Lactate Dehydrogenase Prior to Transarterial Hepatic Chemoperfusion Predicts Survival and Time to Progression in Patients with Uveal Melanoma Liver Metastases.

PURPOSE: To assess serum lactate dehydrogenase (LDH) as a pretreatment prognostic factor in patients with uveal melanoma liver metastases treated with transarterial hepatic chemoperfusion (THC). MATERIALS AND METHODS: 56 patients (48 % male, median age: 63.5 years) underwent a median of 4 THC sessions. Kaplan-Meier for median overall survival (OS) and time to hepatic progression (TTP; 95 %CI) in months and Cox proportional hazards model for uni- (UVA) & multivariate analyses (MVA) for hazard ratio (HR) evaluation were calculated. RESULTS: The median OS was 9.4 months. The pretreatment LDH value before 1st THC was the strongest OS predictor with 19.8 months for normal (≦ 280 units per liter (U/L)), 9.7 for intermediate (> 280-< 1000 U/L), and 3.84 months for high (≧ 1000 U/L) LDH. LDH significantly predicted a median TTP with 8 months, 4 months, and 1 month for normal, intermediate, and high LDH, respectively. UVA revealed intermediate (16.5) and high (77.3) LDH, bilirubin > the upper limit of normal (ULN) (2.89), alkaline phosphatase > 1.5 ULN (6.8), leukocytes > ULN (4.2), gamma-glutamyl transferase (GGT) > ULN (7), extrahepatic metastases (1.8) and liver lesions ≥ 5 cm (3.6) as significant predictors for worse OS. MVA confirmed intermediate (5) and high (27.1) LDH, bilirubin (5.7), GGT (2.9), and tumor size ≥ 5 cm (3.7) as significant independent predictors for worse OS. Patients with decreasing vs. increasing LDH > 10 % between 1st and 2nd THC (median: 38 days) survived longer (14.6 vs. 4.3 months) and progressed later (7 months vs. 1 month). CONCLUSION: Elevated pretreatment serum LDH is an essential and robust OS and TTP predictor, potentially allowing for the identification of patients benefiting most from transarterial hepatic chemoperfusion. KEY POINTS: · Pretherapeutic LDH is the most reliable prognosticator for OS and TTP. · Therapy-related LDH decrease > 10 % between 1st and 2nd THC had prolonged OS and TTP. · Lower Values of LDH, bilirubin, gamma-glutamyl transferase, and tumor size are independent pretherapeutic predictors for longer OS. · Extrahepatic metastases do not have an independent influence on overall survival. CITATION FORMAT: · Ludwig J, Haubold J, Heusner T et al. Lactate Dehydrogenase Prior to Transarterial Hepatic Chemoperfusion Predicts Survival and Time to Progression in Patients with Uveal Melanoma Liver Metastases. Fortschr Röntgenstr 2021; 193: 683 - 691.

Impact of dual-energy CT prior to radioembolization (RE).

BACKGROUND: Depiction of the exact arterial liver anatomy as well as identifying potential extrahepatic non-target vessels is crucial for a successful preparation of radioembolization (RE). PURPOSE: To compare the diagnostic impact of dual-energy computed tomography (DECT) to digital subtraction angiography prior to RE. MATERIAL AND METHODS: DECT was applied in 46 patients with hepatocellular carcinoma (HCC) prior to RE. Eighty kV DE as well as reconstructed 120 kV equivalent DE datasets were evaluated in comparison to correlating digital subtraction angiography (DSA) datasets. Two radiologists evaluated in consensus the delineation of liver arteries and extrahepatic non-target vessels utilizing a 4-point scale (4 = excellent delineation; 1 = non-diagnostic). In addition, the arterial vascularization of liver segment IV was evaluated and classified: signal-to-noise ratio (SNR) and contrast-to-noise ratio (CNR; liver arteries to adjacent liver tissue) were obtained via ROI analysis. RESULTS: Both imaging techniques (DECT, DSA) enabled high-quality assessment of all analyzed liver arteries. Out of the two CT datasets, 80 kVp-DE datasets offered superior delineation of the right gastric artery (3.5 ± 0.7 vs. 2.5 ± 0.5), the vascularization of segment IV (3.9 ± 0.2 vs. 3.3 ± 0.5) as well as potential extrahepatic non-target vessels (3.9 ± 0.1 vs. 3.3 ± 0.5). In accordance to the results of the qualitative analysis, 80 kVp-DE datasets also yielded higher SNR (34.84 vs. 29.31) and CNR (28.29 vs. 21.8) values in comparison to the 120 kVp datasets. CONCLUSION: Eighty kVp DECT enables a significantly better assessment of the arteries of the upper abdomen for therapy planning in comparison to correlating 120 kVp datasets. This may allow for identification of potential extrahepatic non-target vessels and assessment of target volume for therapy planning prior to DSA.

Thoracic staging in lung cancer: prospective comparison of 18F-FDG PET/MR imaging and 18F-FDG PET/CT.

