18F-choline PET Research Articles

The value of baseline 18F-sodium fluoride and 18F-choline PET activity for identifying responders to radium-223 treatment in castration-resistant prostate cancer bone metastases

ObjectivesTo investigate whether baseline 18F-sodium fluoride (NaF) and 18F-choline PET activity is associated with metastatic castration-resistant prostate cancer (mCRPC) global and individual bone metastases’ DWI MR imaging response to radium-223 treatment.MethodsThirty-six bone-only mCRPC patients were prospectively recruited from three centers. Whole-body (WB)-MRI with DWI and 18F-NaF and 18F-choline PET/CT were performed at therapy baseline and 8-week intervals. In each patient, bone disease median global (g)ADC change between baseline and follow-up was calculated. Additionally, up to five bone target lesions per patient were delineated and individual median ADC change recorded. An ADC increase > 30% defined response per-patient and per-lesion. For the same targets, baseline 18F-NaF and 18F-choline PET SUVmax were recorded. Mean SUVmax across patient targets was correlated with gADC change and lesion SUVmax with per-lesion ADC change.ResultsA total of 133 lesions in 36 patients (14 responders) were analyzed. 18F-NaF PET per-patient mean SUVmax was significantly higher in responders (median = 56.0 versus 38.7 in non-responders; p = 0.008), with positive correlation between SUVmax and gADC increase (rho = 0.42; p = 0.015). A 48.7 SUVmax threshold identified responders with 77% sensitivity and 75% specificity. Baseline 18F-NaF PET per-lesion SUVmax was higher in responding metastases (median = 51.6 versus 31.8 in non-responding metastases; p = 0.001), with positive correlation between baseline lesion SUVmax and ADC increase (rho = 0.39; p < 0.001). A 36.8 SUVmax threshold yielded 72% sensitivity and 63% specificity. No significant association was found between baseline 18F-choline PET SUVmax and ADC response on a per-patient (p = 0.164) or per-lesion basis (p = 0.921).Conclusion18F-NaF PET baseline SUVmax of target mCRPC bone disease showed significant association with response to radium-223 defined by ADC change.Clinical relevance statement18F-sodium fluoride PET/CT baseline maximum SUV of castration-resistant prostate cancer bone metastases could be used as a predictive biomarker for response to radium-223 therapy.Key Points• 18F-sodium fluoride PET baseline SUVmax of castration-resistant prostate cancer bone metastases showed significant association with response to radium-223.• Baseline 18F-sodium fluoride PET can improve patient selection for radium-223 therapy.• Change in whole-body DWI parameters can be used for response correlation with baseline 18F-sodium fluoride PET SUVmax in castration-resistant prostate cancer bone metastases.

Detection, resection and cure: a systematic review and meta-analysis of 18F-choline PET in primary hyperparathyroidism.

Primary hyperparathyroidism (pHPT) is a common endocrine disorder caused by an autonomous overproduction of parathyroid hormone (PTH) by a parathyroid gland. Over the last decade, 18F-choline (FCH) PET has emerged as a highly performant imaging technique for guiding parathyroidectomy. As cure is the goal of surgery, the main aims of this study were to summarize patient-based sensitivity, positive predictive value (PPV), and cure rate of FCH PET guided surgery in the surgical management of pHPT. We conducted a systematic review and metaanalysis according to the PRISMA Guidelines. A literature search was performed in the PubMed, Web of Science and Cochrane databases, last updated November 2022. Original articles on choline PET in patients with pHPT mentioning patient-based sensitivity, PPV and cure rate were retained. Quality of included studies was assessed using the QUADAS-2 Tool. Patient-based sensitivity, PPV and cure rate were pooled by using a random-effects model. Twenty-three studies including 1716 patients were included for quantitative assessment. FCH PET showed a pooled patient-based sensitivity of 93.8% (95% CI: 89.8-96.3) and PPV of 97% (95% CI: 92.8-98.8) in patients with pHPT. Parathyroid surgery was performed in 1129 patients. The pooled cure rate of PET-guided surgery was 92.8% (95% CI: 87.4-96.0). Heterogeneity was shown to be moderate for all effect sizes. FCH PET showed a high patient-based sensitivity, PPV and cure rate of PET guided surgery in patients with pHPT.

