Search

Objectives: To present software for automated adipose tissue quantification of abdominal magnetic resonance imaging (MRI) data using fully convolutional networks (FCN) and to evaluate its overall performance-accuracy, reliability, processing effort, and time-in comparison with an interactive reference method., Materials and Methods: Single-center data of patients with obesity were analyzed retrospectively with institutional review board approval. Ground truth for subcutaneous (SAT) and visceral adipose tissue (VAT) segmentation was provided by semiautomated region-of-interest (ROI) histogram thresholding of 331 full abdominal image series. Automated analyses were implemented using UNet-based FCN architectures and data augmentation techniques. Cross-validation was performed on hold-out data using standard similarity and error measures., Results: The FCN models reached Dice coefficients of up to 0.954 for SAT and 0.889 for VAT segmentation during cross-validation. Volumetric SAT (VAT) assessment resulted in a Pearson correlation coefficient of 0.999 (0.997), relative bias of 0.7% (0.8%), and standard deviation of 1.2% (3.1%). Intraclass correlation (coefficient of variation) within the same cohort was 0.999 (1.4%) for SAT and 0.996 (3.1%) for VAT., Conclusion: The presented methods for automated adipose-tissue quantification showed substantial improvements over common semiautomated approaches (no reader dependence, less effort) and thus provide a promising option for adipose tissue quantification., Clinical Relevance Statement: Deep learning techniques will likely enable image-based body composition analyses on a routine basis. The presented fully convolutional network models are well suited for full abdominopelvic adipose tissue quantification in patients with obesity., Key Points: • This work compared the performance of different deep-learning approaches for adipose tissue quantification in patients with obesity. • Supervised deep learning-based methods using fully convolutional networks  were suited best. • Measures of accuracy were equal to or better than the operator-driven approach., (© 2023. The Author(s).)

Objectives: 4D flow MRI enables quantitative assessment of helical flow. We sought to generate normal values and elucidate changes of helical flow (duration, volume, length, velocities and rotational direction) and flow jet (displacement, flow angle) as well as wall shear stress (WSS)., Methods: We assessed the temporal helical existence (TH EX ), maximum helical volume (HV max ), accumulated helical volume (HV acc ), accumulated helical volume length (HVL acc ), maximum forward velocity (maxV for ), maximum circumferential velocity (maxV circ ), rotational direction (RD) and maximum wall shear stress (WSS) as reported elsewhere using the software tool Bloodline in 86 healthy volunteers (46 females, mean age 41 ± 13 years)., Results: WSS decreased by 42.1% and maxV for by 55.7% across age. There was no link between age and gender regarding the other parameters., Conclusion: This study provides age-dependent normal values regarding WSS and maxV for and age- and gender-independent normal values regarding TH EX , HV max , HV acc , HVL acc , RD and max V circ ., Key Points: • 4D flow provides numerous new parameters; therefore, normal values are mandatory. • Wall shear stress decreases over age. • Maximum helical forward velocity decreases over age., (© 2022. The Author(s).)

Purpose: To differentiate subtypes of hepatocellular adenoma (HCA) based on enhancement characteristics in gadoxetic acid (Gd-EOB) magnetic resonance imaging (MRI)., Materials and Methods: Forty-eight patients with 79 histopathologically proven HCAs who underwent Gd-EOB-enhanced MRI were enrolled (standard of reference: surgical resection). Two blinded radiologists performed quantitative measurements (lesion-to-liver enhancement) and evaluated qualitative imaging features. Inter-reader variability was tested. Advanced texture analysis was used to evaluate lesion heterogeneity three-dimensionally., Results: Overall, there were 19 (24%) hepatocyte nuclear factor (HNF)-1a-mutated (HHCAs), 37 (47%) inflammatory (IHCAs), 5 (6.5%) b-catenin-activated (bHCA), and 18 (22.5%) unclassified (UHCAs) adenomas. In the hepatobiliary phase (HBP), 49.5% (39/79) of all adenomas were rated as hypointense and 50.5% (40/79) as significantly enhancing (defined as > 25% intralesional GD-EOB uptake). 82.5% (33/40) of significantly enhancing adenomas were IHCAs, while only 4% (1/40) were in the HHCA subgroup (p < 0.001). When Gd-EOB uptake behavior was considered in conjunction with established MRI features (binary regression model), the area under the curve (AUC) increased from 0.785 to 0.953 for differentiation of IHCA (atoll sign + hyperintensity), from 0.859 to 0.903 for bHCA (scar + hyperintensity), and from 0.899 to 0.957 for HHCA (steatosis + hypointensity). Three-dimensional region of interest (3D ROI) analysis showed significantly increased voxel heterogeneity for IHCAs (p = 0.038)., Conclusion: Gd-EOB MRI is of added value for subtype differentiation of HCAs and reliably identifies the typical heterogeneous HBP uptake of IHCAs. Diagnostic accuracy can be improved significantly by the combined analysis of established morphologic MR appearances and intralesional Gd-EOB uptake., Key Points: •Gd-EOB-enhanced MRI is of added value for subtype differentiation of HCA. •IHCA and HHCA can be identified reliably based on their typical Gd-EOB uptake patterns, and accuracy increases significantly when additionally taking established MR appearances into account. •The small numbers of bHCAs and UHCAs remain the source of diagnostic uncertainty.

