An EANM position paper on the application of artificial intelligence in nuclear medicine

Artificial intelligence (AI) is coming into the field of nuclear medicine, and it is likely here to stay. As a society, EANM can and must play a central role in the use of AI in nuclear medicine. In this position paper, the EANM explains the preconditions for the implementation of AI in NM and takes position.

Application of artificial intelligence in nuclear medicine and molecular imaging: a review of current status and future perspectives for clinical translation

Artificial intelligence (AI) will change the face of nuclear medicine and molecular imaging as it will in everyday life. In this review, we focus on the potential applications of AI in the field, both from a physical (radiomics, underlying statistics, image reconstruction and data analysis) and a clinical (neurology, cardiology, oncology) perspective. Challenges for transferability from research to clinical practice are being discussed as is the concept of explainable AI. Finally, we focus on the fields where challenges should be set out to introduce AI in the field of nuclear medicine and molecular imaging in a reliable manner.

Is C-11 Methionine PET an alternative to 18-F FDG-PET for identifying recurrent laryngeal cancer after radiotherapy?

OBJECTIVE

18F FDG-PET is superior to other imaging techniques in revealing residual laryngeal cancer after radiotherapy. Unfortunately, its specificity is low, due to FDG uptake in inflammation and in anaerobic conditions. PET imaging with the amino acid-based radiopharmaceutical C11-methionine (MET) should be less influenced by post-radiation conditions. The aim of this study was to investigate the potential of MET in diagnosing recurrent laryngeal cancer after radiotherapy as compared to 18F-FDG.

METHODS

Forty-eight patients with a clinical suspicion of local residual disease at least 3 months after completion of radiotherapy or chemoradiotherapy for a T2-4 laryngeal carcinoma, along with an indication for direct laryngoscopy, were included. They received MET-PET and FDG-PET prior to the direct laryngoscopy. One senior nuclear medicine physician assessed both the FDG-PET and MET-PET images visually for the degree of abnormal uptake. The gold standard was a biopsy-proven recurrence 12 months after PET. The nuclear physician had no access to the medical charts and was blinded to the results of the other PET. Sensitivity, specificity and positive and negative predictive value were calculated.

RESULTS

The sensitivity of FDG was 77.3% and the specificity 56.0% after the conservative reading, with these values equalling 54.5% and 76.0% for MET. The positive predictive value of FDG was 60.7% and the negative predictive value 73.7%. The PPV of MET was 66.7%, and the NPV was 65.5%. The McNemar test within diseased (sensitivity comparison) shows a p-value of 0.125, and the McNemar test within non-diseased (specificity comparison) shows a P-value of 0.180.

CONCLUSION

MET-PET is not superior to FDG-PET in terms of identifying recurrent laryngeal cancer.

18F-DCFPyL PET/CT in the Detection of Prostate Cancer at 60 and 120 Minutes: Detection Rate, Image Quality, Activity Kinetics, and Biodistribution

There is increasing interest in PET/CT with prostate-specific membrane antigen (PSMA) tracers for imaging of prostate cancer because of the higher detection rates of prostate cancer lesions than with PET/CT with choline. For ⁶⁸Ga-PSMA-11 tracers, late imaging at 180 min after injection instead of imaging at 45-60 min after injection improves the detection of prostate cancer lesions. For ¹⁸F-DCFPyL, improved detection rates have recently been reported in a small pilot study. In this study, we report the effects of PET/CT imaging at 120 min after injection of ¹⁸F-DCFPyL in comparison to images acquired at 60 min after injection in a larger clinical cohort of 66 consecutive patients with histopathologically proven prostate cancer. Methods: Images were acquired 60 and 120 min after injection of ¹⁸F-DCFPyL. We report the positive lesions specified for anatomic locations (prostate, seminal vesicles, local lymph nodes, distant lymph nodes, bone, and others) at both time points by visual analysis, the image quality at both time points, and a semiquantitative analysis of the tracer activity in both prostate cancer lesions as well as normal tissues at both time points. Results: Our data showed a significantly increasing uptake of ¹⁸F-DCFPyL between 60 and 120 min after injection in 203 lesions characteristic for prostate cancer (median, 10.78 vs. 12.86, P < 0.001, Wilcoxon signed-rank test). By visual analysis, 38.5% of all patients showed more lesions using images at 120 min after injection than using images at 60 min after injection, and in 9.2% a change in TNM staging was found. All lesions seen on images 60 min after injection were also visible on images 120 min after injection. A significantly better mean signal-to-noise ratio of 11.93 was found for images acquired 120 min after injection (P < 0.001, paired t test; signal-to-noise ratio at 60 min after injection, 11.15). Conclusion:¹⁸F-DCFPyL PET/CT images at 120 min after injection yield a higher detection rate of prostate cancer characteristic lesions than images at 60 min after injection. Further studies are needed to elucidate the best imaging time point for ¹⁸F-DCFPyL.

Total Body Metabolic Tumor Response in ALK Positive Non-Small Cell Lung Cancer Patients Treated with ALK Inhibition

BACKGROUND

In ALK-positive advanced NSCLC, crizotinib has a high response rate and effectively increases quality of life and survival. CT measurement of the tumor may insufficiently reflect the actual tumor load changes during targeted therapy with crizotinib. We explored whether 18F-FDG PET measured metabolic changes are different from CT based changes and studied the impact of these changes on disease progression.

METHODS

18F-FDG PET/CT was performed prior to and after 6 weeks of crizotinib treatment. Tumor response on CT was classified with RECIST 1.1, while 18F-FDG PET response was assessed according to the 1999 EORTC recommendations and PERCIST criteria. Agreement was assessed using McNemars test. During follow-up, patients received additional PET/CT during crizotinib treatment and second generation ALK inhibition. We assessed whether PET was able to detect progression earlier then CT.

RESULTS

In this exploratory study 15 patients were analyzed who were treated with crizotinib. There was a good agreement in the applicability of CT and 18F-FDG PET/CT using the EORTC recommendations. During first line crizotinib and subsequent second line ALK inhibitors, PET was able to detect progression earlier then CT in 10/22 (45%) events of progression and in the others disease progression was detected simultaneously.

CONCLUSION

In advanced ALK positive NSCLC PET was able to detect progressive disease earlier than with CT in nearly half of the assessments while both imaging tests performed similar in the others.

An exploratory study of volumetric analysis for assessing tumor response with (18)F-FAZA PET/CT in patients with advanced non-small-cell lung cancer (NSCLC)

BACKGROUND

Hypoxia is associated with resistance to chemotherapy and radiotherapy and is randomly distributed within malignancies. Characterization of changes in intratumoral hypoxic regions is possible with specially developed PET tracers such as (18)F-fluoroazomycin arabinoside ((18)F-FAZA) while tumor metabolism can be measured with 2-deoxy-2-[(18)F]fluoro-D-glucose ((18)F-FDG). The purpose of this study was to study the effects of chemotherapy on (18)F-FAZA and (18)F-FDG uptake simultaneously in non-small-cell lung cancer (NSCLC) patients

METHODS

At baseline and after the second chemotherapy cycle, both PET/CT with (18)F-FDG and (18)F-FAZA was performed in seven patients with metastasized NSCLC. (18)F-FAZA and (18)F-FDG scans were aligned with deformable image registration using Mirada DBx. The primary tumors were contoured, and on the (18)F-FDG scan, volumes of interest (VOI) were drawn using a 41 % adaptive threshold technique. Subsequently, the resulting VOI was transferred to the (18)F-FAZA scan. (18)F-FAZA maximum tumor-to-background (T/Bgmax) ratio and the fractional hypoxic volume (FHV) were assessed. Measurements were corrected for partial volume effects. Finally, a voxel-by-voxel analysis of the primary tumor was performed to assess regional uptake differences.