UNLABELLED: Therapeutic decisions in non-small cell lung cancer (NSCLC) patients depend on the tumor stage. PET/CT with (18)F-FDG is widely accepted as the diagnostic standard of care. The purpose of this study was to compare a dedicated pulmonary (18)F-FDG PET/MR imaging protocol with (18)F-FDG PET/CT for primary and locoregional lymph node staging in NSCLC patients using histopathology as the reference. METHODS: Twenty-two patients (12 men, 10 women; mean age ± SD, 65.1 ± 9.1 y) with histopathologically confirmed NSCLC underwent (18)F-FDG PET/CT, followed by (18)F-FDG PET/MR imaging, including a dedicated pulmonary MR imaging protocol. T and N staging according to the seventh edition of the American Joint Committee on Cancer staging manual was performed by 2 readers in separate sessions for (18)F-FDG PET/CT and PET/MR imaging, respectively. Results from histopathology were used as the standard of reference. The mean and maximum standardized uptake value (SUV(mean) and SUV(max), respectively) and maximum diameter of the primary tumor was measured and compared in (18)F-FDG PET/CT and PET/MR imaging. RESULTS: PET/MR imaging and (18)F-FDG PET/CT agreed on T stages in 16 of 16 of patients (100%). All patients were correctly staged by (18)F-FDG PET/CT and PET/MR (100%), compared with histopathology. There was no statistically significant difference between (18)F-FDG PET/CT and (18)F-FDG PET/MR imaging for lymph node metastases detection (P = 0.48). For definition of thoracic N stages, PET/MR imaging and (18)F-FDG PET/CT were concordant in 20 of 22 patients (91%). PET/MR imaging determined the N stage correctly in 20 of 22 patients (91%). (18)F-FDG PET/CT determined the N stage correctly in 18 of 22 patients (82%). The mean differences for SUV(mean) and SUV(max) of NSCLC in (18)F-FDG PET/MR imaging and (18)F-FDG PET/CT were 0.21 and -5.06. These differences were not statistically significant (P > 0.05). The SUV(mean) and SUV(max) measurements derived from (18)F-FDG PET/CT and (18)F-FDG PET/MR imaging exhibited a high correlation (R = 0.74 and 0.86, respectively; P < 0.0001). Size measurements showed an excellent correlation between (18)F-FDG PET/MR imaging and (18)F-FDG PET/CT (R = 0.99; P < 0.0001). The lower and upper limits of agreement between (18)F-FDG PET/CT and (18)F-FDG PET/MR imaging using Bland-Altman analysis were -2.34 to 3.89 for SUV(mean), -7.42 to 4.40 for SUV(max), and -0.59 to 0.83 for the tumor size, respectively. CONCLUSION: (18)F-FDG PET/MR imaging using a dedicated pulmonary MR imaging protocol, compared with (18)F-FDG PET/CT, does not provide advantages in thoracic staging in NSCLC patients.

Diagnostic accuracy of ultrasound, ¹8F-FDG-PET/CT, and fused ¹8F-FDG-PET-MR images with DWI for the detection of cervical lymph node metastases of HNSCC.

OBJECTIVE: This study aimed to compare (18)F-fluorodesoxyglucose positron emission tomography/MRI ((18)F-FDG-PET-MRI) fusion images, including diffusion-weighted imaging (DWI), (18)F-FDG-PET/CT, and ultrasound (US) regarding their performance in nodal staging of patients with head and neck squamous cell carcinoma (HNSCC). MATERIALS AND METHODS: Eighteen patients prospectively underwent ultrasound examination, (18)F-FDG- PET/CT, and MRI before oral tumor resection and bilateral neck dissection. PET data sets were fused with contrast-enhanced T1-weighted MR images. The sensitivity, specificity, positive predictive value (PPV), negative predictive value (NPV), and accuracy for nodal detection were calculated for all the imaging modalities. Furthermore, the accuracy of the correct N-staging was calculated for all methods. Detailed histopathology served as the standard of reference. RESULTS: The sensitivity, specificity, PPV, NPV, and accuracy for detection of lymph node metastases were 63, 99, 86, 96, and 95 % for ultrasound; 30, 97, 56, 92, and 90 % for (18)F-FDG-PET/CT; 52, 96, 59, 94, and 91 % for (18)F-FDG-PET-MRI; and 53, 97, 67, 95, and 92 % for (18)F-FDG-PET-MRI plus DWI, respectively. There was no significant difference in the diagnostic accuracy for lymph node metastasis detection between (18)F-FDG-PET-MRI and (18)F-FDG-PET/CT (p = 0.839) and between (18)F-FDG-PET-MRI plus DWI and (18)F-FDG-PET/CT (p = 0.286), respectively. US was significantly more accurate than (18)F-FDG-PET/CT (p = 0.009), whereas no significant difference was seen between (18)F-FDG-PET-MRI and US (p = 0.223) or (18)F-FDG-PET-MRI plus DWI and US (p = 0.115). The nodal stage was correctly rated by (18)F-FDG-PET-MRI in eight patients, (18)F-FDG-PET-MRI plus DWI in nine patients, US in 12 patients, and (18)F-FDG-PET/CT in five out of 18 patients. CONCLUSION: Software-based fusion of (18)F-FDG-PET-MRI and (18)F-FDG-PET-MRI plus DWI may not increase nodal detection and N-staging performance in patients with oral malignancies compared to US and (18)F-FDG-PET/CT. CLINICAL RELEVANCE: Surgical staging of cervical lymph nodes will not be replaced even by advanced imaging modalities in the near future.