Objectives: Predicting post-hepatectomy liver failure (PHLF) after extended right hepatectomy following portal vein embolization (PVE) from serial gadoxetic acid-enhanced magnetic resonance imaging (MRI)., Methods: Thirty-six patients who underwent hepatectomy following PVE were evaluated prospectively with gadoxetic acid-enhanced MRI examinations at predefined intervals during the course of their treatment, i.e., before and 14 days and 28 days after PVE as well as 10 days after hepatectomy. Relative enhancement (RE) and volume of the left and right liver lobes were determined. The study population was divided into two groups with respect to signs of PHLF. Differences between the two groups were assessed using the Mann-Whitney U test, and predictive parameters for group membership were investigated using ROC and logistic regression analysis., Results: RE of the left lobe prior to PVE versus 14 days after PVE was significantly lower in patients with PHLF than in those without PHLF (Mann-Whitney U test p < 0.001) and proved to be the best predictor of PHLF in ROC analysis with an AUC of 0.854 (p < 0.001) and a cutoff value of - 0.044 with 75.0% sensitivity and 92.6% specificity. Consistent with this result, logistic linear regression analysis adjusted for age identified the same parameter to be a significant predictor of PHLF (p = 0.040)., Conclusions: Gadoxetic acid-enhanced MRI performed as an imaging-based liver function test before and after PVE can help to predict PHLF. The risk of PHLF can be predicted as early as 14 days after PVE., Key Points: • To predict the likelihood of post-hepatectomy liver failure, it is important to estimate not only future liver remnant volume prior to extended liver resection but also future liver remnant function. • Future liver remnant function can be predicted by performing gadoxetic acid-enhanced MRI as an imaging-based liver function test before and after portal vein embolization. • A reduction of relative enhancement of the liver in gadoxetic acid-enhanced MRI after portal vein embolization of 0.044 predicts post-hepatectomy liver failure with 75.0% sensitivity and 92.6% specificity.

Objectives: To evaluate changes in liver function after right portal vein embolization (PVE) and extended right hemihepatectomy using gadolinium ethoxybenzyl-DTPA-enhanced (Gd-EOB-DTPA) MRI., Methods: In this prospective trial, 37 patients undergoing PVE were examined before and 14 and 28 days after PVE and 10 days after extended hemihepatectomy using Gd-EOB-DTPA-enhanced MRI. Lobar volume, kinetic growth rate (KGR), relative enhancement (RE) as well as hepatocellular uptake index (HUI) and fat signal fraction (FSF) were calculated for each lobe., Results: RE of the left liver lobe (LLL) was steadily increasing after PVE and decreased to 0.48 ± 0.19 10 days after surgery, which is significantly lower than 14 days and 28 days post PVE (P < 0.05). KGR was 14.06 ± 9.82%/week for the period from PVE to 14 days after PVE. HUI of the LLL increased steadily after PVE and was significantly higher at both 14 and 28 days after PVE compared to pre PVE (P < 0.05). HUI of the residual liver after surgery was lower than before., Conclusions: Gd-EOB-DTPA-enhanced MRI may be used to monitor the functional increase in the FLR after PVE and to depict the intraoperative liver injury leading to a decrease in liver remnant function., Key Points: • The most significant FLR volume increase happens within the first 14 days. • No MRI parameter was able to predict the success of FLR growth. • Our data suggest an early resection about 14 days after PVE. • Routine Gd-EOB-DTPA-enhanced MRI might be suitable to replace ICG-test.

