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We investigated the effectiveness of 11C-choline-positron emission tomography/computed tomography (PET/CT) for evaluating treatment response in patients with prostate cancer or renal cell carcinoma. We performed 34 11C-choline PET/CT scans before/after a combined total of 17 courses of treatment in 6 patients with prostate cancer and 2 with renal cell carcinoma. The 17 treatments including hormonal therapy, radiotherapy, chemotherapy, radium-223, molecular target therapy, radiofrequency ablation, transcatheter arterial embolization, and cancer immunotherapy yielded 1 (5.9%) complete metabolic response (CMR), 3 (17.6%) partial metabolic responses (PMRs), 2 (11.8%) stable metabolic diseases (SMDs), and 11 (64.7%) progressive metabolic diseases (PMDs). Target lesions were observed in bone (n=14), lymph nodes (n=5), lung (n=2), prostate (n=2), and pleura (n=1), with CMR in 4, PMR in 10, SMD in 8 and PMD in 2 lesions. SUVmax values of the target lesions before and after treatment were 7.87±2.67 and 5.29±3.98, respectively, for a mean reduction of -35.4±43.6%. The response for the 8 prostate cancer-treatment courses was PMD, which correlated well with changes in serum prostatic specific antigen (PSA) (7 of 8 cases showed increased PSA). 11C-choline-PET/CT may be an effective tool for detecting viable residual tumors and evaluating treatment response in prostate cancer and renal cell carcinoma patients., Competing Interests: No potential conflict of interest relevant to this article was reported.

Purpose: To evaluate renal cell carcinoma (RCC) findings in acquired cystic disease of the kidney (ACDK) shown by 11 C-choline and FDG PET/CT, and contrast-enhanced CT., Materials and Methods: Six ACDK patients with 7 RCCs underwent 11 C-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 11 C-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 11 C-choline-PET/CT, FDG-PET/CT, and CT was 100% (7/7), 57.1% (4/7), and 42.9% (3/7)., Conclusion: 11 C-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.

Purpose: To compare findings obtained with 11 C-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 11 C-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 11 C-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 11 C-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 11 C-choline and FDG PET/CT, respectively (p < 0.0001)., Conclusion: For staging and restaging of renal cell carcinoma patients, 11 C-choline-PET/CT is significantly more useful than FDG-PET/CT.

Although fluorodeoxyglucose (FDG) positron emission tomography (PET)/computed tomography (CT) has been widely used as a powerful tool in clinical oncologic imaging, its application in urological malignancies is limited. Recently, choline PET/CT has been successfully used for prostate cancer restaging. Here, we report the utility of choline PET/CT for the detection and monitoring of metastatic disease in two cases of renal cell carcinoma (RCC). A 53-year-old woman and a 45-year-old woman underwent FDG and choline PET/CT for evaluation of metastatic lesions in lymph nodes and bone following left and right RCC, respectively, and choline PET/CT demonstrated significantly higher uptake when compared with FDGPET/CT in both cases. Choline PET/CT accurately reflected the remission and progression of diseases in their clinical course, indicating that choline PET/CT could be a useful imaging modality in metastatic RCC.

We compared 11C-choline and FDG PET/CT scan findings for the staging and restaging of prostate cancer. Twenty Japanese prostate cancer patients underwent 11C-choline and FDG PET/CT before (n=5) or after (n=15) treatment. Using a five-point scale, we compared these scanning modalities regarding patient- and lesion-based diagnostic performance for local recurrence, untreated primary tumor, and lymph node and bony metastases. Of the 20 patients, documented local lesions, and node and bony metastases were present in 11 (55.0%), 9 (45.0%), and 13 (65.0%), respectively. The patient-based sensitivity/specificity/accuracy/area under the receiver-operating-characteristic curve (AUC) values for 11C-choline-PET/CT for diagnosing local lesions were 90.9% /100%/ 95.0% / 1.0, whereas those for FDG-PET/CT were 45.5% /100%/ 75.0% / 0.773. Those for 11C-choline-PET/CT for node metastasis were 88.9% /100%/ 95.0% / 0.944, and those for FDG-PET/CT were 44.4%/100%/75.0%/0.722. Those for 11C-choline-PET/CT for bone metastasis were 84.6%/100%/90.0%/0.951, and those for FDG-PET/CT were 76.9% /100%/ 85.0% / 0.962. The AUCs for local lesion and node metastasis differed significantly (p=0.0039, p=0.011, respectively). The lesion-based detection rates of 11C-choline compared to FDG PET/CT for local lesion, and node and bone metastases were 91.7% vs. 41.7%, 92.0% vs. 32.0%, and 94.8% vs. 83.0% (p=0.041, p=0.0030, p<0.0001), respectively. 11C-choline-PET/CT is more useful for the staging and restaging of prostate cancer than FDG-PET/CT in Japanese men., Competing Interests: No potential conflict of interest relevant to this article was reported.

The aim of this study was to compare 11C-choline PET/CT and bone scintigraphy (BS) for detection of bone metastases in patients with prostate cancer. Twenty-one patients with histologically proven prostate cancer underwent 11C-choline PET/CT and BS before (n = 4) or after (n = 17) treatment. Patient-, region-, and lesion-based diagnostic performances of bone metastasis of both 11C-choline PET/CT and BS were evaluated using a five-point scale by two experienced readers. Bone metastases were present in 11 (52.4%) of 21 patients and 48 (32.7%) of 147 regions; 111 lesions were found to have bone metastases. Region-based analysis showed that the sensitivity, specificity, accuracy, and area under the receiver-operating-characteristic curves (AUC) of 11C-choline PET/CT were 97.9%, 99.0%, 98.6%, and 0.9989, respectively; those of BS were 72.9%, 99.0%, 90.5%, and 0.8386, respectively. Sensitivity, accuracy, and AUC significantly differed between the two methods (McNemar test, p = 0.0015, p = 0.0015, and p < 0.0001, respectively). 11C-choline PET/CT detected 110/111 metastatic lesions (99.1%); BS detected 85 (76.6%) (p < 0.0001). According to the CT morphological type, the visualization rates of 11C-choline-PET/BS were 100%/90.3% for the blastic type, 91.7%/8.3% for the lytic type, 100%/100% for the mixed type, and 100%/53.3% for the invisible type, respectively. Significant differences in blastic, lytic, and invisible types were observed between the two methods (p = 0.013, p = 0.0044, and p = 0.023, respectively). In conclusion, 11C-choline PET/CT had greater sensitivity and accuracy than BS for detection of bone involvement in patients with prostate cancer.

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 11 C-choline in the metastatic pancreatic tumor, but no accumulation of 18 F-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.