RESULTS

In the primary tumor of all seven patients, median (18)F-FDG standard uptake value (SUVmax) decreased significantly (p = 0.03). There was no significant decrease in (18)F-FAZA uptake as measured with T/Bgmax (p = 0.24) or the FHV (p = 0.35). Additionally, volumetric voxel-by-voxel analysis showed that low hypoxic tumors did not significantly change in hypoxic status between baseline and two cycles of chemotherapy, whereas highly hypoxic tumors did. Individualized volumetric voxel-by-voxel analysis revealed that hypoxia and metabolism were not associated before and after 2 cycles of chemotherapy.

CONCLUSIONS

Tumor hypoxia and metabolism are independent dynamic events as measured by (18)F-FAZA PET and (18)F-FDG PET, both prior to and after treatment with chemotherapy in NSCLC patients.

Clinical impact of 11C-Choline PET/CT in selection and outcome of salvage cryoablation in patients with recurrent prostate cancer after radiotherapy

276

Background: Salvage cryoablation is an effective but toxic treatment for local recurrent prostate cancer after primary radiotherapy. To assess the location of recurrent prostate cancer, an 11C-choline PET/CT can be used. We studied the clinical impact of 11C-choline PET/CT on the choice for and the results of salvage cryoablation. Methods: A total of 141 patients with a biochemical recurrence (BCR according to ASTRO-Phoenix criteria) after radiotherapy, and thus candidates for salvage cryoablation, were included. Patients were re-staged with an 11C-choline PET/CT, complementary prostate biopsies, when indicated a pelvic lymph node dissection and/or additional imaging. Change in choice of therapy was defined as major (no salvage cryoablation because of metastases or lack of local recurrence on PET/CT), minor (local salvage treatment was performed, but different technique of after additional diagnostics) or none (salvage cryoablation was performed). The impact of selection of patients for cryoablation with PET/CT on outcome was measured by time from cryoablation to BCR (according to Astro-Phoenix), first distant metastasis and start of hormonal therapy. Results: In 71 of 141 patients (51%) a change in therapy was implemented because of the result of 11C-choline PET/CT. A major impact was observed in 48 (34%) patients. In 83 patients, a salvage cryoablation was performed (59%). 18% of this group showed no PSA response. Of the remaining patients with PSA response, 37% developed a BCR after mean 25.7 months. 47% of patients are still in remission after a mean follow-up of 43 months. In 16 of 83 patients (19%) metastases were proven after mean 55.4 months (SD 26.3). 15 patients started with hormonal therapy, mean 29.5 months (SD 20.1) after cryoablation. Conclusions: 11C-choline PET/CT showed a significant impact on selection for salvage cryoablation. The choice for local salvage therapy was abandoned in 34% of patients. Of the men who underwent a salvage cryoablation, 47% stayed free of biochemical recurrence during mean 43 months follow-up.

Impact of fasting on (18)F-fluorocholine gastrointestinal uptake and detection of lymph node metastases in patients with prostate cancer

Background

¹⁸F-fluorocholine PET/CT is used to detect lymph node metastases in prostate cancer patients. Physiological ¹⁸F-fluorocholine in the gastrointestinal tract, especially in the intestines, may interfere with the detection of malignant lymph nodes. Fasting is frequently proposed in literature; however, scientific support is lacking. This study aims to determine the impact of fasting on ¹⁸F-fluorocholine uptake in the gastrointestinal tract.

Methods

Eighty patients were studied, 40 fasted for at least 6 h prior to ¹⁸F-fluorocholine administration while the other 40 did not fast. ¹⁸F-fluorocholine uptake pattern and intensity were evaluated in the intestine near the abdominal aorta and four regions near the iliac arteries. ¹⁸F-fluorocholine intensity was also measured in the liver, pancreas, stomach and spleen.

Findings

No statistically significant differences were found in ¹⁸F-fluorocholine uptake in the gastrointestinal tract between the fasting and non-fasting group.

Conclusions

Fasting for 6 h has no effect on ¹⁸F-fluorocholine uptake in the gastrointestinal tract. Therefore, no effects on the detection of malignant lymph nodes are expected, and fasting is not recommended in our opinion.

Effectiveness of an (18)F-FDG-PET based strategy to optimize the diagnostic trajectory of suspected recurrent laryngeal carcinoma after radiotherapy: The RELAPS multicenter randomized trial

PURPOSE

The purpose of this study is to evaluate the efficacy of (18)F-FDG-PET as first-line diagnostic investigation, prior to performing a direct laryngoscopy with biopsy under general anesthesia, in patients suspected of recurrent laryngeal carcinoma after radiotherapy.

PATIENTS AND METHODS

150 patients suspected of recurrent T2-4 laryngeal carcinoma at least two months after prior (chemo)radiotherapy with curative intent for resectable disease were randomized to direct laryngoscopy (CWU: conventional workup strategy) or to (18)F-FDG-PET only followed by direct laryngoscopy if PET was assessed 'positive' or 'equivocal' (PWU: PET based workup strategy), to compare the effectiveness of these strategies. Primary endpoint was the number of indications for direct laryngoscopies classified as unnecessary based on absence of recurrence, both on direct laryngoscopy and on six month follow up. Safety endpoints comprised resectability of recurrent lesions and completeness of surgical margins following salvage laryngectomy.

RESULTS

Intention-to-treat analyses were performed on all randomized patients (CWU: n=74, PWU: n=76). Tumor recurrence was similar in both groups: 45 patients (30%; 21 CWU, 24 PWU) within six months. In 53 patients in the CWU arm (72%, 95% CI: 60-81) unnecessary direct laryngoscopies were performed compared to 22 in the PWU arm (29%, 95% CI: 19-40) (p<0·0001). The percentage of salvage laryngectomies (resectability) and positive surgical margins were similar between CWU and PWU (81%, 63% respectively, p=0·17, and 29%, 7%, respectively, p=0.20). The prevalence of the combination of local unresectability and positive margins is in the CWU group 24% and in the PWU group 8%. No difference (p=0.32) in disease specific survival between both groups was found.

CONCLUSION

In patients with suspected laryngeal carcinoma after radiotherapy, PET as the first diagnostic procedure can reduce the need for direct laryngoscopy by more than 50% without jeopardizing quality of treatment.

Evaluation of elastix-based propagated align algorithm for VOI- and voxel-based analysis of longitudinal (18)F-FDG PET/CT data from patients with non-small cell lung cancer (NSCLC)

Background

Deformable image registration allows volume of interest (VOI)- and voxel-based analysis of longitudinal changes in fluorodeoxyglucose (FDG) tumor uptake in patients with non-small cell lung cancer (NSCLC). This study evaluates the performance of the elastix toolbox deformable image registration algorithm for VOI and voxel-wise assessment of longitudinal variations in FDG tumor uptake in NSCLC patients.