Objectives: Transarterial chemoembolization (TACE) is established as bridging therapy of HCC listed for transplantation (LT). CT-guided brachytherapy (CTB) has not been evaluated as a bridging concept. We compared CTB and TACE for bridging before LT in HCC patients., Methods: Twelve patients with HCC received LT after CTB (minimal tumour dose, 15-20 Gy). Patients were matched (CTB:TACE, 1:2) by sex, age, number and size of lesions, and underlying liver disease with patients who received TACE before transplantation. Study endpoints were extent of necrosis at histopathology and recurrence rate after OLT., Results: There were no significant differences between the CTB and TACE groups regarding Child-Pugh category (p = 0.732), AFP (0.765), time on waiting list (p = 0.659), number (p = 0.698) and size (p = 0.853) of HCC lesions, fulfilment of Milan-criteria (p = 0.638), or previous liver-specific treatments. CTB achieved higher tumour necrosis rates than TACE (p = 0.018). The 1- and 3-year recurrence rate in the CTB group was 10 and 10 % vs. TACE, 14 and 30 % (p = 0.292)., Conclusions: Our data show comparable or even better response and post-LT recurrence rates of CTB compared to TACE for treating HCC in patients prior to LT. CTB should be further evaluated as an alternative bridging modality, especially for patients not suited for TACE., Key Points: • CT-guided interstitial brachytherapy (CTB) is a promising alternative to transarterial chemoembolization (TACE). • CTB instead of TACE is possible for bridging to liver transplantation in HCC patients. • HCC recurrence was not associated with CTB despite potential tumour seeding.

Objectives: Evaluation of computed tomography (CT) and magnetic resonance imaging (MRI) for differentiation of pancreatic intraductal papillary mucinous neoplasm (IPMN) subtypes based on objective imaging criteria., Methods: Fifty-eight patients with 60 histologically confirmed IPMNs were included in this retrospective study. Eighty-three imaging studies (CT,n = 42; MRI,n = 41) were analysed by three independent blinded observers (O1-O3), using established imaging criteria to assess likelihood of malignancy (-5, very likely benign; 5, very likely malignant) and histological subtype (i.e., low-grade (LGD), moderate-grade (MGD), high-grade dysplasia (HGD), early invasive carcinoma (IPMC), solid carcinoma (CA) arising from IPMN)., Results: Forty-one benign (LGD IPMN,n = 20; MGD IPMN,n = 21) and 19 malignant (HGD IPMN,n = 3; IPMC,n = 6; solid CA,n = 10) IPMNs located in the main duct (n = 6), branch duct (n = 37), or both (n = 17) were evaluated. Overall accuracy of differentiation between benign and malignant IPMNs was 86/92 % (CT/MRI). Exclusion of overtly malignant cases (solid CA) resulted in overall accuracy of 83/90 % (CT/MRI). The presence of mural nodules and ductal lesion size ≥30 mm were significant indicators of malignancy (p = 0.02 and p < 0.001, respectively)., Conclusions: Invasive IPMN can be identified with high confidence and sensitivity using CT and MRI. The diagnostic problem that remains is the accurate radiological differentiation of premalignant and non-invasive subtypes., Key Points: • CT and MRI can differentiate benign from malignant forms of IPMN. • Identifying (pre)malignant histological IPMN subtypes by CT and MRI is difficult. • Overall, diagnostic performance with MRI was slightly (not significantly) superior to CT.

Objectives: To compare Gd-EOB-enhanced MRI and (99m)Tc-mebrofenin hepatobiliary scintigraphy (HBS) as imaging-based liver function tests for separate evaluation of right (RLL) and left liver lobe (LLL) function., Methods: Fourteen patients underwent Gd-EOB-enhanced MRI and (99m)Tc-mebrofenin HBS after portal vein embolization within 24 h. Relative enhancement (RE) and hepatic uptake index (HUI) were determined from MRI; and T max, T 1/2 and mebrofenin uptake were determined from HBS, all values separately for RLL and LLL., Results: Mebrofenin uptake correlated significantly with HUI and RE for both liver lobes. There was strong correlation of mebrofenin uptake with HUI for RLL (r (2) = 0.802, p = 0.001) and RE for LLL (r (2) = 0.704, p = 0.005) and moderate correlation with HUI for LLL (r (2) = 0.560, p = 0.037) and RE for RLL (r (2) = 0.620, p = 0.018). Correlating the percentage share of RLL function derived from MRI (with HUI) with the percentage of RLL function derived from mebrofenin uptake revealed a strong correlation (r (2) = 0.775, p = 0.002)., Conclusions: Both RE and HUI correlate with mebrofenin uptake in HBS. The results suggest that Gd-EOB-enhanced MRI and (99m)Tc-mebrofenin HBS may equally be used to separately determine right and left liver lobe function., Key Points: • Information about liver function can be acquired with routine Gd-EOB-MRI. • Gd-EOB-MRI and (99m) Tc-mebrofenin HBS show elevated function of non-embolized lobe. • Gd-EOB-MRI and (99m) Tc-mebrofenin HBS can determine lobar liver function.