Radiation exposure of the radiologist's eye lens during CT-guided interventions.

BACKGROUND: In the past decade the number of computed tomography (CT)-guided procedures performed by interventional radiologists have increased, leading to a significantly higher radiation exposure of the interventionalist's eye lens. Because of growing concern that there is a stochastic effect for the development of lens opacification, eye lens dose reduction for operators and patients should be of maximal interest. PURPOSE: To determine the interventionalist's equivalent eye lens dose during CT-guided interventions and to relate the results to the maximum of the recommended equivalent dose limit. MATERIAL AND METHODS: During 89 CT-guided interventions (e.g. biopsies, drainage procedures, etc.) measurements of eye lens' radiation doses were obtained from a dedicated dosimeter system for scattered radiation. The sensor of the personal dosimeter system was clipped onto the side of the lead glasses which was located nearest to the CT gantry. After the procedure, radiation dose (µSv), dose rate (µSv/min) and the total exposure time (s) were recorded. RESULTS: For all 89 interventions, the median total exposure lens dose was 3.3 µSv (range, 0.03-218.9 µSv) for a median exposure time of 26.2 s (range, 1.1-94.0 s). The median dose rate was 13.9 µSv/min (range, 1.1-335.5 µSv/min). CONCLUSION: Estimating 50-200 CT-guided interventions per year performed by one interventionalist, the median dose of the eye lens of the interventional radiologist does not exceed the maximum of the ICRP-recommended equivalent eye lens dose limit of 20 mSv per year.

Functional evaluation of transplanted kidneys using arterial spin labeling MRI.

PURPOSE: To investigate non-contrast-enhanced arterial spin labeling (ASL) MRI for functional assessment of transplanted kidneys at 1.5 Tesla (T) and 3T. MATERIALS AND METHODS: This study was approved by the local ethics committee, and written informed consent was obtained from all participants. Ninety eight renal allograft recipients (mean age, 51.5 ± 14.6 years) were prospectively included in this study. ASL MRI was performed at 1.5T (n = 65) and 3T (n = 33) using a single-slice flow-sensitive alternating inversion recovery true-fast imaging with steady-state precession (FAIR True-FISP) sequence in the paracoronal plane. ASL perfusion was regional analyzed for the renal cortex on parameter maps. ASL was compared between patients with good or moderate allograft function (Group a; estimated glomerular filtration rate [eGFR] > 30 mL/min/1.73 m(2)) and patients with heavily impaired allograft function (Group b; eGFR ≤ 30 mL/min/1.73 m(2)) and correlated to renal function as determined by eGFR. RESULTS: ASL perfusion and eGFR were comparable at 1.5T (246.9 ± 66.8 mL/100 g/min and 41.9 ± 22.7 mL/min/1.73 m(2)) and 3T (236.5 ± 102.3 mL/100 g/min and 35.9 ± 22.9 mL/min/1.73 m(2)). ASL perfusion was significantly higher in group a (282.7 ± 60.8 mL/100 g/min) as compared to group b (178.2 ± 63.3 mL/100 g/min) (P < 0.0001). ASL perfusion values exhibited a significant correlation with renal function as determined by eGFR (r = 0.59; P < 0.0001). CONCLUSION: Cortical ASL perfusion values differ between patients with good or moderate allograft function and poor allograft function and correlate significantly with allograft function. Our results highlight the potential of ASL MRI for functional evaluation of renal allografts.

Hybrid [¹8F]-FDG PET/MRI including non-Gaussian diffusion-weighted imaging (DWI): preliminary results in non-small cell lung cancer (NSCLC).

PURPOSE: To assess the feasibility of non-Gaussian DWI as part of a FDG-PET/MRI protocol in patients with histologically proven non-small cell lung cancer. MATERIAL AND METHODS: 15 consecutive patients with histologically proven NSCLC (mean age 61 ± 11 years) were included in this study and underwent whole-body FDG-PET/MRI following whole-body FDG-PET/CT. As part of the whole-body FDG-PET/MRI protocol, an EPI-sequence with 5 b-values (0, 100, 500, 1000 and 2000 s/mm(2)) was acquired for DWI of the thorax during free-breathing. Volume of interest (VOI) measurements were performed to determine the maximum and mean standardized uptake value (SUV(max); SUV(mean)). A region of interest (ROI) was manually drawn around the tumor on b=0 images and then transferred to the corresponding parameter maps to assess ADC(mono), D(app) and K(app). To assess the goodness of the mathematical fit R(2) was calculated for monoexponential and non-Gaussian analysis. Spearman's correlation coefficients were calculated to compare SUV values and diffusion coefficients. A Student's t-test was performed to compare the monoexponential and non-Gaussian diffusion fitting (R(2)). RESULTS: T staging was equal between FDG-PET/CT and FDG-PET/MRI in 12 of 15 patients. For NSCLC, mean ADC(mono) was 2.11 ± 1.24 × 10(-3) mm(2)/s, Dapp was 2.46 ± 1.29 × 10(-3) mm(2)/s and mean Kapp was 0.70 ± 0.21. The non-Gaussian diffusion analysis (R(2)=0.98) provided a significantly better mathematical fitting to the DWI signal decay than the monoexponetial analysis (R(2)=0.96) (p<0.001). SUV(max) and SUV(mean) of NSCLC was 13.5 ± 7.6 and 7.9 ± 4.3 for FDG-PET/MRI. ADC(mono) as well as Dapp exhibited a significant inverse correlation with the SUV(max) (ADC(mono): R=-0.67; p<0.01; Dapp: R=-0.69; p<0.01) as well as with SUV(mean) assessed by FDG-PET/MRI (ADC(mono): R=-0.66; p<0.01; Dapp: R=-0.69; p<0.01). Furthermore, Kapp exhibited a significant correlation with SUV(max) (R=0.72; p<0.05) and SUV(mean) as assessed by FDG-PET/MRI (R=0.71; p<0.005). CONCLUSION: Simultaneous PET and non-Gaussian diffusion acquisitions are feasible. Non-Gaussian diffusion parameters show a good correlation with SUV and might provide additional information beyond monoexponential ADC, especially as non-Gaussian diffusion exhibits better mathematical fitting to the decay of the diffusion signal than monoexponential DWI.

