Combined PET/CT-perfusion in patients with head and neck cancers might predict failure after radio-chemotherapy: a proof of concept study.

BACKGROUND: [18F]FDG-PET/CT imaging is broadly used in head and neck cancer (HNSCC) patients. CT perfusion (CTP) is known to provide information about angiogenesis and blood-flow characteristics in tumors. The aim of this study was to evaluate the potential relationship of FDG-parameters and CTP-parameters in HNSCC preand post-therapy and the potential prognostic value of a combined PET/CT with CTP. METHODS: Thirteen patients with histologic proven HNSCC were prospectively included. All patients underwent a combined PET/CT with integrated CTP before and after therapy. Pre- and post-therapeutic data of CTP and PET of the tumors were compared. Differences were tested using Spearman's rho test and Pearson's correlation. A p-value of p <0.05 was considered statistically significant. Correlations were calculated using Pearson's correlation. Bootstrap confidence intervals were calculated to test for additive confidence intervals. RESULTS: Three patients died due to malignancy recurrence, ten patients were free of recurrence until the end of the follow-up period. Patients with recurrent disease had significantly higher initial CTP-values compared to the recurrence-free patients: BFpre 267.4 (171.2)ml/100 mg/min, BVpre 40.9 (8.4)ml/100 mg and MTTpre 8.2 (6.1)sec. No higher SUVs initially but significantly higher TLG compared to patients without recurrence were found. Post-therapeutic PET-values differed significantly between the two groups: SUVmaxpost 6.0 (3.2), SUVmeanpost 3.6 (2.0) and TLG 21751.7 (29794.0). CONCLUSION: In our proof of concept study, combined PET/CT with integrated CTP might show complementary prognostic data pre- and post chemo-radiotherapy. CTP may be used to predict local tumor recurrence, while FDGPET/CT is still needed for whole-body staging.

Physiologic [18F]fluorodeoxyglucose uptake of floor of mouth muscles in PET/CT imaging: a problem of body position during FDG uptake?

OBJECTIVE: Assess the influence of 2 different patient positions during [18F]fluorodeoxyglucose (FDG) uptake phase on physiologic FDG accumulation of the floor of mouth (FOM) muscles. STUDY DESIGN: A prospective study design was used. METHODS: Two hundred prospectively enrolled patients were included in the study: (a) head and neck cancer (HNC) patients in supine or (b) sitting position, (c) patients with other malignant tumours in supine or (d) sitting position. An intra-individual analysis was done on patients (b) and (d) when such scans were available. Maximum standardized uptake values without correction and corrected for blood pool activity were assessed. RESULTS: The inter-individual analysis (sitting vs supine) revealed no significant differences (P = 0.17 and P = 0.56). The subgroup analysis on the patients with HNC (P = 0.56 and P = 0.15) and in patients with other malignancies (P = 0.14 and P = 0.08) revealed no significant difference; neither did the intra-individual analysis. CONCLUSIONS: The supine or sitting position during the uptake phase for FDG-positron emission tomography/computed tomography has no effect on the amount and distribution of physiologic FDG activity in the muscles of the FOM.

Discrimination and anatomical mapping of PET-positive lesions: comparison of CT attenuation-corrected PET images with coregistered MR and CT images in the abdomen.

PURPOSE: PET/MR has the potential to become a powerful tool in clinical oncological imaging. The purpose of this prospective study was to evaluate the performance of a single T1-weighted (T1w) fat-suppressed unenhanced MR pulse sequence of the abdomen in comparison with unenhanced low-dose CT images to characterize PET-positive lesions. METHODS: A total of 100 oncological patients underwent sequential whole-body (18)F-FDG PET with CT-based attenuation correction (AC), 40 mAs low-dose CT and two-point Dixon-based T1w 3D MRI of the abdomen in a trimodality PET/CT-MR system. PET-positive lesions were assessed by CT and MRI with regard to their anatomical location, conspicuity and additional relevant information for characterization. RESULTS: From among 66 patients with at least one PET-positive lesion, 147 lesions were evaluated. No significant difference between MRI and CT was found regarding anatomical lesion localization. The MR pulse sequence used performed significantly better than CT regarding conspicuity of liver lesions (p < 0.001, Wilcoxon signed ranks test), whereas no difference was noted for extrahepatic lesions. For overall lesion characterization, MRI was considered superior to CT in 40 % of lesions, equal to CT in 49 %, and inferior to CT in 11 %. CONCLUSION: Fast Dixon-based T1w MRI outperformed low-dose CT in terms of conspicuity and characterization of PET-positive liver lesions and performed similarly in extrahepatic tumour manifestations. Hence, under the assumption that the technical issue of MR AC for whole-body PET examinations is solved, in abdominal PET/MR imaging the replacement of low-dose CT by a single Dixon-based MR pulse sequence for anatomical lesion correlation appears to be valid and robust.