Objectives: Evaluation of enhancement characteristics of histopathologically confirmed focal nodular hyperplasias (FNHs) and hepatocellular adenomas (HCAs) with gadoxetic acid-enhanced MRI., Methods: Sixty-eight patients with 115 histopathologically proven lesions (FNHs, n=44; HCAs, n=71) examined with gadoxetic acid-enhanced MRI were retrospectively enrolled (standard of reference: surgical resection, n=53 patients (lesions: FNHs, n=37; HCAs, n=53); biopsy, n=15 (lesions: FNHs, n=7; HCAs, n=18)). Two radiologists evaluated all MR images regarding morphological features as well as the vascular and hepatocyte-specific enhancement in consensus., Results: For the hepatobiliary phase, relative enhancement of the lesions and lesion to liver enhancement were significantly lower for HCAs (mean, 48.7 (±48.4)%and 49.4 (±33.9) %) compared to FNHs (159.3 (±92.5) %; and 151.7 (±79) %; accuracy of 89%and 90 %, respectively; P<0.001). Visual strong uptake of FNHs vs. hypointensity of HCAs in the hepatobiliary phase resulted in an accuracy of 92 %. This parameter was superior to all other morphological and dynamic vascular criteria alone and in combination (accuracy, 54–85 %)., Conclusions: For differentiation of FNHs and HCAs by means of MRI, gadoxetic acid uptake in the hepatobiliary phase was found to be superior to all other criteria alone and in combination., Key Points: EOB-MRI is well suited to differentiate FNHs and hepatocellular adenomas. For this purpose hepatobiliary phase is superior to unenhanced and dynamic imaging. Hepatobiliary phase (peripheral) hyper- or isointensity is typical for FNH. Hepatobiliary phase hypointensity is typical for hepatocellular adenomas. EOB-MRI helps to avoid misinterpretations of benign hepatocellular lesions.

Purpose: To retrospectively analyze the clinical outcome of patients with hepatic metastases from renal cell carcinoma who were treated with computed-tomography-guided high-dose-rate brachytherapy (CT-HDRBT)., Methods: Ten patients (7 men and 3 women; median age 72 ± 7.9 years) with a total number of 16 hepatic metastases from histologically proven renal cell carcinoma were treated with CT-HDRBT after discussing the case in an interdisciplinary tumor conference. All patients had underwent nephrectomy before CT-HDRBT. Three patients had extrahepatic manifestations (2 lung and 1 bone). Six patients had received immunotherapy or targeted therapy before CT-HDRBT. Follow-up included gadoxetic acid (Gd-EOB-DTPA) enhanced MRI two times within 6-8 weeks and after that every 3 months after treatment to evaluate treatment efficacy., Results: Mean follow-up time was 21.6 ± 13.7 months. One patient developed local and systemic (pulmonary and osseous) progression after 10.8 months which was treated with targeted therapy and died 20.3 months after CT-HDRBT. None of the remaining nine patients developed local progression or died during the follow-up period. Five patients developed systemic progression (3 pulmonary, 1 osseous and 1 locally at the site of nephrectomy) after an average of 19.7 ± 5.5 months., Conclusions: CT-HDRBT is a viable alternative to hepatic resection of liver metastases from renal cell carcinoma in selected patients.