Methods

Evaluation of the elastix toolbox was performed using ¹⁸F-FDG PET/CT at baseline and after 2 cycles of therapy (follow-up) data in advanced NSCLC patients. The elastix toolbox, an integrated part of the IMALYTICS workstation, was used to apply a CT-based non-linear image registration of follow-up PET/CT data using the baseline PET/CT data as reference. Lesion statistics were compared to assess the impact on therapy response assessment. Next, CT-based deformable image registration was performed anew on the deformed follow-up PET/CT data using the original follow-up PET/CT data as reference, yielding a realigned follow-up PET dataset. Performance was evaluated by determining the correlation coefficient between original and realigned follow-up PET datasets. The intra- and extra-thoracic tumors were automatically delineated on the original PET using a 41% of maximum standardized uptake value (SUV_max) adaptive threshold. Equivalence between reference and realigned images was tested (determining 95% range of the difference) and estimating the percentage of voxel values that fell within that range.

Results

Thirty-nine patients with 191 tumor lesions were included. In 37/39 and 12/39 patients, respectively, thoracic and non-thoracic lesions were evaluable for response assessment. Using the EORTC/SUV_max-based criteria, 5/37 patients had a discordant response of thoracic, and 2/12 a discordant response of non-thoracic lesions between the reference and the realigned image. FDG uptake values of corresponding tumor voxels in the original and realigned reference PET correlated well (R²=0.98). Using equivalence testing, 94% of all the voxel values fell within the 95% range of the difference between original and realigned reference PET.

Conclusions

The elastix toolbox impacts lesion statistics and therefore therapy response assessment in a clinically significant way. The elastix toolbox is therefore not applicable in its current form and/or standard settings for PET response evaluation. Further optimization and validation of this technique is necessary prior to clinical implementation.

Electronic supplementary material

The online version of this article (doi:10.1186/s13550-015-0089-z) contains supplementary material, which is available to authorized users.

FDG PET/CT: EANM procedure guidelines for tumour imaging: version 2.0

The purpose of these guidelines is to assist physicians in recommending, performing, interpreting and reporting the results of FDG PET/CT for oncological imaging of adult patients. PET is a quantitative imaging technique and therefore requires a common quality control (QC)/quality assurance (QA) procedure to maintain the accuracy and precision of quantitation. Repeatability and reproducibility are two essential requirements for any quantitative measurement and/or imaging biomarker. Repeatability relates to the uncertainty in obtaining the same result in the same patient when he or she is examined more than once on the same system. However, imaging biomarkers should also have adequate reproducibility, i.e. the ability to yield the same result in the same patient when that patient is examined on different systems and at different imaging sites. Adequate repeatability and reproducibility are essential for the clinical management of patients and the use of FDG PET/CT within multicentre trials. A common standardised imaging procedure will help promote the appropriate use of FDG PET/CT imaging and increase the value of publications and, therefore, their contribution to evidence-based medicine. Moreover, consistency in numerical values between platforms and institutes that acquire the data will potentially enhance the role of semiquantitative and quantitative image interpretation. Precision and accuracy are additionally important as FDG PET/CT is used to evaluate tumour response as well as for diagnosis, prognosis and staging. Therefore both the previous and these new guidelines specifically aim to achieve standardised uptake value harmonisation in multicentre settings.

First clinical results of (D)-18F-Fluoromethyltyrosine (BAY 86-9596) PET/CT in patients with non-small cell lung cancer and head and neck squamous cell carcinoma

(D)-(18)F-fluoromethyltyrosine (d-(18)F-FMT), or BAY 86-9596, is a novel (18)F-labeled tyrosine derivative rapidly transported by the l-amino acid transporter (LAT-1), with a faster blood pool clearance than the corresponding l-isomer. The aim of this study was to demonstrate the feasibility of tumor detection in patients with non-small cell lung cancer (NSCLC) or head and neck squamous cell cancer (HNSCC) compared with inflammatory and physiologic tissues in direct comparison to (18)F-FDG.

METHODS

18 patients with biopsy-proven NSCLC (n = 10) or HNSCC (n = 8) were included in this Institutional Review Board-approved, prospective multicenter study. All patients underwent (18)F-FDG PET/CT scans within 21 d before d-(18)F-FMT PET/CT. For all patients, safety and outcome data were assessed.

RESULTS

No adverse reactions were observed related to d-(18)F-FMT. Fifty-two lesions were (18)F-FDG-positive, and 42 of those were malignant (34 histologically proven and 8 with clinical reference). Thirty-two of the 42 malignant lesions were also d-(18)F-FMT-positive, and 10 lesions had no tracer uptake above the level of the blood pool. Overall there were 34 true-positive, 8 true-negative, 10 false-negative, and only 2 false-positive lesions for d-(18)F-FMT, whereas (18)F-FDG was true-positive in 42 lesions, with 10 false-positive and only 2 false-negative, resulting in a lesion-based detection rate for d-(18)F-FMT and (18)F-FDG of 77% and 95%, respectively, with an accuracy of 78% for both tracers. A high d-(18)F-FMT tumor-to-blood pool ratio had a negative correlation with overall survival (P = 0.050), whereas the (18)F-FDG tumor-to-blood pool ratio did not correlate with overall survival.

CONCLUSION

d-(18)F-FMT imaging in patients with NSCLC and HNSCC is safe and feasible. The presented preliminary results suggest a lower sensitivity but higher specificity for d-(18)F-FMT over (18)F-FDG, since there is no d-(18)F-FMT uptake in inflammation. This increased specificity may be particularly beneficial in areas with endemic granulomatous disease and may improve clinical management. Further clinical investigations are needed to determine its clinical value and relevance for the prediction of survival prognosis.

Small-animal PET with a σ-ligand, 11C-SA4503, detects spontaneous pituitary tumors in aged rats

Pituitary tumors are often detected only after death or at late stages of the disease when they are macroadenomas with a low surgical cure rate. Spontaneous pituitary tumors occur in rats over 1 y of age. In an ongoing study of changes in σ-1 agonist binding related to aging, several of our rats developed such tumors. The aim of the current study was to assess the kinetics of (11)C-SA4503 ((11)C-labeled 1-[2-(3,4-dimethoxyphenthyl)]-4-(3-phenylpropyl)-piperazine dihydrochloride) in tumor and brain and to evaluate the utility of this tracer in the detection of pituitary tumors.

METHODS

Small-animal PET scans of the brain region of male Wistar Hannover rats (age, 18-32 mo) were acquired using the σ-1 agonist tracer (11)C-SA4503. The time-dependent uptake of (11)C in the entire brain, tumor or normal pituitary, and thyroid was measured. A 2-tissue-compartment model was fitted to the PET data, using metabolite-corrected plasma radioactivity as the input function.

RESULTS

Pituitary tumors showed up as bright hot spots in the scans. The total distribution volume (VT) of the tracer was significantly higher in the tumor than in the normal pituitary. Surprisingly, a higher VT was also seen in the brain and thyroid tissue of animals with pituitary tumors than in healthy rats. The increase in VT in the brain and thyroid was not related to a change in nondisplaceable binding potential (BPND) but rather to an increase in the partition coefficient (K1/k2) of (11)C-SA4503. The increase in VT in the tumor on the other hand was accompanied by a significant increase in BPND. Western blotting analysis indicated that pituitary tumors overexpressed σ-1 receptors.