Deep Learning-Based Denoising in Brain Tumor CHO PET: Comparison with Traditional Approaches

18F-choline (CHO) PET image remains noisy despite minimum physiological activity in the normal brain, and this study developed a deep learning-based denoising algorithm for brain tumor CHO PET. Thirty-nine presurgical CHO PET/CT data were retrospectively collected for patients with pathological confirmed primary diffuse glioma. Two conventional denoising methods, namely, block-matching and 3D filtering (BM3D) and non-local means (NLM), and two deep learning-based approaches, namely, Noise2Noise (N2N) and Noise2Void (N2V), were established for imaging denoising, and the methods were developed without paired data. All algorithms improved the image quality to a certain extent, with the N2N demonstrating the best contrast-to-noise ratio (CNR) (4.05 ± 3.45), CNR improvement ratio (13.60% ± 2.05%) and the lowest entropy (1.68 ± 0.17), compared with other approaches. Little changes were identified in traditional tumor PET features including maximum standard uptake value (SUVmax), SUVmean and total lesion activity (TLA), while the tumor-to-normal (T/N ratio) increased thanks to smaller noise. These results suggested that the N2N algorithm can acquire sufficient denoising performance while preserving the original features of tumors, and may be generalized for abundant brain tumor PET images.

18F-Choline PET/CT, MRI, and Software-Based Image Fusion Analysis in Patients With Primary Hyperparathyroidism.

The aim of this study was to evaluate the diagnostic performance of 18F-choline PET and MRI in patients with primary hyperparathyroidism. Furthermore, the additional value of software-based PET/MRI scan fusion was analyzed. This retrospective study includes 42 patients (38 women) with an age between 32.5 and 79.1 years. PET/CT scans were performed on a dedicated system after injection of 250 to 350 MBq 18F-choline. For the MRI examination, T1-weighted images of the cervical region were used. The image fusion was made by anatomical coregistration using an automated algorithm based on mutual information. A total of 46 lesions were discovered and histologically confirmed in 42 patients. Histopathological examination revealed 38 adenomas and 8 hyperplasias. This means that, in 4 of these 42 patients, 2 lesions per patient were discovered. PET/CT also detected 46 abnormal findings, but only 43 were correctly recognized, whereas the other 3 were false-positive (FP). Six lesions could not be detected correctly: 3 were FP and 3 false-negative, which resulted in a sensitivity of 93.5% and a specificity of 97.5%. The site-specific evaluation showed 18 true-positive enlarged parathyroid glands with MRI, but also produced 13 FP findings and failed to detect 28 lesions; the sensitivity and specificity are thus 39.1% and 89.3%, respectively. The difference in detection rate between 18F-choline PET/CT and MRI was statistically significant (P < 0.001). 18F-choline PET/CT is clearly superior to MRI for localization diagnostics in primary hyperparathyroidism. Image fusion of both modalities can be helpful for more precise anatomical assignment.

Prognostic Value of 18F-Choline PET/CT in Patients with Metastatic Castration-Resistant Prostate Cancer Treated with Radium-223.