PET/MR imaging of bone lesions--implications for PET quantification from imperfect attenuation correction.

PURPOSE: Accurate attenuation correction (AC) is essential for quantitative analysis of PET tracer distribution. In MR, the lack of cortical bone signal makes bone segmentation difficult and may require implementation of special sequences. The purpose of this study was to evaluate the need for accurate bone segmentation in MR-based AC for whole-body PET/MR imaging. METHODS: In 22 patients undergoing sequential PET/CT and 3-T MR imaging, modified CT AC maps were produced by replacing pixels with values of >100 HU, representing mostly bone structures, by pixels with a constant value of 36 HU corresponding to soft tissue, thereby simulating current MR-derived AC maps. A total of 141 FDG-positive osseous lesions and 50 soft-tissue lesions adjacent to bones were evaluated. The mean standardized uptake value (SUVmean) was measured in each lesion in PET images reconstructed once using the standard AC maps and once using the modified AC maps. Subsequently, the errors in lesion tracer uptake for the modified PET images were calculated using the standard PET image as a reference. RESULTS: Substitution of bone by soft tissue values in AC maps resulted in an underestimation of tracer uptake in osseous and soft tissue lesions adjacent to bones of 11.2 ± 5.4% (range 1.5-30.8%) and 3.2 ± 1.7% (range 0.2-4%), respectively. Analysis of the spine and pelvic osseous lesions revealed a substantial dependence of the error on lesion composition. For predominantly sclerotic spine lesions, the mean underestimation was 15.9 ± 3.4% (range 9.9-23.5%) and for osteolytic spine lesions, 7.2 ± 1.7% (range 4.9-9.3%), respectively. CONCLUSION: CT data simulating treating bone as soft tissue as is currently done in MR maps for PET AC leads to a substantial underestimation of tracer uptake in bone lesions and depends on lesion composition, the largest error being seen in sclerotic lesions. Therefore, depiction of cortical bone and other calcified areas in MR AC maps is necessary for accurate quantification of tracer uptake values in PET/MR imaging.

Clinical impact of 18F-choline PET/CT in patients with recurrent prostate cancer.

PURPOSE: To investigate the clinical value of (18)F-fluorocholine PET/CT (CH-PET/CT) in treatment decisions in patients with recurrent prostate cancer (rPCA). METHODS: The study was a retrospective evaluation of 156 patients with rPCA and CH-PET/CT for restaging. Questionnaires for each examination were sent to the referring physicians 14-64 months after examination. Questions included information regarding initial extent of disease, curative first-line treatment, and the treatment plan before and after CH-PET/CT. Additionally, PSA values at diagnosis, after initial treatment, before CH-PET/CT and at the end of follow-up were also obtained from the questionnaires. RESULTS: Mean follow-up was 42 months. The mean Gleason score was 6.9 at initial diagnosis. Initial treatment was: radical prostatectomy in 110 patients, radiotherapy in 39, and combined prostatectomy and radiotherapy in 7. Median PSA values before CH-PET/CT and at the end of follow-up were 3.40 ng/ml and 0.91 ng/ml. PSA levels remained stable, decreased or were below measurable levels in 108 patients. PSA levels increased in 48 patients. In 75 of the 156 patients (48%) the treatment plan was changed due to the CH-PET/CT findings. In 33 patients the therapeutic plan was changed from palliative treatment to treatment with curative intent. In 15 patients treatment was changed from curative to palliative. In 8 patients treatment was changed from curative to another strategy and in 2 patients from one palliative strategy to another. In 17 patients the treatment plan was adapted. CONCLUSION: CH-PET/CT has an important impact on the therapeutic strategy in patients with rPCA and can help to determine an appropriate treatment.