CONCLUSION

The overexpression of σ-1 receptors in spontaneous pituitary tumors is detected as an increase in uptake and BPND of (11)C-SA4503. Therefore, this tracer may have promise for the detection of pituitary adenomas, using PET.

Application of (99m)Technetium-HYNIC(tricine/TPPTS)-Aca-Bombesin(7-14) SPECT/CT in prostate cancer patients: a first-in-man study

RATIONALE

The peptide bombesin (BBN) and its derivatives exhibit high binding affinity for the gastrin-releasing peptide receptor (GRPR), which is highly expressed in prostate cancer. We used the BBN-based radiopharmaceutical (99m)Technetium-HYNIC(tricine/TPPTS)-Aca-Bombesin(7-14) ((99m)Tc-HABBN) to perform a first-in-man clinical pilot study to evaluate the feasibility of (99m)Tc-HABBN SPECT/CT for detection of prostate cancer in patients.

METHODS

Eight patients with biopsy-proven prostate cancer who were scheduled for either radical prostatectomy or external beam radiotherapy underwent (99m)Tc-HABBN scintigraphy and SPECT/CT prior to treatment. Serial blood samples were taken to assess blood radioactivity and to determine in vivo metabolic stability. Clinical parameters were measured and reported side effects, if present, were recorded. Prostate cancer specimens of all patients were immunohistochemically stained for GRPR.

RESULTS

(99m)Tc-HABBN was synthesized with high radiochemical yield, purity and specific activity. There were no significant changes in clinical parameters, and there were no adverse or subjective side effects. Low metabolic stability was observed, as less than 20% of (99m)Tc-HABBN was intact after 30 min. Immunohistochemical staining for GRPR was observed in the prostate cancer specimens in all patients. (99m)Tc-HABBN scintigraphy and SPECT/CT did not detect prostate cancer in patients with proven disease.

CONCLUSIONS

(99m)Tc-HABBN SPECT/CT for visualization of prostate cancer is safe but hampered by an unexpected low in vivo metabolic stability in man. The difference between the excellent in vitro stability of (99m)Tc-HABBN in human serum samples determined in our previous study regarding (99m)Tc-HABBN and the low in vivo metabolic stability determined in this study, is striking. This issue warrants further study of peptide-based radiopharmaceuticals.

PET imaging of tumor hypoxia using 18F-fluoroazomycin arabinoside in stage III-IV non-small cell lung cancer patients

Tumor hypoxia hampers the efficacy of radiotherapy because of its increased resistance to ionizing radiation. The aim of the present study was to estimate the potential added clinical value of the specific hypoxia tracer (18)F-fluoroazomycin arabinoside ((18)F-FAZA) over commonly used (18)F-FDG in the treatment of advanced-stage non-small cell lung cancer (NSCLC).

METHODS

Eleven patients with stage III or stage IV NSCLC underwent (18)F-FDG and (18)F-FAZA PET before chemoradiotherapy. The maximum standardized uptake value (SUVmax) was used to depict (18)F-FDG uptake, and the tumor-to-background (T/B) ratio and tumor fractional hypoxic volume (FHV) were used to quantify hypoxia. The spatial correlation between (18)F-FDG and (18)F-FAZA uptake values was investigated using voxel-based analysis. Partial-volume correction was applied.

RESULTS

All 11 patients showed clear uptake of (18)F-FAZA in the primary tumor. However, different patterns of (18)F-FDG and (18)F-FAZA uptake distributions were observed and varied widely among different tumors. No significant correlation was observed between (18)F-FDG SUVmax and (18)F-FAZA T/B ratio (P = 0.055). The median FHV of 1.4 was 48.4% (range, 5.0-91.5). A significant positive correlation was found between the (18)F-FAZA T/B ratio and FHV of 1.4 (P < 0.001). There was no correlation between the lesion size and FHV or between the (18)F-FDG SUVmax and FHV. The pattern of tumoral (18)F-FDG uptake was rather homogeneous, whereas (18)F-FAZA uptake was more heterogeneous, suggesting that (18)F-FAZA identifies hypoxic areas within metabolically active areas of tumor. A significant correlation between (18)F-FDG SUVmax and lesion size (P = 0.002) was observed.

CONCLUSION

(18)F-FAZA PET imaging is able to detect heterogeneous distributions of hypoxic subvolumes out of homogeneous (18)F-FDG background in a clinical setting. Therefore, (18)F-FAZA might be considered a tool for guiding dose escalation to the hypoxic fraction of the tumor.

Abstract 2662: Effects of chemotherapy on tumor hypoxia measured with 18-F-FAZA PET/CT and compared to FDG-PET/CT in advanced non-small-cell lung cancer (NSCLC)

Introduction

Hypoxia in tumors is associated with resistance to chemotherapy. 18-F-FAZA is a PET tracer developed to characterize intratumoral hypoxic regions. Tumor metabolism is measured with 18-F-FDG PET. Goal of this study is to investigate hypoxic changes in relation to metabolic alterations in patients with advanced NSCLC during chemotherapy.

Methods

PET-CT with 18-F-FDG and 18-F-FAZA tracers were used prior to the first cycle and after the second cycle of chemotherapy. Volumes of interest were manually drawn on visual inspection. For FAZA, mean and maximum (max) tumor to background (FAZAT/B) ratios, and for FDG, SUVmax and SUVmean, were calculated. Measurements were corrected for partial volume using a NEMA image quality phantom. The fractional hypoxic volume, defined as the tumor fraction with a T/B ratio above 1.2 was calculated. The hypoxic and metabolic distribution within the primary tumor was studied with skewness and kurtosis. Differences between baseline and second measurement were calculated with the Wilcoxon signed rank test.

Results

FDG and FAZA scans were performed in 9 patients. Median FAZAT/Bmax was 2.8 (1.9-4.7) at baseline and 3.3 (1.3-5.5) and after 2 cycles, respectively, while SUVmax was 14.8 (5.8-32.5) at baseline and 14.6 (1.9-24.9) after 2 cycles. Fractional hypoxic volume was 78% (17-100%) at baseline and 74% (0-100%) after 2 cycles of therapy. No significant changes in hypoxia or metabolism were observed during chemotherapy. Hypoxic and metabolic heterogeneity within the primary tumor remained unchanged. At baseline skewness was different between FDG and FAZA (p=0.02). After 2 cycles this difference did not persist (p=0.31). There was no difference at baseline or after 2 cycles in kurtosis between FDG and FAZA. Tumor response measured with CT was 2 PR, 5 SD and 2 PD.

Conclusion

In this exploratory study the fractional hypoxic volume and the heterogeneity of hypoxic and metabolic areas remained unchanged during chemotherapy. The intratumoral difference in FAZA and FDG distribution changed from baseline to that after 2 cycles of chemotherapy.