We aimed to investigate the role of positron emission computed tomography (PET/CT) with 18F-choline for predicting the outcome of metastatic castration-resistant prostate cancer (mCRPC) submitted to treatment with Radium-223 (223Ra-therapy). Clinical records of 20 mCRPC patients submitted to PET/CT with 18F-choline before 223Ra-therapy were retrospectively evaluated. The following PET-derived parameters were calculated: number of lesions, maximum and mean standardized uptake values (SUVmax, SUVmean), lean body mass corrected SUV peak (SULpeak), metabolic tumor volume (MATV), and total lesion activity (TLA). After 223Ra-therapy, all patients underwent regular follow-up until death. The predictive power of clinical and PET-derived parameters on overall survival (OS) was assessed by Kaplan–Meier analysis and the Cox proportional hazard method. All the patients showed 18F-choline-avid lesions at baseline PET/CT. Among the enrolled subjects, eleven (55%) completed all the six scheduled cycles of 223Ra-therapy; seven (35%) were responders according to imaging and biochemical parameters. Mean OS was 12.7 ± 1.4 months: by Kaplan–Meier analysis, number of lesions, PSA level and TLA were significantly correlated with OS. In multivariate Cox analysis, TLA remained the only significant predictor of survival (p = 0.003; hazard ratio = 7.6, 95% confidence interval = 1.9–29.5 months). 18F-choline PET may be useful for patients’ stratification before 223Ra-therapy. In particular, high metabolically active tumor burden (i.e., TLA) was predictive of poor outcome.

886P - Efficacy of enzalutamide in hormone-sensitive metastatic prostate cancer: Clinical utility of 18F-choline PET and whole body MRI

BackgroundAR-inhibition with Enzalutamide may be an attractive alternative for 1L treatment of men with hormone-sensitive prostate cancer compared to androgen deprivation therapy (ADT). There is an unmet need for robust, reproducible imaging technology allowing accurate quantification and qualification of bone plus soft tissue metastases and assessment of early tumour responses to novel agents. PET/CT or WB MRI imaging offer advantage over traditional bone and CT scans. MethodsSixty patients with metastatic hormone-sensitive PC were included in this prospective cohort study. Patients received Enzalutamide 160mg once daily until progression of disease. Imaging tests were performed at baseline and bone scintigraphy and CT repeated at 3 month intervals, 18F-choline PET/CT at 2 weeks, 2, 6, 9 and 12 months and WB-MRI at 6 and 12 months. Enumeration of circulating tumor cells and quality of life assessments were secondary outcomes. ResultsSixty patients with a median age of 72 yrs (range 57−85) and a median PSA of 62.8μg/L (range 3-622) were enrolled. This study is ongoing; all of the first 50 patients experienced a≥50% PSA decline and 49 a≥90% PSA decline. Choline-PET imaging and WB MRI were more frequently able to detect metastases and measure favorable responses than bone scan or CT thorax and abdomen. Investigator and central review of all imaging results are ongoing. Treatment was well tolerated. Conclusions18F-choline PET/CT and WB-MRI were superior in detection of bone and lymph node metastases and 18F-choline PET/CT was useful for early response detection already at 2 weeks. Based on results both 18F-choline-PET and WB MRI imaging have great clinical utility in aiding clinicians treating men with hormone-sensitive metastatic prostate cancer. Clinical trial identificationNCT02815033. Legal entity responsible for the studyEuropean Uro-Oncology Group (EUOG). FundingAstellas Pharma. DisclosureAll authors have declared no conflicts of interest.

Macroscopic locoregional relapse from prostate cancer: which role for salvage radiotherapy?