Objectives: To prospectively evaluate the early development of regional liver function after right portal vein embolisation (PVE) with Gd-EOB-DTPA-enhanced MRI in patients scheduled for extended right hemihepatectomy., Methods: Ten patients who received a PVE before an extended hemihepatectomy were examined before and 14 days after PVE using Gd-EOB-DTPA-enhanced MRI of the liver. In these sequences representative region of interest measurements were performed in the embolised right (RLL) and the non-embolised left liver lobe (LLL). The volume as well as hepatic uptake index (HUI) was calculated independently for each lobe., Results: Relative enhancement 14 days after PVE decreased in the RLL and increased significantly in the LLL (P < 0.05). Average hepatic uptake index (HUI) for RLL was significantly lower 14 days after PVE than before PVE (P < 0.05) and significantly higher for LLL (P < 0.05)., Conclusions: A significant shift of contrast uptake from the right to the left liver lobe can be depicted as early as 14 days after right PVE by using Gd-EOB-DTPA-enhanced MRI, which could reflect the redirected portal venous blood flow and the rapid utilisation of a hepatic functional reserve., Key Points: • Preoperative portal vein embolisation (PVE) is widely performed before right-sided hepatic resection. • PVE increases intravenous contrast medium uptake in the left lobe of liver. • The hepatic uptake index for the left liver lobe increases rapidly after PVE. • Left liver lobe function increase may be visualised by Gd-EOB-DTPA-enhanced MRI.

Objective: The purpose of this study was to evaluate enhancement characteristics of hepatocellular adenomas (HCAs) using gadoxetic acid as a hepatocyte-specific MR contrast agent., Methods: Twenty-four patients with histopathologically proven HCAs were retrospectively identified. MRI consisted of T1- and T2-weighted (w) sequences with and without fat saturation (fs), multiphase dynamic T1-w images, and fs T1-w images during the hepatobiliary phase. Standard of reference was surgical resection (n = 19) or biopsy (n = 5). Images were analysed for morphology and contrast behaviour including signal intensity (SI) measurement on T1-w images normalised to the pre-contrast base line., Results: In total 34 HCAs were evaluated. All HCAs showed enhancement in the arterial phase; 38 % of HCAs showed reduced contrast enhancement ("wash-out") in the venous phase. All HCAs showed enhancement (SI increase, 56 ± 53 %; P <0.001) in the hepatobiliary phase, although liver uptake was stronger (96 ± 58 %). Thus, 31 of all HCAs (91 %) appeared hypointense to the surrounding liver in the hepatobiliary phase, while 3 out of 34 lesions were iso-/hyperintense., Conclusions: Gadoxetic acid accumulates in HCAs in the hepatobiliary phase, although significantly less than in surrounding liver. Thus, HCA appears in the vast majority of cases as a hypointense lesion on hepatobiliary phase images., Key Points: • Magnetic resonance-specific contrast agents are now available for hepatic imaging. • Hepatocellular adenomas enhance with gadoxetic acid as in previous CT/MRI experience. • Enhancement during the hepatobiliary phase is less in HCAs than in liver. • Typical HCAs appear as hypointense lesions on T1-w hepatobiliary phase images. • True hyperintense HCA enhancement can occasionally occur during the hepatobiliary phase.

Objectives: Evaluate the clinical outcome of CT-guided high-dose-rate-brachytherapy (CT-HDRBT) of hepatocellular carcinoma (HCC) larger than 5 cm in diameter with the goal of local tumour control (LTC)., Methods: Thirty-five patients with 35 unresectable HCCs ranging in size from 5 to 12 cm (mean: 7.1 cm) were treated with CT-HDRBT. Tumours were classified into two groups according to diameter: "large lesions" (5-7 cm) and "very large lesions" (>7 cm). Tumour response was evaluated by Gd-EOB-DTPA-enhanced liver magnetic resonance imaging (MRI) performed before, 6 weeks after, and then every 3 months after treatment. Endpoints included local tumour control (LTC), progression-free survival (PFS) and overall survival (OS)., Results: Nineteen tumours were classified as "large" and 16 as "very large". Complete tumour enclosure was achieved in all patients after the first CT-HDRBT session. Five patients were lost to follow-up. At a mean follow-up of 12.8 months, two patients had local progression (6.7%), one in each group. Nine patients (30%) experienced distant progression, five (26.3%) in the "large" and four (25%) in the "very large" group. No patients died during the follow-up period. No major complications were recorded., Conclusions: CT-HDRBT is a promising therapy for HCCs that exceed indications for thermal ablation., Key Points: • Computed Tomography guided high-dose-rate brachytherapy offers new therapeutic options for hepatocellular carcinoma • CT-HDRBT can be safely practised in HCCs exceeding 5 cm in diameter • CT-HDRBT offers high rate of local control where thermal ablation is impossible • CT-HDRBT could be a valid alternative to TACE for intermediate stage HCC.