Citation Format: Gerald S.M.A. Kerner, Vikram R. Bollineni, Thijo J.N. Hiltermann, Jan Pruim, Harry J.M. Groen. Effects of chemotherapy on tumor hypoxia measured with 18-F-FAZA PET/CT and compared to FDG-PET/CT in advanced non-small-cell lung cancer (NSCLC). [abstract]. In: Proceedings of the 104th Annual Meeting of the American Association for Cancer Research; 2013 Apr 6-10; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2013;73(8 Suppl):Abstract nr 2662. doi:10.1158/1538-7445.AM2013-2662

11C-choline PET/CT in selection of patients for salvage cryoablation in recurrent prostate cancer

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Background: 11C-choline PET/CT has proven to be a sensitive technique for re-staging after radiation therapy (RT). The aim of this study was to analyze the clinical impact of 11C-choline-PET/CT in the selection of patients with biochemical recurrence (BCR) after RT for salvage cryoablation of the prostate. Methods: This prospective study was conducted between November 2006 and February 2012 on patients considered as candidates for salvage cryoablation. 74 patients, mean age 69.2 years, median – 70.3 years (range 49-79), who were being followed up after RT for histological proven prostate cancer (according to ASTRO-Phoenix) were included. Until 2009 we used PET/CT fusion, but from 2009 all patients were examined with an integrated PET/CT system. After receiving 400 MBq 11C-choline intravenously, a whole body scan was made. As reference we used biopsy-proven histology from site of suspicion, confirmative imaging modalities (bonescan, CT) or clinical follow-up. PSA doubling time and velocity was calculated. Results: According to the PET/CT results, 40 (54%) patients had a local recurrence, 20 (27%) had regional/distant metastases and 14 (19%) had a negative scan. The positive PET findings were proved by histology from prostate biopsies and/or pelvic lymph node dissections in 63% of cases. Considering PET/CT results: 50/74 (68%) patients received cryoablation, for 24/74 (32%) treatment was changed (active surveillance or androgen deprivation therapy). Conclusions: 11C-choline-PET/CT could be useful for the selection of patients with BCR after RT for salvage cryoablation of the prostate. 11C-choline-PET/CT was decisive and led to therapy change in 32% of cases. [Table: see text]

Correlation of [11C]choline PET-CT with time to treatment and disease-specific survival in men with recurrent prostate cancer after radical prostatectomy

AIM

Radiotherapy following radical prostatectomy should be considered in men with high risk features who have a life expectancy of more than 10 years. So far no effect on prostate cancer specific survival has been proven by 3 randomized controlled trials (RCTs) on adjuvant radiotherapy. At present the optimal timing of radiotherapy is not defined. Identifying the site of recurrence is difficult at low PSA levels. [11C]choline PET-CT studies in biochemical recurrent prostate cancer after prostatectomy show a higher frequency of (false) negative cases compared to restaging after EBRT. It is uncertain if this reflects low volume of disease and/or low grade as biopsies fail to prove recurrent cancer in 50% of cases. We followed the clinical course of men with recurrent prostate cancer after radical prostatectomy and investigated treatment and survival. PET-CT data were correlated with clinical data, PSA kinetics and disease specific and overall survival. We also studied relative survival comparing an age matched group from the Central Dutch Statistical Office (CBS).

METHODS

Sixty-four patients underwent [11C]choline PET-CT on PSA relapse. All patients were initially treated with radical prostatectomy and reached PSA nadir of <0.1 ng/mL. Recurrent disease was defined as PSA increase <0.2 ng/mL after nadir. Patients were either treated with watchful waiting, salvage radiotherapy and/or androgen deprivation therapy based on individual assessments by the treating urologists. Statistic: χ2, log-rank and Mann-Whitney-U tests were used to compare the [11C] choline PET/CT groups.

RESULTS

The 64 patients had median PSA of 1.4 ng/mL. Median follow-up period of patients was 50 (6-124) months. Ten patients died during the course of follow-up of which 5 due to metastasized disease. No significant differences were seen in age, time to recurrence, total PSA at recurrence and PET-CT results. Patients with abnormal PET had higher PSAVel (median 3.09 ng/mL/yr versus 10.17, P=0.002) and shorter PSADT (med 4.83 months vs. 0.53, P=0.016). Median time to treatment was significantly lower in the PET-CT negative group. Age of patients at death from the whole group did not differ from the age of death in an age matched group. Disease specific survival was significantly higher in the PET-CT negative group (P=0.05).

CONCLUSION

[11C]choline PET-CT showed that a negative PET/CT correlated with a higher disease specific survival and a lower treatment rate in men with a biochemical recurrence after radical prostatectomy. Overall survival of the total group was equal to the age matched cohort emphasizing the limited effect of a biochemical recurrent prostate cancer on overall survival. The optimum timing (adjuvant or early salvage) must be answered in running trials before adjuvant RT is used as standard of care.

Impact of total PSA, PSA doubling time and PSA velocity on detection rates of 11C-Choline positron emission tomography in recurrent prostate cancer

PURPOSE

To evaluate the effect of total PSA (tPSA) and PSA kinetics on the detection rates of (11)C-Choline PET in patients with biochemical recurrence (BCR) after radical prostatectomy (RP) or external beam radiotherapy (EBRT).

METHODS

We included 185 patients with BCR after RP (PSA >0.2 ng/ml) or after EBRT (ASTRO definition). After injection of 400 MBq 11C-Choline i.v., a scan was made using the ECAT HR + PET camera with CT fusion images or Siemens mCT PET/CT. Biopsy-proven histology, confirmative imaging (CT or bone scan) and/or clinical follow-up (PSA) were used as composite reference. Statistical analysis was performed using PASW Statistics 18.

RESULTS

11C-Choline PET was positive in 124/185 cases (65%) (in 22/61 (36%) after RP, 102/124 (82%) after EBRT). In 79 patients a local recurrence was identified, and 45 patients showed locoregional metastases on PET/CT. In 20 cases a proven false-negative PET scan was observed. Positive PET scans were confirmed by histology in 87/124 (70%) cases, by confirmatory imaging in 34/124 (28%) and by clinical follow-up after salvage treatment in 3 (2%) cases. The ROC analysis to detect a recurrence showed significant difference in area under the curve (AUC) of tPSA 0.721(p < 0.001) and PSA velocity 0.730 (p < 0.001). PSA doubling time showed no significant difference with an AUC of 0.542 (p = 0.354). Detection rates are <50% in tPSA <2 ng/ml and/or PSA velocity <1 ng/ml/year.

CONCLUSIONS

Total serum PSA and PSA velocity have significant effect on the detection rates of 11C-Choline PET/CT in men with a BCR after RP or EBRT.

[11C]choline PET for the intraprostatic tumor characterization and localization in recurrent prostate cancer after EBRT

AIM

This study focuses on the potential role of [11C]choline positron emission tomography (PET) for the intraprostatic tumor characterization and localization in recurrent prostate cancer after EBRT.

METHODS

This retrospective study was conducted in patients who were being followed up after EBRT for histological proven prostate cancer. We selected the patients with a local recurrence by [11C]choline PET/CT fusion. The results of PET were compared with the results of histology and with clinical follow-up.

RESULTS

Forty-two patients with a local recurrence suggested by PET were included in this study. According to PET results: of the 42 patients, 15 (36%) had a focal recurrence, 27 (64%) showed a diffuse recurrence. The overall concordance of PET with histology concerning detection of recurrence was 76% (32 patients had positive PET results and positive biopsies). We confirmed the local recurrence as visualized by PET in 37/42 (88%) patients using a composite reference with histology and clinical follow up after local salvage treatment. The concordance of the intraprostatic distribution of the tumor with PET with histology from transrectal prostate biopsies (median biopsies 7, range 4-12) was 47% (7/15) in unilateral cases and 41% (11/27) in bilateral cases. No significant differences were seen between the 2 groups in serum PSA at time of PET (P=0.509) and SUV (P=0.739) using Student's t-test.