Salvage radiotherapy (SRT) after radical prostatectomy for prostate cancer (PCa) is recommended as soon as PSA rises above 0.20ng/ml, but many patients (pts) still experience local macroscopic relapse. The aim of this multicentric retrospective analysis was to evaluate the role of SRT in pts with macroscopic relapse. From 2001 to 2016, 105 consecutive pts with macroscopic PCa relapse underwent SRT ± androgen deprivation therapy (ADT). Mean age was 72years. At time of relapse, 29 pts had a PSA value < 1.0ng/mL, 50 from 1.1 to 5, and 25 pts > 5. Before SRT, 23 pts had undergone 18F-choline PET and 15 pts pelvic MRI. Ninety-four pts had prostatic bed relapse only, and four nodal involvement. Fifty-one pts were previously submitted to first-line ADT, while 6 pts received ≥ 2 lines. At a median follow-up of 52months, 89 pts were alive, while 16 were dead. Total RT dose to macroscopic lesions was > 70Gy in 58 pts, 66-70Gy in 43, and < 66Gy in 4 pts. In 72 pts, target volume encompassed only the prostatic bed with sequential boost to macroscopic site; 33 pts received prophylactic pelvic RT. Ten-year overall survival was 76.1%, while distant metastasis-free survival was 73.3%. No grade 4-5 toxicities were found. SRT ± ADT for macroscopic relapse showed a favorable oncological outcome supporting its important role in this scenario. Data from this series suggest that SRT may either postpone ADT or improve results over ADT alone in appropriately selected pts.

Impact of time-of-flight PET on quantification accuracy and lesion detection in simultaneous 18F-choline PET/MRI for prostate cancer

BackgroundAccurate attenuation correction (AC) is an inherent problem of positron emission tomography magnetic resonance imaging (PET/MRI) systems. Simulation studies showed that time-of-flight (TOF) detectors can reduce PET quantification errors in MRI-based AC. However, its impact on lesion detection in a clinical setting with 18F-choline has not yet been evaluated. Therefore, we compared TOF and non-TOF 18F-choline PET for absolute and relative difference in standard uptake values (SUV) and investigated the detection rate of metastases in prostate cancer patients.ResultsNon-TOF SUV was significantly lower compared to TOF in all osseous structures, except the skull, in primary lesions of the prostate, and in pelvic nodal and osseous metastasis. Concerning lymph node metastases, both experienced readers detected 16/19 (84%) on TOF PET, whereas on non-TOF PET readers 1 and 2 detected 11 (58%), and 14 (73%), respectively. With TOF PET readers 1 and 2 detected 14/15 (93%) and 11/15 (73%) bone metastases, respectively, whereas detection rate with non-TOF PET was 73% (11/15) for reader 1 and 53% (8/15) for reader 2. The interreader agreement was good for osseous metastasis detection on TOF (kappa 0.636, 95% confidence interval [CI] 0.453–0.810) and moderate on non-TOF (kappa = 0.600, CI 0.438–0.780).ConclusionTOF reconstruction for 18F-choline PET/MRI shows higher SUV measurements compared to non-TOF reconstructions in physiological osseous structures as well as pelvic malignancies. Our results suggest that addition of TOF information has a positive impact on lesion detection rate for lymph node and bone metastasis in prostate cancer patients.

Accuracy of tumor segmentation from multi-parametric prostate MRI and 18F-choline PET/CT for focal prostate cancer therapy applications

BackgroundThe study aims to assess the accuracy of multi-parametric prostate MRI (mpMRI) and 18F-choline PET/CT in tumor segmentation for clinically significant prostate cancer. 18F-choline PET/CT and 3 T mpMRI were performed in 10 prospective subjects prior to prostatectomy. All subjects had a single biopsy-confirmed focus of Gleason ≥ 3+4 cancer. Two radiologists (readers 1 and 2) determined tumor boundaries based on in vivo mpMRI sequences, with clinical and pathologic data available. 18F-choline PET data were co-registered to T2-weighted 3D sequences and a semi-automatic segmentation routine was used to define tumor volumes. Registration of whole-mount surgical pathology to in vivo imaging was conducted utilizing two ex vivo prostate specimen MRIs, followed by gross sectioning of the specimens within a custom-made 3D-printed plastic mold. Overlap and similarity coefficients of manual segmentations (seg1, seg2) and 18F-choline-based segmented lesions (seg3) were compared to the pathologic reference standard.ResultsAll segmentation methods greatly underestimated the true tumor volumes. Human readers (seg1, seg2) and the PET-based segmentation (seg3) underestimated an average of 79, 80, and 58% of the tumor volumes, respectively. Combining segmentation volumes (union of seg1, seg2, seg3 = seg4) decreased the mean underestimated tumor volume to 42% of the true tumor volume. When using the combined segmentation with 5 mm contour expansion, the mean underestimated tumor volume was significantly reduced to 0.03 ± 0.05 mL (2.04 ± 2.84%). Substantial safety margins up to 11–15 mm were needed to include all tumors when the initial segmentation boundaries were drawn by human readers or the semi-automated 18F-choline segmentation tool. Combining MR-based human segmentations with the metabolic information based on 18F-choline PET reduced the necessary safety margin to a maximum of 9 mm to cover all tumors entirely.ConclusionsTo improve the outcome of focal therapies for significant prostate cancer, it is imperative to recognize the full extent of the underestimation of tumor volumes by mpMRI. Combining metabolic information from 18F-choline with MRI-based segmentation can improve tumor coverage. However, this approach requires confirmation in further clinical studies.

