Diagnostic accuracy of contrast-enhanced FDG-PET/CT in primary staging of cutaneous malignant melanoma

Purpose: To evaluate the diagnostic accuracy of contrast-enhanced FDG-PET/CT (ce-PET/CT), PET-only, and CT-only in patients with newly diagnosed and resected cutaneous malignant melanoma. Methods: A final group of 56 patients (mean age 62years, range 23-86years; 29 women, 27 men) were staged with ce-PET/CT after resection of the primary tumour. Histopathology as well as clinical follow-up (mean 780days, range 102-1,390 days) served as the standards of reference. Differences between the staging modalities were tested for statistical significance with McNemar's test. Results: All imaging procedures provided low sensitivities in the detection of lymph nodes (sensitivity N-stage: PET/CT and PET-only 38.5%; CT-only 23.1%) and distant metastases (sensitivity M-stage: PET/CT 41.7%, PET-only 33.3%, CT-only 25.0%) in initial staging after resection of the primary tumour. No statistically significant differences were detected between the imaging procedures (p > 0.05). PET/CT resulted in an alteration in further treatment in two patients compared to PET-only and in four patients compared to CT-only. Conclusion: All imaging modalities had a low sensitivity on initial staging of patients with malignant melanoma. Thus, close patient follow-up must be considered mandator

TNM staging with FDG-PET/CT in patients with primary head and neck cancer

Purpose: PET/CT, PET+CT, and CT were compared concerning accuracies in TNM staging and malignancy detection in head and neck cancer. The impact of PET/CT compared to the other imaging modalities on therapy management was assessed. Materials and methods: Fifty-five patients with suspected head and neck primary cancer underwent whole-body FDG-PET/CT. PET/CT and PET+CT were evaluated by a nuclear medicine physician and a radiologist; CT was evaluated by two radiologists, PET by two nuclear physicians. Histopathology served as the standard of reference. Differences between the staging modalities were tested for statistical significance by McNemar's test. Results: Overall TNM-staging and T-staging with PET/CT were more accurate than PET+CT and CT alone (p < 0.05). PET/CT was marginally more accurate than CT alone in N-staging (p = 0.04); no statistically significant difference was found when compared to PET+CT for N-staging. PET/CT altered further treatment in 13 patients compared to CT only and in 7 patients compared to PET+CT. Conclusion: Combined PET/CT proved to be partly more accurate in assessing the overall TNM-stage than CT and PET+CT. These results were based on a higher accuracy concerning the T-stage, mainly in patients with metallic implants and marginally the N-stage. Therapy decisions have been influenced in a substantial number of patients. PET/CT might be considered as a first line diagnostic tool in patients with suspected primary head and neck cance

Проект производства этилена пиролизом этановой фракции

Крупнотоннажное производство этилена методом пиролиза этана.Large-tonnage ethylene production by ethylene pyrolysis

Arterial input function for quantitative dynamic contrast-enhanced MRI to diagnose prostate cancer

PURPOSEThis study aims to analyze the ability of quantitative dynamic contrast-enhanced magnetic resonance imaging (DCE-MRI) to distinguish between prostate cancer (PCa) and benign lesions in transition zone (TZ) and peripheral zone (PZ) using different methods for arterial input function (AIF) determination. Study endpoints are identification of a standard AIF method and optimal quantitative perfusion parameters for PCa detection.METHODSDCE image data of 50 consecutive patients with PCa who underwent multiparametric MRI were analyzed retrospectively with three different methods of AIF acquisition. First, a region of interest was manually defined in an artery (AIFm); second, an automated algorithm was used (AIFa); and third, a population-based AIF (AIFp) was applied. Values of quantitative parameters after Tofts (Ktrans, ve, and kep) in PCa, PZ, and TZ in the three different AIFs were analyzed.RESULTSKtrans and kep were significantly higher in PCa than in benign tissue independent from the AIF method. Whereas in PZ, Ktrans and kep could differentiate PCa (P < .001), in TZ only kep using AIFpdemonstrated a significant difference (P = .039). The correlations of the perfusion parameters that resulted from AIFm and AIFa were higher than those that resulted from AIFp, and the absolute values of Ktrans, kep, and ve were significantly lower when using AIFp. The values of quantitative perfusion parameters for PCa were similar regardless of whether PCa was located in PZ or TZ.CONCLUSIONKtrans and kep were able to differentiate PCa from benign PZ independent of the AIF method. AIFaseems to be the most feasible method of AIF determination in clinical routine. For TZ, none of the quantitative perfusion parameters provided satisfying results

Is integrated 18F-FDG PET/MRI superior to 18F-FDG PET/CT in the differentiation of incidental tracer uptake in the head and neck area?