Simultaneous 18F choline positron emission tomography/magnetic resonance imaging of the prostate: initial results.

PURPOSE: The purposes of this study were to evaluate the feasibility of simultaneous 18F choline positron emission tomography (PET) and magnetic resonance imaging (MRI) of the prostate and to present the first clinical results of the method. MATERIALS AND METHODS: From March 2012 to October 2012, a total of 15 consecutive patients were examined with simultaneous 18F choline PET/MRI. At the time of the examination, 8 patients had histologically proven prostate cancer, 2 patients had repeated prostate biopsies with negative results, and 5 patients had suspected prostate cancer with an elevated or rising prostate specific antigene level but did not have a prostate biopsy. Sequence protocol comprised T2-weighted high-resolution images and diffusion-weighted images of the prostate in addition to PET imaging. Image quality was assessed by 2 radiologists, and the PET images were evaluated qualitatively and quantitatively. RESULTS: Simultaneous PET/MRI of the prostate was accomplished successfully in all patients. The method proved to be robust without technical failure, and the image quality was rated to be diagnostic in all examinations except in 1 diffusion-weighted imaging (DWI) data set that was judged to be nondiagnostic because of susceptibility artifacts. High-resolution T2-weighted images allowed exact correlation of elevated focal or diffuse choline uptake to suspicious T2-weighted lesions of the prostate. A high accordance was found between PET and DWI. However, PET-positive lesions were found in 3 patients wherein DWI did not indicate tumor in suspicious T2-weighted lesions. CONCLUSIONS: Simultaneous positron emission tomography/magnetic resonance imaging of the prostate has the advantage of combining high-resolution prostate images, functional studies, and metabolic/molecular imaging. The PET component adds diagnostic confidence to the MRI-based parameters in identifying and localizing tumor in the prostate.

Standardized uptake values for [¹8F] FDG in normal organ tissues: comparison of whole-body PET/CT and PET/MRI.

PURPOSE: To compare maximum and mean standardized uptake values (SUVmax/mean) of normal organ tissues derived from [(18)F]-fluoro-desoxyglucose (FDG) positron emission tomography/magnetic resonance imaging (PET/MRI) using MR attenuation correction (MRAC) (DIXON-based 4-segment µ-map) with [(18)F]-FDG positron emission tomography/computed tomography (PET/CT) using CT-based attenuation correction (CTAC). METHODS AND MATERIALS: In 25 oncologic patients (15 men, 10 women; age 57 ± 13 years) after routine whole-body FDG-PET/CT (60 min after injection of 290 ± 40 MBq [(18)F]-FDG) a whole-body PET/MRI was performed (Magnetom Biograph mMR, Siemens Healthcare, Erlangen, Germany). Volumes of interest of 1.0 cm(3) were drawn in 7 physiological organ sites in MRAC-PET and the corresponding CTAC-PET images manually. Spearman correlation coefficients were calculated to compare MRAC- and CTAC based SUV values; Wilcoxon-Matched-Pairs signed ranks test was performed to test for potential differences. RESULTS: The mean delay between FDG-PET/CT and PET/MRI was 92 ± 18 min. Excellent correlations of SUV values were found for the heart muscle (SUVmax/mean: R=0.97/0.97); reasonably good correlations were found for the liver (R=0.65/0.72), bone marrow (R=0.42/0.41) and the SUVmax of the psoas muscle (R=0.41). For subcutaneous fat, the correlation coefficient was 0.66 for SUVmean (p<0.05). Correlations between MRAC and CTAC were non-significant for SUVmean of the psoas muscle, SUVmax of subcutaneous fat, SUVmax and SUVmean of the lungs, SUVmax and SUVmean of the blood-pool. The median SUVmax and SUVmean in MRAC-PET were lower than the respective CTAC values in all organs (p<0.05) but heart (SUVmax) and the bone marrow (SUVmean). CONCLUSION: In conclusion, in oncologic patients examined with PET/CT and PET/MRI SUVmax and SUVmean values generally correlate well in normal organ tissues, except the lung, subcutaneous fat and the blood pool. SUVmax and SUVmean derived from PET/MRI can be used reliably in clinical routine.