CONCLUSION

Intraprostatic characterization of recurrent prostate cancer after EBRT with 11C-choline PET is feasible at present but shows a moderate concordance with routine transrectal prostate biopsies. The accuracy is too low for the routine use of this modality in the present scenario.

Prognostic impact of hexokinase and glucose transporter expressions and clinicopathologic features related to F-18-FDG uptake in esophageal cancer

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Background: Elucidation of prognostic predictors based on biological viability may be useful for a better detection of patients with a high risk of relapse or death from esophageal cancer.

Methods: Maximum standardized uptake values (SUVmax) were measured in the preoperative 18F-FDG positron emission tomography (PET) scans of 47 patients who had a radical esophageal resection without previous treatment. Expression levels of hexokinase-II (HK-II), glucose transporter I (GLUT-I), hypoxia inducible factor-1α (HIF-Iα), vascular endothelial growth factor (VEGF), p53 and the proliferative activity (MIB-I score) were determined immunohistochemically on paraffin-embedded tumor tissue. Correlations and survival functions were calculated to identify independent correlations between FDG-uptake and prognostic expression levels.

Results: High HK-II expression was significantly correlated with reduced SUVmax values (p= 0.002) and HK-II expression was significant higher among adenocarcinomas than squamous cell carcinomas (36/37 vs. 5/9, p= 0.004). The five years survival was significant better for patients with SUVmax≤ 3 in their primary tumors (75% vs. 25%) and a lymph node (LN) ratio ≤0.20 (40% vs. 6%). There were also significant disease free survival benefits for different expression rates of GLUT-I, p53 and MIB (log rank p= 0.03, p= 0.03 and p= 0.04 respectively) in patients with a lymph node ratio >0.20.

Conclusions: FDG-uptake and LN ratio are strong prognostic predictors in patients with esophageal cancer. The level of GLUT-I and p53 expression and the MIB score may be useful prognostic markers that provide information about tumor aggressiviness in esophageal cancer.

Plasma thymus and activation-regulated chemokine as an early response marker in classical Hodgkin's lymphoma

BACKGROUND

Plasma thymus and activation-regulated chemokine is a potential biomarker for classical Hodgkin's lymphoma. To define its value as a marker to monitor treatment response, we correlated serial plasma thymus and activation-regulated chemokine levels with clinical response in newly diagnosed and relapsed classical Hodgkin's lymphoma patients.

DESIGN AND METHODS

Plasma was collected from 60 (39 early stage and 21 advanced stage) newly diagnosed classical Hodgkin's lymphoma patients before, during, and after treatment, and from 12 relapsed patients before and after treatment. Plasma thymus and activation-regulated chemokine levels were determined by enzyme-linked immunosorbent assay and were related to pre-treatment metabolic tumor volume, as measured by quantification of 2-[18F]fluoro-2-deoxyglucose positron emission tomography images, and to treatment response.

RESULTS

Baseline plasma thymus and activation-regulated chemokine levels correlated with stage of disease and bulky disease, and more closely with metabolic tumor volume. Response to treatment was observed among 38 of 39 early stage and 19 of 21 advanced stage patients. Reduction in plasma thymus and activation-regulated chemokine to normal range levels could be observed as early as after one cycle of chemotherapy in all responsive patients, while plasma levels remained elevated during and after treatment in the 3 non-responsive patients. Plasma thymus and activation-regulated chemokine was elevated in all 12 relapsed patients at time of relapse and remained elevated after salvage treatment in the 4 non-responsive patients.

CONCLUSIONS

Baseline plasma thymus and activation-regulated chemokine levels correlate with classical Hodgkin's lymphoma tumor burden and serial levels correlate with response to treatment in patients with classical Hodgkin's lymphoma.

Reduction of artefacts caused by hip implants in CT-based attenuation-corrected PET images using 2-D interpolation of a virtual sinogram on an irregular grid

Purpose

Metallic prosthetic replacements, such as hip or knee implants, are known to cause strong streaking artefacts in CT images. These artefacts likely induce over- or underestimation of the activity concentration near the metallic implants when applying CT-based attenuation correction of positron emission tomography (PET) images. Since this degrades the diagnostic quality of the images, metal artefact reduction (MAR) prior to attenuation correction is required.

Methods

The proposed MAR method, referred to as virtual sinogram-based technique, replaces the projection bins of the sinogram that are influenced by metallic implants by a 2-D Clough-Tocher cubic interpolation scheme performed in an irregular grid, called Delaunay triangulated grid. To assess the performance of the proposed method, a physical phantom and 30 clinical PET/CT studies including hip prostheses were used. The results were compared to the method implemented on the Siemens Biograph mCT PET/CT scanner.

Results

Both phantom and clinical studies revealed that the proposed method performs equally well as the Siemens MAR method in the regions corresponding to bright streaking artefacts and the artefact-free regions. However, in regions corresponding to dark streaking artefacts, the Siemens method does not seem to appropriately correct the tracer uptake while the proposed method consistently increased the uptake in the underestimated regions, thus bringing it to the expected level. This observation is corroborated by the experimental phantom study which demonstrates that the proposed method approaches the true activity concentration more closely.

Conclusion

The proposed MAR method allows more accurate CT-based attenuation correction of PET images and prevents misinterpretation of tracer uptake, which might be biased owing to the propagation of bright and dark streaking artefacts from CT images to the PET data following the attenuation correction procedure.

Value of EUS in Determining Curative Resectability in Reference to CT and FDG-PET: The Optimal Sequence in Preoperative Staging of Esophageal Cancer?

BACKGROUND

F-fluorodeoxyglucose positron emission tomography (FDG-PET) in the optimal sequence in staging esophageal cancer has not been investigated adequately.

METHODS

The staging records of 216 consecutive operable patients with esophageal cancer were reviewed blindly. Different staging strategies were analyzed, and the likelihood ratio (LR) of each module was calculated conditionally on individual patient characteristics. A logistic regression approach was used to determine the most favorable staging strategy.

RESULTS

Initial EUS results were not significantly related to the LRs of initial CT and FDG-PET results. The positive LR (LR+) of EUS-fine-needle aspiration (FNA) was 4, irrespective of CT and FDG-PET outcomes. The LR+ of FDG-PET varied from 13 (negative CT) to 6 (positive CT). The LR+ of CT ranged from 3-4 (negative FDG-PET) to 2-3 (positive FDG-PET). Age, histology, and tumor length had no significant impact on the LRs of the three diagnostic tests.

CONCLUSIONS

This study argues in favor of PET/CT rather than EUS as a predictor of curative resectability in esophageal cancer. EUS does not correspond with either CT or FDG-PET. LRs of FDG-PET were substantially different between subgroups of negative and positive CT results and vice versa.