18-F choline PET CT in primary diagnosis of prostate cancer

18-F choline PET CT in primary diagnosis of prostate cancer

EP-1222: Impact of 18F-Choline PET in the decision making strategy of treatment volumes in definitive prostate radiotherapy

EP-1222: Impact of 18F-Choline PET in the decision making strategy of treatment volumes in definitive prostate radiotherapy

Needle track recurrence after transrectal prostate biopsy detected by 18F-Choline PET–CT

Needle track recurrence after transrectal prostate biopsy detected by 18F-Choline PET–CT

Modelling the impact of injection time on the bolus shapes in PET-MRI AIF Conversion

With the introduction of combined PET/MRI systems, AIF conversion can be made under certain circumstances (see [1]). We propose a model that allows modification of the injection parameters in the AIF fit to account for differences caused by different injection durations [2]. Brain 18F-Choline PET and DSC-MRI data were obtained using Siemens mMR. The MR contrast agent was injected with a rate of 4ml/sec and the PET tracer was injected manually. Perfusion Mismatch Analyzer [3] was used to extract the MRI-AIF. Carotid arteries were segmented on a post contrast MPRAGE image. PET frames were registered onto this MPRAGE image using rigid registration and partial volume correction was done using the iterative Yang method [4]. The AIFs were fitted using a convolution of a ‘double Butterworth’ function, representing the injection, with a tri-exponential function representing the elimination [Eq. 1]. The bolus shape can be adjusted by changing Δτ (τ2 - τ1). This was tested with a population based MRI AIF [5], as well as with clinical data. 1 where For the population based input function, Figure ​Figure11 shows that when Δτ was increased, lower and wider peaks were seen, and with decreased Δτ, higher but narrower peaks were observed. Figure ​Figure22 shows that the function fits both clinical PET and MRI AIFs well. Values of τ1 and τ2 were changed to modify the MRI-AIF and Figure ​Figure33 shows the modified MRI-AIF together with the original fitted PET-AIF, normalized to their peaks. Two AIFs have similar peak shapes but start to differ at the elimination phase as Gd-DOTA and 18F-Choline have different tissue uptake rates. Figure 1 Simulated MRI-AIFs using Parker’s population-based input function refitted with the developed function. AIF shapes with different injection durations, Δτ is shown. Figure 2 The double Butterworth convolution function used to fit (a) DSC-MRI data and (b) 18F-Choline PET data together with a plot where the timescale of PET-AIF was limited to MRI-AIF’s to show different bolus widths. Figure 3 The MRI-AIF with modified τ1 and τ2 values plotted together with the PET-AIF. The MRI-AIF peak is scaled to PET-AIF’s peak. This enables conversion of the early part of the AIFs from one modality to another even if different injection protocols are used.