Diffusion-weighted imaging as part of hybrid PET/MRI protocols for whole-body cancer staging: does it benefit lesion detection?

PURPOSE: Positron emission tomography/magnetic resonance imaging (PET/MRI) requires efficient scan protocols for whole-body cancer staging. The aim of this study was to evaluate if the application of diffusion-weighted MR imaging (DWI) results in a diagnostic benefit for lesion detection in oncologic patients if added to a whole-body [18F]-fluorodesoxyglucose ([18F]-FDG) PET/MRI protocol. METHODS: 25 consecutive oncologic patients (16 men, 9 women; age 57 ± 12 years) prospectively underwent whole-body [18F]-FDG-PET/MRI including DWI on a hybrid PET/MRI scanner. A team of two readers assessed [18F]-FDG PET/MRI without DWI for primary tumors and metastases. In a second session, now considering DWI, readers reassessed [18F]-FDG PET/MRI accordingly. Additionally, the lesion-to-background contrast on [18F]-FDG PET and DWI was rated qualitatively (0, invisible; 1, low; 2, intermediate; 3, high). Wilcoxon's signed-rank test was performed to test for differences in the lesion-to-background contrast. RESULTS: 49 lesions were detected in 16 patients (5 primaries, 44 metastases). All 49 lesions were concordantly detected by [18F]-FDG PET/MRI alone and [18F]-FDG PET/MRI with DWI. The lesion-to-background contrast on DWI compared to [18F]-FDG PET was rated lower in 22 (44.9%) of 49 detected lesions resulting in a significantly higher lesion-to-background contrast on [18F]-FDG PET compared to DWI (P=0.001). CONCLUSIONS: DWI as part of whole-body [18F]-FDG PET/MRI does not benefit lesion detection. Given the necessity to optimize imaging protocols with regard to patient comfort and efficacy, DWI has to be questioned as a standard tool for whole-body staging in oncologic PET/MRI.

Does positron emission tomography data acquisition impact simultaneous diffusion-weighted imaging in a whole-body PET/MRI system?

OBJECTIVES: The purpose of this study was to test whether the acquisition of positron emission tomography (PET) does interfere with simultaneous diffusion weighted imaging (DWI) in an integrated whole-body PET/MRI system. MATERIAL AND METHODS: Fourteen consecutive oncological patients (9 men, 5 women; age 54 ± 13 years ([mean ± standard deviation]) scheduled for routine [(18)F]-FDG PET/CT were prospectively enrolled. For DWI, an echo planar imaging (EPI) sequence (b=0-500-1000 s/mm(2)) was acquired twice on an integrated whole-body 3T PET/MRI system in each patient; first with simultaneous PET acquisition and a second time with the PET component switched off. The apparent diffusion coefficient (ADC) and the signal-to-noise ratio at b=1000 s/mm(2) (SNR) of the myocardium, paraspinal muscle, liver, spleen, renal cortex and tumor tissue (if present) were measured. In addition, the coefficient of variation (CV) of ADC values was calculated. Student's t-test for paired samples was performed to test for differences of the mean ADC, ADC CV and SNR between DWI with and without simultaneous PET acquisition. RESULTS: There were no significant differences of the ADC [(mean ± standard deviation)] between the DWI acquisitions with and without simultaneous PET acquisition for the myocardium (2572 ± 441 × 10(-6)mm(2)/s and 2586 ± 376 × 10(-6)mm(2)/s, respectively) (P=0.817), paraspinal muscle (1279 ± 254 × 10(-6)mm(2)/s vs. 1219 ± 181 × 10(-6)mm(2)/s) (P=0.318), liver (1245 ± 158 × 10(-6)mm(2)/s vs. 1254 ± 171 × 10(-6)mm(2)/s) (P=0.848), spleen (980 ± 122 × 10(-6)mm(2)/s vs. 1000 ± 187 × 10(-6)mm(2)/s) (P=0.676) and renal cortex (1951 ± 226 × 10(-6)mm(2)/s vs. 1930 ± 273 × 10(-6)mm(2)/s) (P=0.730). Mean ADC of lymph node metastases (n=6) did not differ between with PET acquisition (853 ± 174 × 10(-6)mm(2)/s) and without simultaneous PET (865 ± 170 × 10(-6)mm(2)/s) (P=0.675). There were no significant differences between the CV of ADC values or the SNR values measured in DWI datasets that were acquired with or without simultaneous PET for any evaluated organ site. CONCLUSION: The simultaneous acquisition of DWI and PET on an integrated PET/MRI system does not impact ADC quantification of normal and tumor tissue and does not alter SNR. This knowledge provides a basis for the use of simultaneous multiparametric PET/MRI comprising DWI in diagnostic imaging and quantitative tumor therapy monitoring using repeated ADC measurements.

Correlation of biexponential diffusion parameters with arterial spin-labeling perfusion MRI: results in transplanted kidneys.