Incidence and intensity of F-18 FDG uptake after vaccination with H1N1 vaccine.

OBJECTIVE: To analyze the effect of H1N1 influenza A virus vaccination in patients referred for staging or follow-up F-18 fluorodeoxyglucose (FDG) positron emission tomography/computed tomography (PET/CT) for different malignant tumors. METHOD AND MATERIALS: Medical history of all patients scheduled for FDG PET/CT during the national vaccination campaign against H1N1 was evaluated for recent vaccination. Site of injection and time between PET/CT and the date of vaccination (dTime) was determined. A difference in the maximum SUV between ipsi- and contralateral deltoid muscle or axillary lymph node of more than 0.5 was determined as positive reaction. The best cut-off dTime for still visible reaction was calculated. All patients with positive ipsilateral lymph node were clinically followed. Institutional Review Board approval was waived. RESULTS: Of 269 patients, 58 (21.5%) were vaccinated for the H1N1 within 4 weeks prior to PET/CT (mean, 14.5 ± 8.7 days). Of them, 17 (29.3%) patients had FDG-positive lymph nodes (mean SUV, 1.43 ± 1.06), with a dTime range from 1 to 14 days. Only 2 of them had no increased FDG uptake in the ipsilateral deltoid muscle. The area under the receiver operator characteristic curve revealed a strong relation between time delay (dTime) and axillary activity (AUC, 0.9; 95% confidence interval, 0.816-0.983) with a cutoff at 8 days (Youden Index). At follow-up (mean, 183 days; range, 173-196 days), no patient was found to have required treatment or signs of axillary lymphadenopathy. CONCLUSIONS: H1N1 vaccination can cause false-positive FDG PET/CT findings, when administered less than 14 days before the test, with the highest probability if the vaccination was administered less than 8 days ago. Increased FDG activity in the ipsilateral deltoid muscle is a key finding for accurate interpretation of increased FDG activity in axillary lymph nodes.

18F-FET PET/CT in advanced head and neck squamous cell carcinoma: an intra-individual comparison with 18F-FDG PET/CT.

PURPOSE: To assess the diagnostic value of O-2-fluoro-18(F)-ethyl-L-tyrosine ((18)F-FET) positron emission tomography/computed tomography (PET/CT) for patients with advanced head and neck squamous cell carcinoma compared with 18F-fluoro-2-deoxy-D-glucose ((18)F-FDG) PET/CT at initial staging and following radiochemotherapy. PROCEDURES: Thirteen patients were prospectively enrolled; each of them underwent an (18)F-FDG PET/CT and (18)F-FET PET/CT before treatment. Ten of those were scanned 10 weeks after treatment. RESULTS: Sensitivity, specificity, and accuracy for (18)F-FDG PET/CT (primary and lymph node metastases) at initial staging were 89%, 50%, and 81%. For (18)F-FET PET/CT the numbers were 70%, 90%, and 74%. Sensitivity, specificity, and accuracy for (18)F-FDG PET/CT at follow-up were 71%, 65%, and 67%. For (18)F-FET PET/CT the numbers were 29%, 100%, and 83%. Additionally, (18)F-FDG PET/CT detected a higher number of second malignancies or distant metastases. CONCLUSIONS: (18)F-FET is no substitute for (18)F-FDG. Although it is more specific, too many malignant lesions are missed due to its lower sensitivity.

Contrast-enhanced ¹8F-FDG-PET/CT for the assessment of necrotic lymph node metastases.