Choline PET or PET/CT and Biochemical Relapse of Prostate Cancer

The increase of prostate-specific antigen (PSA) after radical retropubic prostatectomy (RP) or external beam radiotherapy (EBRT) is the most sensitive tool for detecting prostate cancer (PCa) recurrence, although this measure cannot distinguish between local, regional, or distant recurrence. The aim of this meta-analysis was to evaluate the diagnostic performance of 18F-choline and 11C-choline PET or PET/CT in detection of locoregional or distant metastases in PCa. Medline, Web of Knowledge, and Google Scholar search was carried out in order to select English-language articles dealing with diagnostic performance of both 18F-choline and 11C-choline PET for the detection of PCa recurrence after RP or EBRT. Articles were included only if absolute numbers of true-positive, true-negative, false-positive, and false-negative test results were available or derivable from the text and regarded local, lymph node, and distant metastases. Reviews, clinical reports, and editorial articles were excluded. All complete studies were re-analyzed thus performing a quantitative analysis. From the years 2000 to 2012, we found 53 complete articles that critically evaluated the role of choline PET in restaging patients with PCa recurrence. The meta-analysis was carried out and dealt with 19 selected studies (12 studies for all sites of disease, 3 for lymph node metastases, and 4 for local recurrence), with a total of 1555 patients. The meta-analysis provided a pooled sensitivity of 85.6% (95% CI: 82.9%-88.1%) and pooled specificity of 92.6% (95% CI: 90.1%-94.6%) for all sites of disease (prostatic fossa, lymph nodes, and bone), a pooled sensitivity of 75.4% (95% CI: 66.9%-82.6%) and pooled specificity of 82% (95% CI: 68.6%-91.4%) for prostatic fossa recurrence, and a pooled sensitivity of 100% (95% CI: 90.5%-100%) and pooled specificity of 81.8% (95% CI: 48.2%-97.7%) for lymph node metastases. The heterogeneity ranged between 0.00% and 88.6%. The diagnostic odds ratios were 62.123 (95% CI: 24.783-155.72), 5.869 (95% CI: 1.818-18.946), and 138.57 (95% CI: 11.27-1703.8), respectively, for all sites of disease, local recurrence, and lymph node disease. Choline PET and PET/CT represent high sensitivity and specificity techniques for the detection of locoregional and distant metastases in PCa patients with recurrence of disease. Moreover, a high diagnostic odds ratio was found for the identification of lymph node disease in patients with biochemical recurrence of PCa.

Serum tumor markers and PET/CT imaging for tumor recurrence detection

When confronted with a suspicious rise in CA 15.3 in asymptomatic breast cancer patients following primary treatment and negative or equivocal conventional imaging findings, FDG PET/CT allows assessment of the site and extent of the recurring disease with an accuracy of 83%. Both FDG PET and FDG PET/CT are superior when compared to CT alone for the purpose of recurrence detection in patients suffering from ovarian carcinoma who have completed primary therapy but demonstrate a rising serum CA-125 level. As the global accuracy of CT alone for detection of recurrence of ovarian cancer approximates 80%, CT scan should be performed upfront to identify the site of recurrence. When confronted with negative or equivocal CT findings, FDG PET alone or FDG PET/CT should be added. In patients with rising serum CEA levels that have undergone primary treatment for a colorectal carcinoma, both FDG PET and FDG PET/CT allow detection of tumor recurrence with an accuracy of 95%, well above that of CT and MRI. Available studies further suggest that FDG/PET findings will affect treatment management in 28-50% of these patients. The detection rate of both 11C-choline and 18F-choline PET and PET/CT for local, regional, and distant recurrence in prostate carcinoma patients with a biochemical recurrence increases with rising PSA value at the time of imaging and reaches about 75% in patients with PSA > 3 ng/mL. Furthermore, PET and PET/CT with [11C]- and [18F]-choline derivates may be helpful in the clinical setting for optimization of individualized treatment.

Is there the role of 18F-choline PET/CT in prostate cancer patients?