PURPOSE: The purpose of the present study was to explore the correlation between diffusion parameters assessed by biexponential analysis and the tissue perfusion measured by arterial spin labeling (ASL) imaging in renal allografts. MATERIAL AND METHODS: Seventeen recipients of renal allograft (11 men and 6 women; mean [SD] age, 53.6 [14.1] years) were included in this study. For diffusion-weighted imaging, a paracoronal echo-planar imaging sequence was acquired with 16 b values (range, b = 0-750 s/mm²) and 6 averages at 1.5 T. For the quantitative assessment of transplanted kidney perfusion, a flow-sensitive alternating inversion recovery true fast imaging with steady precession-ASL technique was applied. No respiratory gating was used. For quantitative analysis, region of interest measurements were performed on parameter maps. The Spearman correlation coefficients were calculated to determine the association between mean serum creatinine levels, estimated glomerular filtration rate, the apparent diffusion coefficient (ADC) of pure diffusion, the ADC of pseudodiffusion, the monoexponential ADC, the fraction of pseudodiffusion, and the tissue perfusion ASL values. RESULTS: In the renal cortex, the fraction of pseudodiffusion was 17.4% ± 4.0%, the apparent diffusion coefficient of pure diffusion was 160.7 ± 15.0 × 10⁻5 mm²/s, the monoexponential ADC was 193.2 ± 16.7 × 10⁻5 mm²/s, and the ADC of pseudodiffusion was 1421.0 ± 237.7 × 10⁻5 mm²/s. Mean cortical perfusion of renal allografts, as assessed with ASL imaging, was 247.2 ± 75.0 mL/100 g/min. There was a significant correlation between ASL perfusion and the fraction of pseudodiffusion (r = 0.68; P < 0.005) but not with the other diffusion coefficients. Both ASL perfusion and the fraction of pseudodiffusion exhibited a significant correlation with serum creatinine levels (r = 0.51 and r= 0.53, respectively; P < 0.05) and estimated glomerular filtration rate (r = 0.63 and r = 0.54, respectively; P < 0.05). CONCLUSIONS: This is the first study that shows a significant correlation between renal allograft perfusion, as assessed with ASL perfusion measurements, and the fraction of pseudodiffusion derived from biexponential diffusion-weighted imaging measurements.

Comparison of the diagnostic value of FDG-PET/CT and axillary ultrasound for the detection of lymph node metastases in breast cancer patients.

BACKGROUND: FDG-PET/CT is increasingly being used for breast cancer staging. Its diagnostic accuracy in comparison to ultrasound as the standard non-invasive imaging modality for the evaluation of axillary lymph nodes has yet not been evaluated. PURPOSE: To retrospectively compare the diagnostic value of full-dose, intravenously contrast-enhanced FDG-PET/CT and ultrasound for the detection of lymph node metastases in breast cancer patients. MATERIAL AND METHODS: Ninety patients (one patient with a bilateral carcinoma) (89 women, one man; mean age, 55.5 +/- 16.6 years) suffering from primary breast cancer underwent whole-body FDG-PET/CT and axillary ultrasound. The ipsilateral axillary fossa (n = 91) was evaluated for metastatic spread. The sensitivity, specificity, the positive predictive value (PPV), negative predictive value (NPV), and accuracy of both methods were calculated. The sensitivity and accuracy were statistically compared using the McNemar Test (P <0.05). Analyses were made on a patient basis. The number of patients with extra-axillary locoregional lymph node metastases exclusively detected by FDG-PET/CT was evaluated. For axillary lymph node metastases histopathology served as the reference standard. RESULTS: The sensitivity, specificity, PPV, NPV, and accuracy of FDG-PET/CT for the detection of axillary lymph node metastases were 54%, 89%, 77%, 74%, and 75%, respectively. For ultrasound it was 38%, 78%, 54%, 65%, and 62%, respectively. FDG-PET/CT was significantly more accurate than ultrasound for the detection of axillary lymph node metastases (P = 0.019). There was no statistically significant difference between the sensitivity of both modalities (P = 0.0578). FDG-PET/CT detected extra-axillary locoregional lymph node metastases in seven patients (8%) that had not been detected by another imaging modality. CONCLUSION: Though more accurate compared to ultrasound for evaluating the axillary lymph node status FDG-PET/CT is only as sensitive as ultrasound when it comes to the detection of axillary lymph node metastases. Due to the low sensitivity FDG-PET/CT cannot act as a substitute for Sentinel lymph node biopsy. FDG-PET/CT is able to detect previously unknown locoregional extra-axillary lymph node metastases.

Oncologic PET/MRI, part 2: bone tumors, soft-tissue tumors, melanoma, and lymphoma.

With integrated whole-body PET/MRI, a novel metabolic-anatomic imaging technique recently has been introduced into clinical practice. This review addresses PET/MRI of bone tumors, soft-tissue sarcoma, melanoma, and lymphoma. If PET/MRI literature is not yet available for some types of tumors, potential indications are based on available PET/CT and MRI data. PET/MRI seems to be of benefit in T-staging of primary bone tumors and soft-tissue sarcomas. With regard to N-staging, PET/MRI can be considered similarly accurate to PET/CT when applied as a whole-body staging approach. M-staging will benefit from MRI accuracy in the brain, the liver, and bone.

FDG-PET/CT for the early prediction of histopathological complete response to neoadjuvant chemotherapy in breast cancer patients: initial results.

