG-PET/CT, and CT was 100% (7/7), 57.1% (4/7), and 42.9% (3/7).

CONCLUSION

¹¹C-choline-PET/CT was more sensitive to detect RCC in ACDK as compared to FDG-PET/CT and contrast-enhanced CT in our series. FDG-PET/CT may be limited for detecting clear-cell RCC, while CT may have difficulty with detection of ACD-associated RCC.

Comparison between the diagnostic accuracies of 18F-fluorodeoxyglucose positron emission tomography/computed tomography and conventional imaging in recurrent urothelial carcinomas: a retrospective, multicenter study

PURPOSE

To determine the performance accuracy of 18F-fluorodeoxyglucose positron emission tomography/computed tomography (FDG PET/CT) after primary tumor treatment for both bladder cancer (BC) and upper tract urothelial cancer (UTUC). To compare the accuracy of FDG PET/CT with that of contrast-enhanced-ceCT and magnetic resonance imaging (MRI).

METHODS

Data of patients with recurrent urothelial carcinomas (UC) after primary treatment were collected in a retrospective, international multicenter study. Inclusion criteria were (1) patients with a known history of UC in the BC and/or in the UTUC; (2) PET/CT images after curative intent treatment of the primary tumor; (3) conventional imaging modalities (abdominal ceCT or MRI, or total body ceCT, and chest X-ray: called C.I.) performed no more than 3 months from PET/CT; (4) available standard of reference (e.g., histological data or follow-up imaging modalities) for the validation of PET/CT findings. Exclusion criteria were other abdominal tumors, chemotherapy administration prior to and/or concomitant to imaging, and non-urothelial histologic variants. Sensitivities, specificities, positive, and negative predictive values were evaluated for all patients and separately for bladder and UTUC.

RESULTS

Overall, 287 patients were enrolled. Two-hundred thirteen patients underwent cystectomy (74.2%), 35 nephroureterectomy (12.2%), 31 both cystectomy + nephroureterectomy (10.8%), 5 both cystectomy + conservative treatment for UTUC (1.4%), and 3 (1%) other types of nephron-sparing treatments for UTUC. Neoadjuvant and adjuvant treatments were performed in 36 (12.5%) and 111 (38.7%) patients, respectively. Sensitivity and specificity (95% confidence intervals) of PET/CT for the detection of recurrent UC were 94% (91% to 96%) and 79% (68% to 88%), respectively. However, sensitivity was higher for BC than UTUC (95% vs. 85%) while specificity was lower in BC (78% vs. 85% for BC and UTUC, respectively). PET/CT and C.I. findings were available in 198 patients. The results were positively concordant in 137 patients, negatively concordant in 23 patients, and discordant in 38 patients (20 negative at C.I. vs. positive at PET/CT and 18 positives at ceCT/MRI vs. negative at PET/CT) (K Cohen = 0.426; p < 0.001). Sensitivities, specificities, and accuracies (95% confidence intervals) of PET/CT vs. C.I. for the detection of recurrent BC and UTUC were 94% (90% to 97%) vs. 86% (81% to 92%), 79% (67% to 92%) vs. 59% (44% to 74%), and 91% (87% to 95%) vs. 81% (75% to 86%), respectively.

CONCLUSIONS

FDG PET/CT has a high diagnostic accuracy for the identification of recurrent UC, particularly in patients with BC. Moreover, its accuracy outperforms C.I. for both BC and UTUC.

Diagnostic performance of 11C-choline PET/CT and FDG PET/CT for staging and restaging of renal cell cancer

PURPOSE

To compare findings obtained with ¹¹C-choline and FDG PET/CT scanning for renal cell carcinoma staging and restaging.

MATERIALS AND METHODS

Twenty-eight renal cell carcinoma patients whose histological subtype was clear cell type in 26 and papillary type in 2, while Fuhrman nuclear grade was G1,2 in 16 and G3,4 in 12, underwent both ¹¹C-choline and FDG PET/CT examinations before (n = 10) and/or after (n = 18) treatment, then those scanning modalities were compared in regard to patient- and lesion-based diagnostic performance using 5 grading scores. Final diagnosis in each case was obtained based on histopathology, conventional radiological imaging, and clinical follow-up findings. The differences between ¹¹C-choline and FDG PET/CT findings were evaluated using receiver-operating-characteristic (ROC) analysis and a McNemar test.

RESULTS

Patient-based sensitivity, specificity, positive predictive, negative predictive, accuracy, and area under the ROC curve (AUC) values for ¹¹C-choline PET/CT for staging and restaging were 88.0% (22/25), 66.7% (2/3), 95.7% (22/23), 40.0% (2/5), 85.7% (24/28), and 0.887, respectively, while those for FDG-PET/CT were 56.0% (14/25), 66.7% (2/3), 93.3% (14/15), 15.4% (2/13), 57.1% (16/28), and 0.647, respectively. Sensitivity, accuracy, and AUC were significantly different (p = 0.013, p = 0.013, p = 0.012, respectively). Among the 120 lesions, those with kidney, lung, lymph node, bone, pancreas, venous tumor thrombosis, adrenal gland, liver, or skin localization numbered 15, 64, 16, 13, 4, 3, 2, 2, and 1, respectively. For all 120 lesions, 75 (62.5%) and 47 (39.2%) were detected by ¹¹C-choline and FDG PET/CT, respectively (p < 0.0001).