BACKGROUND: Cystic lymph node metastasis (CLNM) is commonly found in human papillomavirus (HPV)-associated tonsillar squamous cell carcinoma (SCC). The aim of this study was to compare the accuracy in detecting cystic lymph node metastasis from tonsillar SCC between contrast-enhanced CT, ¹8F- fluorodeoxyglucose-positron emission tomography (FDG-PET), non-enhanced ¹8F-FDG-PET/CT, and contrast-enhanced ¹8F-FDG-PET/CT. METHODS: Thirty-four patients with a tonsillar SCC undergoing a pretreatment contrast-enhanced ¹8F-FDG-PET/CT followed by a neck dissection as a standard of reference were included. The contrast-enhanced CT part, the ¹8F-FDG-PET part, the non-enhanced ¹8F-FDG-PET/CT part, and the contrast-enhanced ¹8F-FDG-PET/CT were assessed separately for correct N classification and the differentiation of N0 versus N+. RESULTS.: Contrast-enhanced ¹8F-FDG-PET/CT, non-enhanced ¹8F-FDG-PET/CT, and contrast-enhanced CT are equally accurate for correct neck staging. Regarding pN0 versus pN+, contrast-enhanced CT and contrast-enhanced ¹8F-FDG-PET/CT are superior to non-enhanced ¹8F-FDG-PET/CT (p = .017). CONCLUSION: Contrast-enhanced CT and contrast-enhanced ¹8F-FDG-PET/CT perform equally and better than non-enhanced ¹8F-FDG-PET/CT in detecting CLNM in tonsillar SCC. Therefore, in patients scheduled for ¹8F-FDG-PET/CT, we strongly suggest performing a contrast-enhanced ¹8F-FDG-PET/CT, which is not routine in most centers.

Influence of bowel preparation before 18F-FDG PET/CT on physiologic 18F-FDG activity in the intestine.

UNLABELLED: Our objective was to investigate the use of bowel preparation before (18)F-FDG PET/CT to reduce intestinal (18)F-FDG uptake. METHODS: Sixty-five patients with abdominal neoplasias were assigned either to a bowel-preparation group (n = 26) or to a native group (n = 39). (18)F-FDG activity was measured in the small intestine and the colon. RESULTS: In the 26 patients with bowel preparation, average maximal standardized uptake value (SUVmax) was 3.5 in the small intestine and 4.4 in the colon. In the 39 patients without bowel preparation, average SUVmax was 2.6 in the small intestine and 2.7 in the colon. (18)F-FDG activity impaired diagnosis in 6 patients (23%) in the bowel-preparation group and 11 patients (28%) in the native group (P = 0.5). SUVmax in the colon was significantly higher in the bowel-preparation group (P = 0.002), but SUVmax in the small intestine did not significantly differ between the 2 groups (P = 0.088). CONCLUSION: Bowel preparation increases (18)F-FDG activity in the large intestine and is therefore not useful before PET/CT.

Comparison of diffusion-weighted whole body MRI and skeletal scintigraphy for the detection of bone metastases in patients with prostate or breast carcinoma.

PURPOSE: To prospectively compare the diagnostic accuracy of diffusion-weighted whole body imaging with background whole body signal suppression (DWIBS) with skeletal scintigraphy for the diagnosis and differentiation of skeletal lesions in patients suffering from prostate or breast cancer. MATERIAL AND METHODS: A diagnostic cohort of 36 patients was included in skeletal scintigraphy and 1.5 T DWIBS MRI. Based on morphology and signal intensity patterns, two readers each identified and classified independently, under blinded conditions, all lesions into three groups: (1) malignant, (2) unclear if malignant or benign and (3) benign. Finally, for the definition of the gold standard all available imaging techniques and follow-up over a minimum of 6 months were considered. RESULTS: Overall, 45 circumscribed bone metastases and 107 benign lesions were found. DWIBS performed significantly better in detecting malignant skeletal lesions in patients with more than 10 lesions (sensitivity: 0.97/0.91) compared to skeletal scintigraphy (sensitivity: 0.48/0.42). No statistical difference could be found between DWIBS (0.58/0.33) and skeletal scintigraphy (0.67/0.58) in the sensitivity values for malignant skeletal lesions in patients with less than 5 lesions. For benign lesions, scintigraphy scored best with a sensitivity of 0.93/0.87 compared to 0.20/0.13 for DWIBS. Interobserver agreement with Cohen's kappa coefficient was calculated as 0.784 in the case of scintigraphy and 0.663 for DWIBS. CONCLUSION: With respect to staging, in prostate and breast carcinoma, the DWIBS technique is not superior to skeletal scintigraphy, but ranks equally. However, in the cases with many bone lesions, markedly more metastases could be discovered using the DWIBS technique than skeletal scintigraphy.