Correlation of 11c-choline PET-CT with time to treatment and disease-specific survival in men with recurrent prostate cancer after radical prostatectomy

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Background: Restaging with PET-CT in biochemical recurrent prostate cancer after prostatectomy shows a higher frequency of (false) negative cases compared to restaging after EBRT. It is uncertain if this reflects low volume of disease and/or low grade as biopsies fail to prove recurrent cancer in 50% of cases. We followed the clinical course of men with recurrent prostate cancer (PCa) after radical prostatectomy and investigated treatment and survival. PET-CT data were correlated with clinical data, PSA kinetics and disease specific and overall survival. We also studied relative survival comparing an age matched group from the Central Dutch Statistical Office (CBS).

Methods: 64 patients underwent 11C-Choline PET-CT on PSA relapse. All patients were initially treated with radical prostectomy and reached PSA nadir of <0.1ng/mL. Recurrent disease was defined as PSA <0.4ng/mL after nadir. Patients were either treated with watchful waiting, adjuvant radiotherapy and/ or androgen deprivation therapy based on individual assesments by the treating urologists. Chi-square, log-rank and Mann-Whitney-U tests were used to study this population

Results: The 64 patients had median PSA of 1.4ng/mL. Median follow-up period of patients was 50 (6–124) months. Ten patients died during the course of follow-up of which 5 due to metastasized PCa. No significant differences were seen in age, time to recurrence, total PSA at recurrence and PET-CT results. Patients with abnormal PET had higher PSAVel (median 3.09 ng/mL/yr vs 10.17, p= 0.002) and and shorter PSADT (med 4.83 mo vs 0.53, p= 0.016). Median time to treatment was significantly lower in the PET-CT negative group. Age of patients at death from the whole group did not differ from the age of death in an age matched group. Disease specific survival was significantly higher in the PET-CT negative group (p0.05).

Conclusions: A negative 11C-Choline PET-CT correlated with a higher disease specific survival and a lower treatment rate. Overall survival of the group was equal to the age matched cohort.

No significant financial relationships to disclose.

18F-FLT-PET for detection of rectal cancer

PURPOSE

This pilot study was undertaken to examine the ability of (18)F-3'-fluoro-3'-deoxy-l-thymidine positron emission tomography ((18)F-FLT-PET)to detect rectal cancer, to identify pathologic lymph nodes and to determine the accuracy of tumour length estimation in comparison with computer tomography (CT).

METHODS

Nine patients with biopsy proven rectal cancer underwent CT and (18)F-FLT-PET scanning prior to short-term pre-operative radiotherapy (5×5Gy). Within 10 days after the start of radiotherapy a surgical resection was performed. Tumour lengths and regional lymph node visualisation on both imaging modalities were compared with pathology findings.

RESULTS

All tumours were visible on CT. (18)F-FLT-PET visualised 7 out of 9 tumours (78%). The pathology-based tumours lengths correlated better with CT as compared to FLT-PET(r=0.91, p<0.01). (18)F-FLT-PET was not able to visualise pathologic lymph nodes. However, CT identified all patients with pathologic lymph nodes.

CONCLUSION

Primary rectal cancer can be visualised by (18)F-FLT-PET in the majority of cases but not in all. However, (18)F-FLT-PET was not able to identify pathologic lymph nodes. Therefore, we conclude that (18)F-FLT-PET has limited value for the detection of pathologic lymph nodes and tumour delineation in rectal cancer.

18F-FDG PET during stereotactic body radiotherapy for stage I lung tumours cannot predict outcome: a pilot study

Purpose

¹⁸F-Fluorodeoxyglucose positron emission tomography (FDG PET) has been used to assess metabolic response several months after stereotactic body radiotherapy (SBRT) for early-stage non-small cell lung cancer. However, whether a metabolic response can be observed already during treatment and thus can be used to predict treatment outcome is undetermined.

Methods

Ten medically inoperable patients with FDG PET-positive lung tumours were included. SBRT consisted of three fractions of 20 Gy delivered at the 80% isodose at days 1, 6 and 11. FDG PET was performed before, on day 6 immediately prior to administration of the second fraction of SBRT and 12 weeks after completion of SBRT. Tumour metabolism was assessed semi-quantitatively using the maximum standardized uptake value (SUV_max) and SUV_70%.

Results

After the first fraction, median SUV_max increased from 6.7 to 8.1 (p = 0.07) and median SUV_70% increased from 5.7 to 7.1 (p = 0.05). At 12 weeks, both median SUV_max and median SUV_70% decreased by 63% to 3.1 (p = 0.008) and to 2.5 (p = 0.008), respectively.

Conclusion

SUV increased during treatment, possibly due to radiation-induced inflammation. Therefore, it is unlikely that ¹⁸F-FDG PET during SBRT will predict treatment success.

Monitoring response to antiangiogenic therapy in non-small cell lung cancer using imaging markers derived from PET and dynamic contrast-enhanced MRI

With antiangiogenic agents, tumor shrinkage may be absent, despite survival benefit. The present study assessed the predictive value of molecular imaging for the identification of survival benefit during antiangiogenic treatment with bevacizumab and erlotinib in patients with advanced non-small cell lung cancer.

METHODS

Patients were evaluated using an imaging protocol including CT, 18F-FDG PET, H2(15)O PET, and dynamic contrast-enhanced MRI to derive measurements on tumor size, glucose metabolism, perfusion, and microvascular permeability. The percentage change in imaging parameters after 3 wk of treatment as compared with baseline was calculated and correlated with progression-free survival (PFS).

RESULTS

Forty-four patients were included, and 40 underwent CT and 18F-FDG PET at both time points. Complete datasets, containing all imaging modalities, were available for 14 patients. Bevacizumab and erlotinib treatment resulted in decreased metabolism, perfusion, and tumor size. A decrease in standardized uptake value or tumor perfusion of more than 20% at week 3 was associated with longer PFS (9.7 vs. 2.8 mo, P=0.01, and 12.5 vs. 2.9 mo, P=0.009, respectively). Whole-tumor Ktrans (the endothelial transfer constant) was not associated with PFS, but patients with an increase of more than 15% in the SD of tumor Ktrans values-that is, an increase in regions with low or high Ktrans values-after 3 wk had shorter PFS (2.3 vs. 7.0 mo, P=0.008). A partial response, according to the response evaluation criteria in solid tumors (RECIST), at week 3 was also associated with prolonged PFS (4.6 vs. 2.9 mo, P=0.017). However, 40% of patients with a partial response as their best RECIST response still had stable disease at week 3. In these cases tumor perfusion was already decreased and Ktrans heterogeneity showed no increase, indicating that the latter parameters seem to be more discriminative than RECIST at the 3-wk time point.

CONCLUSION

PET and dynamic contrast-enhanced MRI were able to identify patients who benefit from bevacizumab and erlotinib treatment. Molecular imaging seems to allow earlier response evaluation than CT.