CONCLUSION

For staging and restaging of renal cell carcinoma patients, ¹¹C-choline-PET/CT is significantly more useful than FDG-PET/CT.

Comparison of 11C-choline Positron Emission Tomography/Computed Tomography (PET/CT) and Conventional Imaging for Detection of Recurrent Prostate Cancer

We aimed to compare ¹¹C-choline positron emission tomography/computed tomography (PET/CT) with conventional imaging, including pelvic magnetic resonance imaging (MRI), contrast-enhanced chest, abdomen, and pelvic computed tomography (CT), and bone scintigraphy, for prostate cancer restaging. Thirty patients (median prostate-specific antigen [PSA: 11.8 ng/mL]) with suspected recurrent prostate cancer following definitive treatment underwent ¹¹C-choline PET/CT and conventional imaging, including pelvic MRI, contrast-enhanced chest, abdomen, and pelvic CT, and bone scintigraphy. The results were compared with regard to patient- and lesion-based diagnostic performance for local recurrence, and for lymph node and bony metastases using receiver operating characteristic (ROC) analysis and McNemar’s test. Documented local recurrence and node and bony metastases were present in 11 (36.7%), 10 (33.3%), and 17 (56.7%) cases, respectively, of the enrolled patients. Patient-based sensitivity / specificity / accuracy / area under the ROC curve for ¹¹C-choline-PET/CT for diagnosing local recurrence were 90.9% / 94.7% / 93.3% / 0.975 and for conventional imaging were 90.9% / 100% / 96.7% / 1.0. Those who underwent ¹¹C-choline-PET/CT for node metastasis were 90.0% / 95.0% / 93.3% / 0.925 and for conventional imaging were 70.0% / 95.0% / 86.7% / 0.905. Those who underwent ¹¹C-choline-PET/CT for bone metastasis were 94.1% / 92.3% / 93.3% / 0.991 and who underwent conventional imaging were 94.1% / 84.6% / 90.0% / 0.982. No significant differences were observed among them. The lesion-based detection rate of ¹¹C-choline PET/CT for local recurrences and node and bone metastases as compared to conventional imaging was 92.9% (13/14) vs. 92.9% (13/14); 87.1% (27/31) vs. 54.8% (17/31); and 96.9% (219/226) vs. 90.3% (204/226) respectively, with significant differences noted for detection of node and bone lesions (p=0.0044 and p=0.00030, respectively). ¹¹C-choline-PET/CT is more accurate in the detection of recurrent prostate cancer nodes and bony metastatic lesions compared to conventional imaging and has the advantage of restaging the disease in a single step.

Clinically significant association of elevated expression of nuclear factor E2-related factor 2 expression with higher glucose uptake and progression of upper urinary tract cancer

BACKGROUND

There is growing evidence that the transcription factor nuclear factor E2-related factor 2 (Nrf2) is the major participant in regulating antioxidants and pathways for detoxifying reactive oxygen species (ROS), as well as having a vital role in tumor proliferation, invasion, and chemoresistance. It was also recently reported that Nrf2 supports cell proliferation by promoting metabolic activity. Thus, Nrf2 is involved in progression of cancer. Upper urinary tract urothelial carcinoma (UTUC) is a biologically aggressive tumor with high rates of recurrence and progression, resulting in a poor prognosis. However, the role of Nrf2 in UTUC is largely unknown.

METHODS

In order to study the role of Nrf2 in UTUC from the metabolic perspective, we retrospectively assessed Nrf2 expression in the surgical specimen and the preoperative maximum standard glucose uptake (SUVmax) on [¹⁸F]fluorodeoxy-glucose positron emission tomography (¹⁸F-FDG-PET) of 107 patients with UTUC who underwent radical nephroureterectomy.

RESULTS

Increased expression of Nrf2 in the primary lesion was correlated with less differentiated histology, local invasion, and lymph node metastasis, and was also an independent indicator of shorter overall survival according to multivariate analysis. Furthermore, increased expression of Nrf2 was associated with higher preoperative SUVmax by the primary tumor on ¹⁸F-FDG-PET, while Nrf2 expression and SUVmax were also significantly correlated in the metastatic lymph nodes. Among the 18 patients with lymph node metastasis at nephroureterectomy who underwent retroperitoneal lymph node dissection and received adjuvant chemotherapy, the patients with higher Nrf2 expression in the primary tumor had worse recurrence-free survival.