Prostate cancer is the ninth-most-common cancer in the world and the most common life-threatening cancer affecting men in the western countries. More than 80% of men will develop prostate cancer by the age of 80. Physiologically, choline is a component of cell membranes. It presents a high affinity for malignant prostate tissue. Choline, labeled with 11C or 18F is the essential part of most sensitive nuclear medicine procedure for imaging of spread of prostate cancer today. 11C-choline is preferred due to lower urinary excretion and patient exposure. Due to shorter half-life time of 11C (20 minutes), 18F-choline (half-life time of 110 minutes) is more useful for possible distribution to centers lacking on-site cyclotron. The sensitivity of 18F-choline PET/CT to detect prostate cancer preoperatively is 73%, greater than with 18F-FDG PET/CT (31%). Also, the accuracy is greater with 18F-choline PET/ CT (67%) than using 18F-FDG PET/CT (53%). The major goal of pretherapeutic imaging with 18F-choline PET/CT is detection of loco-regional and distant metastases. The exact pretherapeutic diagnosis and staging are mandatory, because the tumor treatment must be selected in strict dependence on the clinical tumor stage and risk profile. In patients with biochemical relapse after the radical prostatectomy or radiotherapy of prostate cancer, 18F-choline PET/CT represents a noninvasive, whole body study that allows disease localization. Detection sensitivity is negatively correlated with serum PSA concentration (ng/ml) and positively correlated with Gleason score. 18F-choline PET/CT is becoming the essential imaging modality in patients with prostate cancer to demonstrate spread of the disease preoperatively and to detect local and distant recurrent disease after radical prostatectomy or radiotherapy.

PET/CT in renal and bladder cancers

FDG is the most frequently used positron emission tomography probe but it has certain limitations when used in urological cancers due to its urinary elimination, which prevents the proper visualization of the bladder and kidneys. The introduction of co-registered PET and computed tomography (PET/CT) represents a major advance in technology and now become the new standard for many cancers. For the staging and surveillance of renal cell cancer, FDG PET/ CT had results that were at least as good as conventional methods, which are potentially harmful for the remained renal function. FDG-PET/CT is able to evaluate early response to sunitinib or sorafenib treatment in metastatic renal cell cancer. An early decrease in the mean glucose uptake was found in both soft and skeletal lesions after treatment, thus PET seems to be more advantageous compared with RECIST evaluation. In addition, the survival of patients with advanced renal cell cancer can be predicted by evaluating their SUVmax using FDG-PET/CT. Although urinary bladder cancer demonstrates sufficiently increased FDG uptake, primary tumors are difficult to identify due to the renal excretion of FDG. The accuracy of FDG-PET/CT in metabolically active metastases is generally higher when compared to conventional CT except for identifying small lung deposits. PET/CT with delayed images after a diuretic and oral hydration may improve detection of locally recurrent or residual UBC and could replace standard CT and bone scintigraphy in the presurgical staging and monitoring of patients with urinary bladder cancer. 18F-choline PET may be useful for staging of urinary bladder cancer in addition to FDG PET.

Feasibility of TCP-based dose painting by numbers applied to a prostate case with 18F-Choline PET imaging