Objective: The management of non-contrast-enhancing brain tumours largely depends on biopsy, which allows a differentiation of low-grade gliomas (LGG) from high-grade gliomas (HGG). The aim of this study was to compare positron emission tomography using 2-[(18)F]-fluoro-2-deoxy-D: -glucose (FDG-PET) and O-(2-[(18)F]-fluoroethyl)-L: -tyrosine (FET-PET) in terms of providing target regions for biopsies., Materials and Methods: Fifteen consecutive patients with newly diagnosed brain tumours (n = 11) or suspected recurrence of a known LGG (n = 4), in whom MRI demonstrated no contrast enhancement, were studied by both FET-PET and FDG-PET. FET-PET, FDG-PET and MRI data were fused, and then transferred to the neurosurgical navigation system, prior to neurosurgical interventions., Results: Histology showed HGG (WHO grade III) in 6/15 and LGG (WHO grade II) in 9/15 patients. FET-PET revealed an increased intratumoural tracer uptake in 8/9 LGG and in 5/6 HGG. FDG-PET depicted hypermetabolic spots in 2/9 LGG and in 4/6 HGG. In 6 patients we observed an increased intratumoural uptake of both tracers. In 4 of them, the area of highest FET accumulation in the tumour corresponded to the focus of increased FDG uptake., Conclusions: FET-PET appears to be superior to FDG-PET for biopsy planning in non-contrast-enhancing brain tumours. FDG-PET does not provide any additional information in this issue.

The purpose of this study was to evaluate the accuracy of MDCT for preoperative assessment of hepatic vascular anatomy and the identification of liver-transplantation (OLT) patients at risk of developing subsequent splenic artery steal syndrome (SASS). A total of 145 patients with liver cirrhosis who had undergone OLT and had pre-operative three-phase MDCT (4- to 64-rows) within 100 days before OLT were enrolled retrospectively. MDCT and 3Ds were reviewed by two independent blinded observers (O1/O2). Pre-operative imaging findings were correlated with intra-operative results; findings indicative for SASS were correlated with clinical data and DSA. Among all 145 patients, 16 patients (11%) showed accessory hepatic arteries (accuracy O1/O2, 97%; with 3Ds, 100%); 32 (22%) patients had replaced hepatic arteries (accuracy O1, 97%; O2, 95%; with 3Ds, 100%; kappa = 0.87 and 0.89, P < 0.001). Among 119 patients, 12 patients developed SASS after OLT. The logistic regression model revealed the spleen volume (P = 0.0105) as a predictive factor of SASS. With spleen volumes >or=829 ml, an accuracy of 75% for prediction of SASS was obtained. MDCT with three-dimensional post-processing (3Ds) was highly accurate for pre-operative hepatic vessel evaluation in patients before OLT. In addition, spleen volume was a predictive factor for developing SASS after OLT.

The purpose of the study was to establish a diagnostic approach to the preparation of patients with colorectal liver metastases considered for transarterial radioembolization (RE). Twenty-two patients sequentially underwent computed tomography (CT; thorax/abdomen), magnetic resonance imaging (MRI; liver; hepatocyte-specific contrast), positron emission tomography (PET/PET-CT; F18-fluoro-desoxy-glucose), and angiography with perfusion scintigraphy [planar imaging; tomography with integrated CT (SPECT-CT)]. The algorithm was continued when no contraindication or alternative treatment option was found. The impact of each test on the therapy decision and RE management was recorded. Patient evaluation using CT revealed contraindications for RE in 4/22 patients (18%). Of the remaining 18 patients, 2 were excluded and 3 were assigned to locally ablative treatment based on MRI and PET results (28%). The remaining 13 patients entered the planning algorithm: SPECT-CT revealed gastrointestinal tracer accumulations in 4 (31%) patients [SPECT, 2 (15%)], making a modified application necessary. In five patients (38%), planar scintigraphy revealed relevant hepatopulmonary shunting. Therapy was finally administered to all 13 patients without therapy-related pulmonary or gastrointestinal morbidity. Each part of the diagnostic algorithm showed a relevant impact on patient management. The sequential approach appears to be suitable and keeps the number of unnecessary treatments and therapy risks to a minimum.