Positron emission tomography/computed tomography for staging and restaging of head and neck cancer: comparison with positron emission tomography read together with contrast-enhanced computed tomography.

This retrospective study aimed to describe the differences between image readings done with combined positron emission tomography/computed tomography (PET/CT) and PET read together with contrast-enhanced CT (ceCT) in patients with squamous cell carcinoma of the head and neck. In 46 patients, no differences were found between the two readings for assessing infiltration of adjacent structures (P=.63), transgression of the midline (P=.67), lymph node involvement (P=.32), and T- and N stage. PET/CT and PET read together with ceCT have comparable diagnostic yield.

Bone invasion in patients with oral cavity cancer: comparison of conventional CT with PET/CT and SPECT/CT.

PURPOSE: To prospectively compare the accuracy of helical contrast material-enhanced computed tomography (CT) with that of CT and positron emission tomography (PET) combined and CT and single photon emission CT (SPECT) combined in the detection of bone invasion in patients scheduled to undergo surgery for clinically suspected oral cavity carcinoma with possible bone invasion, with surgical results as the reference standard. MATERIALS AND METHODS: This study had local ethical committee approval, and all patients gave written informed consent. Thirty-four consecutive patients (17 men, 17 women; mean age, 64.2 years; age range, 46.0-84.6 years) who were clinically suspected of having bone invasion from oral cavity carcinoma prospectively underwent helical contrast-enhanced CT, coregistered PET/CT, and coregistered SPECT/CT. Two radiologists assessed the contrast-enhanced CT images and two nuclear medicine physicians separately assessed the PET/CT and SPECT/CT images in consensus and without knowledge of the results of other imaging tests. The presence of bone involvement as suggested with an imaging modality was compared with histologic findings in the surgical specimen. RESULTS: With histologic findings as the standard of reference, the accuracy of SPECT/CT (88% [30 of 34 patients]) was lower than that of PET/CT and contrast-enhanced CT (94% [32 of 34 patients] and 97% [33 of 34 patients], respectively). Sensitivity was highest with PET/CT (100% [12 of 12 patients]), and specificity was highest with contrast-enhanced CT (100% [22 of 22 patients]). Fluorine 18 fluorodeoxyglucose (FDG) uptake seen on two sides of the same cortical bone was not a helpful imaging pattern for better identifying bone invasion in patients without evident cortical erosion on CT scans. CONCLUSION: The assessment of cortical erosion with contrast-enhanced CT and the CT information from PET/CT are the most reliable methods for detecting bone invasion in patients with oral cavity carcinoma. FDG uptake seen on PET/CT images does not improve identification of bone infiltration.

Fluorocholine PET/CT in patients with prostate cancer: initial experience.

Institutional review board approval and written informed consent were obtained. Patients with newly diagnosed prostate cancer and patients suspected of having recurrent prostate cancer were prospectively evaluated with fluorine 18 fluorocholine (FCH) combined in-line positron emission tomography (PET) and computed tomography (CT). In 19 patients (mean age, 67 years +/- 8; range, 57-85 years), standardized uptake values of FCH in 17 different tissues were determined by using volumes of interest. In nine patients evaluated at initial staging, histologic findings of the resected prostate were compared to FCH uptake. Only small variations of physiologic tracer accumulation were measured in all organs but the kidneys. Differentiation of benign hyperplasia from cancerous prostate lesions was not possible with FCH PET/CT. However, in patients with recurrent prostate cancer, FCH PET/CT is a promising imaging modality for detecting local recurrence and lymph node metastases.

Positron emission tomography in the early follow-up of advanced head and neck cancer.