IntroductionA biologically adaptive radiation treatment method to maximize the TCP is shown. Functional imaging is used to acquire a heterogeneous dose prescription in terms of Dose Painting by Numbers and to create a patient-specific IMRT plan. Method and MaterialsAdapted from a method for selective dose escalation under the guidance of spatial biology distribution, a model, which translates heterogeneously distributed radiobiological parameters into voxelwise dose prescriptions, was developed. At the example of a prostate case with 18F-choline PET imaging, different sets of reported values for the parameters were examined concerning their resulting range of dose values. Furthermore, the influence of each parameter of the linear-quadratic model was investigated. A correlation between PET signal and proliferation as well as cell density was assumed. Using our in-house treatment planning software Direct Monte Carlo Optimization (DMCO), a treatment plan based on the obtained dose prescription was generated. Gafchromic EBT films were irradiated for evaluation. ResultsWhen a TCP of 95% was aimed at, the maximal dose in a voxel of the prescription exceeded 100Gy for most considered parameter sets. One of the parameter sets resulted in a dose range of 87.1Gy to 99.3Gy, yielding a TCP of 94.7%, and was investigated more closely. The TCP of the plan decreased to 73.5% after optimization based on that prescription. The dose difference histogram of optimized and prescribed dose revealed a mean of -1.64Gy and a standard deviation of 4.02Gy. Film verification showed a reasonable agreement of planned and delivered dose. ConclusionIf the distribution of radiobiological parameters within a tumor is known, this model can be used to create a dose-painting by numbers plan which maximizes the TCP. It could be shown, that such a heterogeneous dose distribution is technically feasible.

Role of 18F-choline PET/CT in evaluation of patients with prostate carcinoma

BackgroundCholine presents a high affinity for malignant prostate tissue. It can be labelled with positron emitting 18F, and used for the evaluation of patients with prostate carcinoma by PET/CT imaging. The aim of this paper is to summarise our experience with fluoromethylcholine (18F-choline) PET/CT in patients with prostate cancer.MethodsIn 4 months we investigated the patients with histopathological (or cytological) confirmed prostate cancer. Two observers evaluated the early and late 18F-choline PET images in correlation with corresponding localising CT images and using the semiquantitative standard uptake value (SUV) calculation.ResultsThe 18F-choline PET/CT was made in 50 patients with prostate cancer. There were 18 patients after radical prostatectomy and 32 without surgery. In all patients without surgery the pathological uptake was seen in the prostate. In 14 (44 %) patients of this group there was evidence of metastatic spread in local or distant lymph nodes and/or bones. In out of 18 patients after radical prostatectomy the local recurrence was detected in 6 patients (33%) and distant metastases were present in 2 patients (10%).Conclusions18F-choline PET/CT seems to be useful imaging modality in patients with prostate carcinoma; it can demonstrate spread of the disease preoperatively and detect the local recurrence after radical prostatectomy.

SU-GG-T-499: TCP-Based Dose-Painting by Numbers at the Example of a Prostate Case with 18F-Choline PET

Purpose: A biologically adaptive radiation treatment method to maximize the TCP is shown. Functional imaging is used to acquire a heterogeneous dose prescription in terms of dose-painting by numbers and to create patient-specific IMRT plans. Method and Materials: Adapted from a method for selective dose escalation under the guidance of spatial biology distribution, a model, which translates heterogeneously distributed radiobiological parameters into voxelwise dose prescriptions, was developed. At the example of a prostate case with 18F-choline PET imaging, different sets of reported values for the parameters were examined concerning their resulting range of dose values. Furthermore, the influence of each parameter of the linear-quadratic model was investigated. A correlation between PET signal and proliferation as well as cell density was assumed. Using our in-house treatment planning software Direct Monte Carlo Optimization, a treatment plan based on the obtained dose prescription was generated. Gafchromic EBT films were irradiated for evaluation. Results: When a TCP of 99% was aimed for, the maximal dose in a voxel of the prescription exceeded 100 Gy for every considered set of parameters. With a less ambitious aim for the TCP, one of the parameter sets resulted in a dose range of 87.1 Gy to 99.3 Gy, still yielding a TCP of 94.7%. The TCP of the plan decreased to 73.5% after optimization based on that prescription. The dose difference histogram of optimized and prescribed dose revealed a mean of −1.64 Gy and a standard deviation of 4.02 Gy. Film verification showed a reasonable agreement of planned and delivered dose. Conclusion: If the distribution of radiobiological parameters within a tumor is known, this model can be used to create a dose-painting by numbers plan which maximizes the TCP. It could be shown, that such a heterogeneous dose distribution can be planned and applied.