BACKGROUND: Up to about one-quarter of patients treated with neoadjuvant chemotherapy do not adequately respond to the given treatment. By a differentiation between responders and non-responders ineffective toxic therapies can be prevented. PURPOSE: To retrospectively test if FDG-PET/CT is able to early differentiate between breast cancer lesions with pathological complete response (pCR) and lesions without pathological complete response (npCR) after two cycles of neoadjuvant chemotherapy (NACT). MATERIAL AND METHODS: In this retrospective study 26 breast cancer patients (mean age, 46.9 years ± 9.9 years) underwent a pre-therapeutic FDG-PET/CT scan and a subsequent FDG-PET/CT after the second cycle of NACT. Histopathology of resected specimen served as the reference standard. Maximum standardized uptake values (SUVmax) of cancer lesions before and after the second cycle of NACT were measured. Two evaluation algorithms were used: (a) pCR: Sinn Score 3 and 4, npCR: Sinn Score 0-2; (b) pCR: Sinn Score 4, npCR: Sinn Score 0-3. The absolute and relative decline of the SUVmax (ΔSUVmax, ΔSUVmax(%))was calculated. Differences of the SUVmax as well as of the SUVmax decline between pCR lesions and npCR lesions were tested for statistical significance P < 0.05. To identify the optimal cut-off value of ΔSUVmax(%) to differentiate between pCR lesions and npCR lesions a receiver-operating curve (ROC) analysis was performed. RESULTS: Using evaluation algorithm A the ΔSUVmax was 13.5 (pCR group) and 3.9 (npCR group) (P = 0.006); the ΔSUVmax(%) was 79% and 47%, respectively (P = 0.001). On ROC analysis an optimal cut-off ΔSUVmax(%) of 66% was found. Using evaluation algorithm B the ΔSUVmax was 17.5 (pCR group) and 4.9 (npCR group) (P = 0.013); the ΔSUVmax(%) was 89% and 51%, respectively (P = 0.003). On ROC analysis an optimal cut-off ΔSUVmax(%) of 88% was found. CONCLUSION: FDG-PET/CT may be able to early differentiate between pCR and npCR of primary breast cancer lesions after two cycles of NACT.

Virtual 3-D ¹8F-FDG PET/CT panendoscopy for assessment of the upper airways of head and neck cancer patients: a feasibility study.

PURPOSE: The aim of this study was to evaluate whether a virtual 3-D (18)F-fluorodeoxyglucose (FDG) positron emission tomography (PET)/CT panendoscopy is feasible and can be used for noninvasive imaging of the upper airways and pharyngeal/laryngeal tumours. METHODS: From (18)F-FDG PET/CT data sets of 40 patients (29 men, 11 women; age 61 ± 9 years) with pharyngeal or laryngeal malignancies virtual 3-D (18)F-FDG PET/CT panendoscopies were reconstructed and the image processing time was measured. The feasibility of assessing the oral cavity, nasopharynx, tongue base, soft palate, pharyngeal tonsils, epiglottis, aryepiglottic folds, piriform sinus, postcricoid space, glottis, subglottis, trachea, bronchi and oesophagus and of detecting primary tumours was tested. Results of fibre-optic bronchoscopy and histology served as the reference standard. RESULTS: The nasopharynx, tongue base, soft palate, pharyngeal tonsils, epiglottis, subglottis and the tracheobronchial tree were accessible in all 40, and the aryepiglottic folds, posterior hypopharyngeal wall, postcricoid space, piriform sinus, glottis, oral cavity and oesophagus in 37, 37, 37, 37, 33, 16 and 0 patients, respectively. In all 12 patients with restricted fibre-optic evaluation due to being primarily intubated, the subglottis was accessible via virtual panendoscopy. The primary tumour was depicted in 36 of 40 patients (90 %). The mean processing time for virtual (18)F-FDG PET/CT panendoscopies was 145 ± 98 s. CONCLUSION: Virtual (18)F-FDG PET/CT panendoscopy of the upper airways is technically feasible and can detect pharyngeal and laryngeal malignancies. This new tool can aid in the complete evaluation of the subglottic space in intubated patients and may be used for planning optical panendoscopies, biopsies and surgery in the future.

Virtual 18F-FDG PET/CT bronchoscopy for lymph node staging in non-small-cell lung cancer patients: present and future applications.

Virtual (18)F-fluorodeoxyglucose (FDG) PET/computed tomography (CT) bronchoscopies provide virtually realistic, 3D endoscopic views of the airways combining anatomical and functional data at a high resolution. Today, even very small airways can be imaged by virtual bronchoscopy. (18)F-FDG PET/CT bronchoscopy images are generated from standard whole-body (18)F-FDG PET/CT scan source data without any additional radiation exposure. The purpose of this review was to give an overview over the studies that are currently available, to provide the technical background of (18)F-FDG PET/CT bronchoscopy and to explain the diagnostic accuracy of (18)F-FDG PET/CT bronchoscopy. Moreover, this manuscript highlights potential future applications of this promising new imaging technique.

Oncologic PET/MRI, part 1: tumors of the brain, head and neck, chest, abdomen, and pelvis.