The objective was the evaluation of minimum intensity projections (MinIP) of 16-channel multidetector computed tomography (MDCT) data for the visualization of biliary ducts with magnetic resonance cholangiopancreatography (MRCP) as reference method. Twenty-five patients with biliary obstruction who received MDCT of the abdomen and MRCP without subsequent interventions were analysed. Coronal and axial MinIP were reconstructed from the MDCT-data. The evaluation of image quality and the quantitative comparison to MRCP was performed by two observers in consensus. The additional diagnostic value of MinIP compared with conventionally visualised MDCT was assessed by three independent observers. With MRCP as the reference method, MinIP was superior to conventional MDCT concerning the visualization of the extent of bile duct dilatation (r, 1.000 vs 0.699) and the correlation of diameter measurement (r, 0.979 vs 0.942). Subsidiary to conventional MDCT, MinIP revealed an improvement of visualization of the biliary system in 73% of cases. Concerning the additional diagnostic value, MinIP allowed for a better definition of the obstruction site in 13% of patients, and in one patient a change of diagnosis was observed. Thus, MinIP can improve the diagnostic assessment of biliary obstructions in MDCT imaging.

The purpose of this study was to investigate the diagnostic accuracy of non-overlapping 10-mm axial and coronal maximum intensity projections (MIP) in comparison with standard axial 1-mm and 5-mm slices in the detection of pulmonary nodules. Sixty patients with suspected nodules who underwent multislice spiral CT of the chest were evaluated. Axial 1-mm and 5-mm slices as well as non-overlapping 10-mm axial/coronal MIPs were interpreted independently by three blinded radiologists. After initial review, a retrospective consensus session was performed for agreement on final nodule counts using the axial 1-mm slices as gold standard. Small nodules of less than 5 mm in size were most accurately detected by the axial MIPs. Receiver operating characteristic (ROC) analysis of these small nodules showed that 5-mm slices were not capable of a statistically significant differentiation of nodules from other focal lesions in two observers (p=0.034 and p=0.012, respectively) whereas 1-mm slices and coronal/axial MIPs did allow a statistically significant differentiation in all observers (p<0.001). Nodules larger than 5 mm were equally well depicted with all modalities. Non-overlapping 10-mm axial MIPs improve the accuracy in the detection of small pulmonary nodules.

The aim of the study was to assess the clinical value of combined SPECT/CT imaging using L: -3-[123I]iodine-alpha-methyl tyrosine (IMT) for the differential diagnosis of recurrences in patients pre-treated for head and neck cancer. Thirty-four consecutive patients with biopsy-proven carcinomas, who had previously been treated by surgery and/or radio/chemotherapy, were examined at our clinic by IMT-SPECT using a dual-head system with integrated low-dose CT. SPECT results were correlated with histopathology, clinical and CT/MRI follow-up data. In the follow-up after SPECT examination, the final diagnosis of recurrent tumour was established in 26 patients; the remaining eight patients were recurrence-free (follow-up >6 months). IMT-SPECT/CT correctly detected recurrent disease and/or neck lymph node metastases in 22 patients. In addition, distant metastases were displayed in two patients. The study was false-negative in four patients (sensitivity 85%). True-negative results were registered in seven patients, and false-positive in one patient. Image fusion with coregistered low-dose CT facilitates the localisation and interpretation of IMT-SPECT findings. IMT-SPECT using integrated low-dose CT is a promising non-invasive imaging tool for the detection of head and neck cancer recurrences and their differentiation from treatment-induced changes.

The aim of this paper is to examine signal-to-noise ratio (SNR), contrast-to-noise ratio (CNR) and image quality of cardiac CINE imaging at 1.5 T and 3.0 T. Twenty volunteers underwent cardiac magnetic resonance imaging (MRI) examinations using a 1.5-T and a 3.0-T scanner. Three different sets of breath-held, electrocardiogram-gated (ECG) CINE imaging techniques were employed, including: (1) unaccelerated SSFP (steady state free precession), (2) accelerated SSFP imaging and (3) gradient-echo-based myocardial tagging. Two-dimensional CINE SSFP at 3.0 T revealed an SNR improvement of 103% and a CNR increase of 19% as compared to the results obtained at 1.5 T. The SNR reduction in accelerated 2D CINE SSFP imaging was larger at 1.5 T (37%) compared to 3.0 T (26%). The mean SNR and CNR increase at 3.0 T obtained for the tagging sequence was 88% and 187%, respectively. At 3.0 T, the duration of the saturation bands persisted throughout the entire cardiac cycle. For comparison, the saturation bands were significantly diminished at 1.5 T during end-diastole. For 2D CINE SSFP imaging, no significant difference in the left ventricular volumetry and in the overall image quality was obtained. For myocardial tagging, image quality was significantly improved at 3.0 T. The SNR reduction in accelerated SSFP imaging was overcompensated by the increase in the baseline SNR at 3.0 T and did not result in any image quality degradation. For cardiac tagging techniques, 3.0 T was highly beneficial, which holds the promise to improve its diagnostic value.