CONCLUSIONS

These results suggest that constitutive activation of Nrf2 might be linked with tumor aerobic glycolysis and progression of UTUC, indicating that Nrf2 signaling in the tumor microenvironment promotes progression of UTUC.

Tyrosine-Kinase Inhibitors Therapies with Mainly Anti-Angiogenic Activity in Advanced Renal Cell Carcinoma: Value of PET/CT in Response Evaluation

Renal cell carcinoma (RCC) is the most frequent renal tumor and the majority of patients are diagnosed with advanced disease. Tumor angiogenesis plays a crucial role in the development and progression of RCC together with hypoxia and glucose metabolism. These three pathways are strictly connected to the cell growth and proliferation, like a loop that is self-feeding. Over the last few years, the ever-deeper knowledge of its contribution in metastatic RCC led to the discovery of numerous tyrosine kinase inhibitors (TKIs) targeting pro-angiogenic receptors at different levels such as sunitinib, sorafenib, pazopanib, axitinib, tivozanib, and dovitinib. As anti-angiogenic agents, TKIs interfere the loop, being able to inhibit tumor proliferation. TKIs are now available treatments for advanced RCC, which demonstrated to improve overall survival and/or progression free survival. Their effects can be detectable early on Positron Emission Tomography/Computed Tomography (PET/CT) by change in ¹⁸F-fluoro-2-deoxy-2-d-glucose (¹⁸F-FDG) uptake, the main radiotracer used to date, as a strong indicator of biological response. ¹⁸F-FDG PET/CT demonstrated an ability to predict and monitor disease progression, allowing an early and reliable identification of responders, and could be used for image-guided optimization and "personalization" of anti-angiogenic regimens. New radiotracers for biometabolic imaging are currently under investigation, which exploit the other pathways involved in the cancer process, including cellular proliferation, aerobic metabolism, cell membrane synthesis, hypoxia and amino acid transport, as well as the angiogenic process, but they require further studies.

11C-Choline-Avid but 18F-FDG-Nonavid Prostate Cancer with Lymph Node Metastases on Positron Emission Tomography

Choline is a new positron emission tomography (PET) tracer useful for detection of prostate cancer and metastatic lesions. We report a 70-year-old man with prostate cancer and multiple abdominal, pelvic, and inguinal node metastases. PET scans demonstrated accumulation of ¹¹C-choline in the primary tumor and lymph node metastases but no accumulation of ¹⁸F-FDG. Choline PET/computed tomography may be useful for diagnosis of advanced prostate cancer with suspected metastatic lesions and treatment planning.

Clinical Translation of a Dual Integrin αvβ3- and Gastrin-Releasing Peptide Receptor-Targeting PET Radiotracer, 68Ga-BBN-RGD

This study aimed to document the first-in-human application of a ⁶⁸Ga-labeled heterodimeric peptide BBN-RGD (bombesin-RGD) that targets both integrin α_vβ₃ and gastrin-releasing peptide receptor (GRPR). We evaluated the safety and assessed the clinical diagnostic value of ⁶⁸Ga-BBN-RGD PET/CT in prostate cancer patients in comparison with ⁶⁸Ga-BBN.

METHODS

Five healthy volunteers (4 men and 1 woman; age range, 28-53 y) were enrolled to validate the safety of ⁶⁸Ga-BBN-RGD. Dosimetry was calculated using the OLINDA/EXM software. Thirteen patients with prostate cancer (4 newly diagnosed and 9 posttherapy) were enrolled. All the patients underwent PET/CT scans 15-30 min after intravenous injection of 1.85 MBq (0.05 mCi) per kilogram of body weight of ⁶⁸Ga-BBN-RGD and also accepted ⁶⁸Ga-BBN PET/CT within 2 wk for comparison.

RESULTS

With a mean injected dose of 107.3 ± 14.8 MBq per patient, no side effect was found during the whole procedure and 2 wk follow-up, demonstrating the safety of ⁶⁸Ga-BBN-RGD. A patient would be exposed to a radiation dose of 2.90 mSv with an injected dose of 129.5 MBq (3.5 mCi), which is much lower than the dose limit set by the Food and Drug Administration. In 13 patients with prostate cancer diagnosed by biopsy, ⁶⁸Ga-BBN-RGD PET/CT detected 3 of 4 primary tumors, 14 metastatic lymph nodes, and 20 bone lesions with an SUV_max of 4.46 ± 0.50, 6.26 ± 2.95, and 4.84 ± 1.57, respectively. Only 2 of 4 primary tumors, 5 lymph nodes, and 12 bone lesions were positive on ⁶⁸Ga-BBN PET/CT, with the SUV_max of 2.98 ± 1.24, 4.17 ± 1.89, and 3.61 ± 1.85, respectively.

CONCLUSION

This study indicates the safety and efficiency of a new type of dual integrin α_vβ₃- and GRPR-targeting PET radiotracer in prostate cancer diagnosis and staging.