PURPOSE:We aimed to investigate the accuracy of 18F-fluorodeoxyglucose positron emission tomography/magnetic resonance imaging (18F-FDG PET/MRI) compared with contrast-enhanced 18F-FDG PET/computed tomography (PET/CT) for the characterization of incidental tracer uptake in examinations of the head and neck.METHODS:A retrospective analysis of 81 oncologic patients who underwent contrast-enhanced 18F-FDG PET/CT and subsequent PET/MRI was performed by two readers for incidental tracer uptake. In a consensus reading, discrepancies were resolved. Each finding was either characterized as most likely benign, most likely malignant, or indeterminate. Using all available clinical information including results from histopathologic sampling and follow-up examinations, an expert reader classified each finding as benign or malignant. McNemar’s test was used to compare the performance of both imaging modalities in characterizing incidental tracer uptake.RESULTS:Forty-six lesions were detected by both modalities. On PET/CT, 27 lesions were classified as most likely benign, one as most likely malignant, and 18 as indeterminate; on PET/MRI, 31 lesions were classified as most likely benign, one lesion as most likely malignant, and 14 as indeterminate. Forty-three lesions were benign and one lesion was malignant according to the reference standard. In two lesions, a definite diagnosis was not possible. McNemar’s test detected no differences concerning the correct classification of incidental tracer uptake between PET/CT and PET/MRI (P = 0.125).CONCLUSION:In examinations of the head and neck area, incidental tracer uptake cannot be classified more accurately by PET/MRI than by PET/CT

Synovitis and bone inflammation in early rheumatoid arthritis: high-resolution multi-pinhole SPECT versus MRI

PURPOSEWe aimed to assess the relationship between bone inflammation in multi-pinhole single-photon emission computed tomography (MPH-SPECT) and synovitis detected by magnetic resonance imaging (MRI) in early rheumatoid arthritis patients. MATERIALS AND METHODSMPH-SPECT with technetium dicarboxypropanedisphosphonate (Tc-99mDPD) and 3 Tesla MRI were performed in 10 early rheumatoid arthritis patients. Eighty finger joint sites were assessed for increased osteoblastic activity using visual and region-of-interest (ROI) analysis. Presence of joint inflammation in MRI was investigated using the subscores of the rheumatoid arthritis MRI score. RESULTSTc-99mDPD uptake was increased in 38 (47.5%) and 22 (27.5%) joint sites as determined by visual and ROI analysis, respectively. A total of 32 (84.2%) sites with increased bone metabolism showed a normal MRI bone signal. The MPHSPECT uptake ratio was elevated only in the subgroup with severe synovitis (P < 0.001). CONCLUSIONIn early rheumatoid arthritis, molecular imaging with MPHSPECT detects higher rates of inflammatory bone involvement compared to MRI. Our preliminary data suggest that osteitis is related to severe synovitis

Increased x-ray attenuation in malignant vs. benign mediastinal nodes in an orthotopic model of lung cancer

PURPOSEStaging of lung cancer is typically performed with fluorodeoxyglucose-positron emission tomography-computed tomography (FDG-PET/CT); however, false positive PET scans can occur due to inflammatory disease. The CT scan is used for anatomic registration and attenuation correction. Herein, we evaluated x-ray attenuation (XRA) within nodes on CT and correlated this with the presence of malignancy in an orthotopic lung cancer model in rats.METHODS1×106 NCI-H460 cells were injected transthoracically in six National Institutes of Health nude rats and six animals served as controls. After two weeks, animals were sacrificed; lymph nodes were extracted and scanned with a micro-CT to determine their XRA prior to histologic analysis.RESULTSMedian CT density in malignant lymph nodes (n=20) was significantly higher than benign lymph nodes (n=12; P = 0.018). Short-axis diameter of metastatic lymph nodes was significantly different than benign nodes (3.4 mm vs. 2.4 mm; P = 0.025). Area under the curve for malignancy was higher for density-based lymph node analysis compared with size measurements (0.87 vs. 0.7).CONCLUSIONXRA of metastatic mediastinal lymph nodes is significantly higher than benign nodes in this lung cancer model. This suggests that information on nodal density may be useful when used in combination with the results of FDG-PET in determining the likelihood of malignant adenopath

Comparison of Template-Based Versus CT-Based Attenuation Correction for Hybrid MR/PET Scanners

Attenuation correction (AC) of cerebral PET data acquired in hybrid MR/PET scanners is still a challenge. To overcome this problem we previously proposed a correction method by obtaining template-based attenuation maps (AM) using MR and ECAT EXACT HR+ transmission scans. In the present study we investigated (a) the basic difference between template-based and CT-based AC methods and (b) their influence on reconstructed PET images. The data of 11 subjects undergoing 18FDG imaging in the Siemens 3T MR-BrainPET scanner were used. Additionally, from all participants a CT scan of the whole head was acquired at the same day. These CT images were transformed to CT-based AMs. They were filtered by a 3D Gaussian kernel with 3 mm (BrainPET resolution) filter width, which was considered as reference. Comparisons between both AMs (CT-based and template-based) were performed by estimating the Dice coefficients D and calculating the numbers of true positive, true negative and false negative voxels. The BrainPET emission data were reconstructed with both AMs ( AMCT3mm and AMTemplate). All reconstructed PET images were scaled to standardized uptake values (SUVs) and normalized to the MNI brain for using the AAL-VOI Atlas analysis. Correlation plots with regression equation, coefficients of determination R2 and relative differences (RD) between AMCT3mm and the AMTemplate were derived. The fraction of the overall true positive voxels averaged over the 11 subjects was 80.4 ±7.5% for AMTemplate compared to AMCT3mm ( Dbone = 0.63 ±0.08; Dsoft - tissue = 0.85 ±0.08; Dair = 0.79 ±0.04). A misclassification of bone as soft tissue and vice versa was evident in the comparison. The correlation plot of all VOIs considered (1,276 values) showed a mean R2 of 0.964 and a slope of 1.02. A mean RD of 1.33 ±0.95% ( min = - 0.12%, max = 2.85%) was found. The template-based AC method proposed by our group shows considerable differences in comparison to the higher resolution CT-based AM with respect to the Dice coefficients, in particular in the classification of bone and soft tissue. However, this has no major influence on the reconstructed 18FDG PET data