The aim of this study was to compare CT, MRI and FDG-PET in the prediction of outcome of neoadjuvant radiochemotherapy in patients with locally advanced primary rectal cancer. A total of 23 patients with T3/4 rectal cancer underwent a preoperative radiochemotherapy combined with regional hyperthermia. Staging was performed using four-slice CT (n=23), 1.5-T MRI (n=10), and (18)F-FDG-PET (n=23) before and 2-4 weeks after completion of neoadjuvant treatment. Response criteria were a change in T category and tumour volume for CT and MRI and a change in glucose uptake (standard uptake value) within the tumour for FDG-PET. Imaging results were compared with those of pretherapy endorectal ultrasound and histopathological findings. Histopathology showed a response to neoadjuvant therapy in 13 patients whereas 10 patients were classified as nonresponders. The mean SUV reduction in responders (60+/-14%) was significantly higher than in nonresponders (37+/-31%; P=0.030). The sensitivity and specificity of FDG-PET in identifying response was 100% (CT 54%, MRI 71%) and 60% (CT 80%, MRT 67%). Positive and negative predictive values were 77% (CT 78%, MRI 83%) and 100% (CT 57%, MRI 50%) (PET P=0.002, CT P=0.197, MRI P=0.500). These results suggest that FDG-PET is superior to CT and MRI in predicting response to preoperative multimodal treatment of locally advanced primary rectal cancer.

The objective was the evaluation of single photon emission computed tomography (SPECT) with integrated low dose computed tomography (CT) in comparison with a retrospective fusion of SPECT and high-resolution CT and a side-by-side analysis for lesion localisation in patients with neuroendocrine tumours. Twenty-seven patients were examined by multidetector CT. Additionally, as part of somatostatin receptor scintigraphy (SRS), an integrated SPECT-CT was performed. SPECT and CT data were fused using software with a registration algorithm based on normalised mutual information. The reliability of the topographic assignment of lesions in SPECT-CT, retrospective fusion and side-by-side analysis was evaluated by two blinded readers. Two patients were not enrolled in the final analysis because of misregistrations in the retrospective fusion. Eighty-seven foci were included in the analysis. For the anatomical assignment of foci, SPECT-CT and retrospective fusion revealed overall accuracies of 91 and 94% (side-by-side analysis 86%). The correct identification of foci as lymph node manifestations (n=25) was more accurate by retrospective fusion (88%) than from SPECT-CT images (76%) or by side-by-side analysis (60%). Both modalities of image fusion appear to be well suited for the localisation of SRS foci and are superior to side-by-side analysis of non-fused images especially concerning lymph node manifestations.

This study compared different magnetic resonance imaging (MRI) methods with Tl(201) single photon emission computerized tomography (SPECT) and the "gold standard" for viability assessment, functional recovery after coronary artery bypass grafting (CABG). Twenty patients (64+/-7.3 years) with severely impaired left ventricular function (ejection fraction [EF] 28.6+/-8.7%) underwent MRI and SPECT before and 6 months after CABG. Wall-motion abnormalities were assessed by stress cine MRI using low-dose dobutamine. A segment with a nonreversible defect in Tl(201)-SPECT and a delayed enhancement (DE) in an area >50% of the entire segment, as well as an end-diastolic wall thickness <6 mm, was defined as nonviable. The mean postoperative EF (n=20) improved slightly from 28.6+/-8.7% to 32.2+/-12.4% (not significant). Using the Tl(201)-SPECT as the reference method, end-diastolic wall thickness, MRI-DE, and stress MRI showed high sensitivity of 94%, 93%, and 84%, respectively, but low specificities. Using the recovery of contractile function 6 months after CABG as the gold standard, MRI-DE showed an even higher sensitivity of 99%, end-diastolic wall thickness 96%, stress MRI 88%, and Tl(201)-SPECT 86%. MRI-DE showed advantages compared with the widely used Tl(201)-SPECT and all other MRI methods for predicting myocardial recovery after CABG.