OBJECTIVE: To assess the clinical effect of an early follow-up positron emission tomography (PET) examination at the time of the first routine clinical control in patients with advanced-stage head and neck squamous cell carcinoma (HNSCC). DESIGN: Prospective, nonrandomized, case-control study. SETTING: Single referral center. PATIENTS AND INTERVENTION: A total of 26 patients (mean age, 56 years) with histologically confirmed stage III-IV HNSCC underwent PET before and approximately 6 weeks after the end of a combined treatment with radiation and chemotherapy with curative intent. The PET findings were confirmed by histologic analysis and a 6-month clinical follow-up. MAIN OUTCOME MEASURES: The presence of distant metastases, secondary synchronous cancers, and residual locoregional tissue was confirmed, and the effect on further clinical management was assessed. RESULTS: Using PET, we correctly identified residual tumor tissue, distant metastases, or a second primary tumor in 10 patients, 5 of whom had no clinical evidence of such findings. Results were true negative in 14 cases; false positive in 1; and false negative in 1. Sensitivity and specificity for follow-up PET scans were 90.9% and 93.3%, respectively. All patients with positive findings were evaluated for further treatment such as salvage surgery. CONCLUSIONS: Whole-body PET scanning approximately 6 weeks after completion of a combined treatment regimen with radiation and chemotherapy can reliably identify locoregional residual cancer and distant metastases or secondary tumors in patients with advanced-stage HNSCC and has a direct influence on management decisions.

Increased 18F-FDG uptake mimicking thyroid cancer in a patient with Hashimoto's thyroiditis.

We report the case of a 68-year-old patient with a known paravertebral malignant schwannoma, sent to us for postoperative staging. A combined whole-body PET/CT scan showed only poor (18)F-fluorodeoxyglucose uptake in the region of the primary tumor but distinct increased fluorodeoxyglucose uptake in the left and right thyroid gland. Thyroid sonography showed two hypoechogenic nodules. Ultrasound-guided fine-needle aspiration biopsy of one nodule showed oxyphil transformed cells, compatible with malignancy. Based on these findings, the patient underwent a subtotal thyroidectomy. Histopathology of the specimen revealed a chronic follicular Hashimoto's thyroiditis. This case demonstrates that Hashimoto's thyroiditis can mimic thyroid cancer in PET but also in sonography and fine-needle aspiration biopsy.

Impact of positron emission tomography on the initial staging and therapy in locoregional advanced squamous cell carcinoma of the head and neck.

OBJECTIVE: To evaluate the impact of 18F-fluoro-deoxy-glucose positron emission tomography after standard diagnostic workup in patients with advanced head and neck squamous cell carcinoma on staging and radiation treatment planning. STUDY DESIGN: Prospective controlled study. METHODS: Forty-eight patients (42 men and 6 women; mean age, 61 y; age range, 35-85 y) with histologically confirmed, advanced-stage (any T, N> or =N2 or T> or =T3, any N) mucosal head and neck squamous cell carcinoma underwent positron emission tomography. The routine workup consisting of physical examination, panendoscopy, chest x-ray film, and contrast-enhanced high-resolution helical computed tomography scan (HRCT) was used for comparison. End points were the extent of lymph node disease, distant metastases, and second primary tumors. RESULTS: In 41 of 48 patients (85%) the lymph node findings between HRCT and positron emission tomography were concordant. In three patients positron emission tomography led to an upstaging of the tumor in its N category, and in four patients positron emission tomography underestimated lymph node involvement. Positron emission tomography revealed more difficulties in delineating lymph node metastases adjacent to the primary tumor than did HRCT, but was superior for the detection of distant and contralateral lymph node metastases. Positron emission tomography suggested distant metastatic lesions in 6 of 48 patients (13%). Cytological workup confirmed distant metastases in two (4%) and second primary tumors in another two patients (4%). Positron emission tomography results were false-positive in two (4%) patients because of inflammatory changes. CONCLUSIONS: Whole-body PET is able to assess lymph node involvement, distant metastases, and second primaries in a single study. Even after a routine clinical staging, positron emission tomography leads to a change of treatment in approximately 8% of patients.