PET/CT and radiotherapy in prostate cancer

Radiotherapy is one of the corner stone treatments for patients with prostate cancer. Especially for locally advanced tumors radiotherapy +/- adjuvant androgen deprivation treatment is standard of care. This brings up the need for accurate assessment of extra prostatic tumor growth and/or the presence of nodal metastases for selection of the optimal radiation dose and treatment volume. Morphological imaging like transrectal ultra sound, computed tomography (CT) and magnetic resonance imaging (MRI) are routinely used but are limited in their accuracy in detecting extra prostatic extension and nodal metastases. In this article we present a structured review of the literature on positron emission tomography (PET)/CT and radiotherapy in prostate cancer patients with emphasis on: 1) the pretreatment assessment of extra prostatic tumor extension, nodal and distant metastases; 2) the intraprostatic tumor characterization and radiotherapy treatment planning; and 3) treatment evaluation and the use of PET/CT in guidance of salvage treatment. PET/CT is not an appropriate imaging technique for accurate T-staging of prostate cancer prior to radiotherapy. Although macroscopic disease beyond the prostatic capsule and into the periprostatic fat or in seminal vesicle is often accurately detected, the microscopic extension of prostate cancer remains undetected. Choline PET/CT holds a great potential as a single step diagnostic procedure of lymph nodes and skeleton, which could facilitate radiotherapy treatment planning. At present the use of PET/CT for treatment planning in radiotherapy is still experimental. Choline PET based tumor delineation is not yet standardized and different segmentation-algorithms are under study. However, dose escalation using dose-painting is feasible with only limited increases of the doses to the bladder and rectum wall. PET/CT using either acetate or choline is able to detect recurrent prostate cancer after radiotherapy but stratification of patients for any local salvage treatment has not been addressed in the current literature.

Changes in nutritional status and dietary intake during and after head and neck cancer treatment

BACKGROUND

The purpose of this study was to test whether nutritional status of patients with head and neck cancer changes during and after treatment.

METHODS

Nutritional status (including body weight, lean mass, and fat mass) and dietary intake were assessed in 29 patients with head and neck cancer. Patients were assessed 1 week before, and 1 and 4 months after treatment (radiotherapy, either alone or combined with chemotherapy or surgery).

RESULTS

During treatment, body weight (-3.6 ± 5.3 kg; p = .019) and lean mass (-2.43 ± 2.81 kg; p = .001) significantly declined. Patients with sufficient intake (≥35 kcal and ≥1.5 grams protein/kg body weight) lost less body weight and lean mass than patients with insufficient intake (mean difference, -4.0 ± 1.9 kg; p = 0.048 and -2.1 ± 1.0 kg; p = .054, respectively). After treatment, only patients with sufficient intake gained body weight (2.3 ± 2.3 kg) and lean mass (1.2 ± 1.3 kg).

CONCLUSION

Patients with head and neck cancer fail to maintain or improve nutritional status during treatment, despite sufficient intake.

First-line erlotinib and bevacizumab in patients with locally advanced and/or metastatic non-small-cell lung cancer: a phase II study including molecular imaging

BACKGROUND

Both bevacizumab and erlotinib have clinical activity in non-small-cell lung cancer (NSCLC). Preclinical data suggest synergistic activity.

PATIENTS AND METHODS

Chemonaive patients with stage IIIb or IV non-squamous NSCLC were treated with bevacizumab 15 mg/kg every 3 weeks and erlotinib 150 mg daily until progression. Primary end point was non-progression rate (NPR) at 6 weeks. Tumor response was measured with computed tomography, 2-[fluorine-18]fluoro-2-deoxy-D-glucose (FDG-PET) and dynamic contrast-enhanced magnetic resonance imaging (DCE-MRI). KRAS and EGFR mutations were assessed in tumor samples.

RESULTS

Forty-seven patients were included. Median follow-up was 15.2 months. NPR at 6 weeks was 75%. Median progression-free survival (PFS) was 3.8 [95% confidence interval (CI) 2.3-5.4] months and median overall survival (OS) was 6.9 (95% CI 5.5-8.4) months. Toxicity was mainly mild. The presence of KRAS (n = 10) or EGFR mutations (n = 5) did not influence outcome. After 3 weeks of treatment, >20% decrease in standard uptake value as measured with positron emission tomography predicted for longer PFS (9.7 versus 2.8 months; P = 0.01) and >40% decrease in K(trans) as assessed by DCE-MRI did not predict for longer PFS.

CONCLUSIONS

First-line treatment with bevacizumab and erlotinib in stage IIIb/IV NSCLC resulted in an NPR of 75%. OS was however disappointing. Early response evaluation with FDG-PET is the best predictive test for PFS.

Detection of cervical metastases with (11)C-tyrosine PET in patients with squamous cell carcinoma of the oral cavity or oropharynx: A comparison with (18)F-FDG PET

BACKGROUND

A disadvantage of 2-[(18)F]fluoro-2-deoxy-D-glucose ((18)F-FDG) positron emission tomography (PET) in head and neck cancer is that (18)F-FDG uptake is not specific to malignant tissue. To provide an alternative, radiolabeled amino acids such as L-1-[(11)C]-tyrosine ((11)C-TYR), were introduced because these are less avidly metabolized by inflammatory cells.

METHODS

In this prospective study, we compared both (11)C-TYR PET and (18)F-FDG PET performance in detecting cervical metastases in 27 patients with a squamous cell carcinoma (SCC) of oral cavity or oropharynx.

RESULTS

(11)C-TYR PET sensitivity, specificity, and accuracy for detecting nodal metastases were 33%, 100%, and 81%, respectively. With respect to (18)F-FDG PET, these figures were 67%, 97%, and 89%, respectively. Neck metastases not detected by (11)C-TYR PET were camouflaged by high tracer uptake by salivary glands.

CONCLUSIONS

Because of bilateral accumulation of (11)C-TYR in salivary glands, (11)C-TYR PET is not suitable to replace (18)F-FDG PET in staging SCC of oral cavity and oropharynx.

A systematic review on the role of FDG-PET/CT in tumour delineation and radiotherapy planning in patients with esophageal cancer

PURPOSE

FDG-PET/CT has proven to be useful in the staging process of esophageal tumours. This review analysed the role of FDG-PET/CT in tumour delineation and radiotherapy planning in comparison with CT alone among patients with esophageal cancer. Thereby we focused on the detection of the primary tumour and lymph nodes by FDG-PET/CT, changes in target volume (TV) delineation based on FDG-PET/CT and its validity, changes in inter- and intra-observer variability in TV delineation, consequences for radiotherapy treatment planning with regard to either target volumes or organs at risk and finally on the validation of FDG-PET/CT-based TVs in terms of treatment outcome.

METHODS

A literature search was performed in MEDLINE and Cochrane library databases for studies concerning the current value of FDG-PET/CT in tumour detection and delineation and radiotherapy-planning procedures among patients with esophageal cancer. Both prospective and retrospective studies were included.

RESULTS

Fifty publications met the eligibility criteria, of which 19 were review papers and one was a case report. The remaining 30 publications reported on the results of original studies. FDG-PET was able to identify most primary tumours, with a sensitivity and specificity for the detection of metastatic lymph nodes of 30-93% and 79-100%. The use of FDG-PET/CT resulted in changes of target volumes, and consequently in changes in treatment planning. However, evidence supporting the validity of the use of FDG-PET/CT in the tumour delineation process is very limited. Only three studies reported a significant positive correlation between FDG-PET-based tumour lengths and pathological findings. There were two studies that tested the influence of FDG-PET/CT to the inter- and intra-observer variability. One of them found a significant decrease in inter- and intra-observer variability, while the others did not. Furthermore, there are no studies demonstrating the use of PET/CT in terms of improved locoregional control or survival.

CONCLUSION

Since the literature is very limited standard implementation of FDG-PET/CT into the tumour delineation process for radiation treatment seems unjustified and needs further clinical validation first.