In oncology, staging forms the basis for prognostic consideration and directly influences patient care by determining the therapeutic approach. Cross-sectional imaging techniques, especially when combined with PET information, play an important role in cancer staging. With the recent introduction of integrated whole-body PET/MRI into clinical practice, a novel metabolic-anatomic imaging technique is now available. PET/MRI seems to be highly accurate in T-staging of tumor entities for which MRI has traditionally been favored, such as squamous cell carcinomas of the head and neck. By adding functional MRI to PET, PET/MRI may further improve diagnostic accuracy in the differentiation of scar tissue from recurrence of tumors such as rectal cancer. This hypothesis will have to be assessed in future studies. With regard to N-staging, PET/MRI does not seem to provide a considerable benefit as compared with PET/CT but provides similar N-staging accuracy when applied as a whole-body staging approach. M-staging will benefit from MRI accuracy in the brain and the liver. The purpose of this review is to summarize the available first experiences with PET/MRI and to outline the potential value of PET/MRI in oncologic applications for which data on PET/MRI are still lacking.

Diagnostic accuracy of dual-time-point 18F-FDG PET/CT for the detection of axillary lymph node metastases in breast cancer patients.

BACKGROUND: The diagnostic accuracy of FDG-PET/CT for the detection of axillary lymph node metastases in breast cancer patients acquired 60 min after FDG administration is reported to be only moderate, especially due to low sensitivity. PURPOSE: To test whether a delayed scan 90 min after FDG administration could enhance the diagnostic accuracy of FDG-PET/CT for the detection of axillary lymph node metastases. MATERIAL AND METHODS: Thirty-eight women suffering from primary breast cancer (mean age 52 years; range 25-78 years; standard deviation 14 years) underwent a pre-therapeutic dual-time-point FDG-PET/CT scan. The maximum standardized uptake value (SUVmax) of axillary lymph nodes was measured at two different time points (time point T1: 60 min after FDG injection, time point T2: 90 min after FDG injection). SUVmax of axillary lymph nodes at T1 and T2 were assessed for statistical significance using a paired Wilcoxon-Test (P < 0.05). At T1 a qualitative analysis of the FDG-PET/CT scan was performed to define physiologic and metastatic lymph nodes. At T2 an increase of the SUVmax of at least 3.75% over time was rated as indicating malignancy. The sensitivity, specificity, positive predictive value (PPV), negative predictive value (NPV), and the accuracy of FDG-PET/CT for the detection of axillary lymph node metastases was calculated at time points T1 and T2. Statistically significant differences were determined using Fisher's exact test (P < 0.05). Histopathology served as the standard of reference. A compartment based analysis was done. RESULTS: Axillary lymph nodes had a mean SUVmax of 1.6 (range 0.6-10.8; SD 1.9) at T1 and a mean SUVmax of 1.8 (range 0.5-17.9; SD 3.5) at T2. This difference was statistically significant (P = 0.047). The sensitivity, specificity, PPV, NPV, and accuracy of FDG-PET/CT for the detection of axillary lymph node metastases was 81%, 100%, 100%, 88%, and 92% at T1, and 88%, 50%, 56%, 85%, and 66% at T2, respectively. This difference was not statistically significant (P = 0.27). CONCLUSION: There is a slight increase of the FDG accumulation of axillary lymph nodes between 60 and 90 min after FDG administration. This increase did not translate into a statistical significant enhancement of the diagnostic accuracy of FDG-PET/CT for the detection of axillary lymph nodes. Especially due to false-positive results a delayed FDG-PET/CT scan 90 min after FDG administration is not able to enhance the diagnostic accuracy for the detection of lymph node metastases.

Selective and sequential transarterial chemoembolization: survival in patients with hepatocellular carcinoma.

PURPOSE: To assess the survival time of patients with HCC following transarterial chemoembolization performed in a highly selective and sequential way. PATIENTS AND METHODS: 124 HCC patients (102 male, 22 female; mean age 63±11 years) treated with selective and sequential chemoembolization at a single center were included. Selective chemoembolization was performed through a coaxially introduced microcatheter in a segmental or subsegmental hepatic artery. Treatment was stopped after complete stasis of the blood flow in the tumor-feeding vessel. The primary endpoint of the study was overall survival. RESULTS: The median overall survival of the entire patient population was 27.2 months (mo) (±8.9 mo, 95% CI 9.8 mo, 44.6 mo). When stratified according to liver function the median survival was 46.1 mo (±9.0 mo; 95% CI 28.5 mo, 63.7 mo) for Child-Pugh A and 11.1 mo (±4.3 mo; 95% CI 2.7 mo, 19.5 mo) for Child-Pugh B (p<.001). The median survival was 46.1 mo (±16.6 mo; 95% CI 13.5 mo, 78.7 mo) for BCLC stage A, 19.7 mo (±2.6 mo; 95% CI 14.6 mo, 24.8 mo) for BCLC stage B, and 14.4 mo (±5.0 mo; 95% CI 4.5 mo, 24.3 mo) for BCLC stage C (p<.01). CONCLUSION: Selective and sequential chemoembolization offers long survival times in patients with HCC. Those patients with preserved liver function benefit more than patients with limited liver reserve.