Fully automated preoperative liver volumetry incorporating the anatomical location of the central hepatic vein

The precise preoperative calculation of functional liver volumes is essential prior major liver resections, as well as for the evaluation of a suitable donor for living donor liver transplantation. The aim of this study was to develop a fully automated, reproducible, and quantitative 3D volumetry of the liver from standard CT examinations of the abdomen as part of routine clinical imaging. Therefore, an in-house dataset of 100 venous phase CT examinations for training and 30 venous phase ex-house CT examinations with a slice thickness of 5 mm for testing and validating were fully annotated with right and left liver lobe. Multi-Resolution U-Net 3D neural networks were employed for segmenting these liver regions. The Sorensen-Dice coefficient was greater than 0.9726 +/- 0.0058, 0.9639 +/- 0.0088, and 0.9223 +/- 0.0187 and a mean volume difference of 32.12 +/- 19.40 ml, 22.68 +/- 21.67 ml, and 9.44 +/- 27.08 ml compared to the standard of reference (SoR) liver, right lobe, and left lobe annotation was achieved. Our results show that fully automated 3D volumetry of the liver on routine CT imaging can provide reproducible, quantitative, fast and accurate results without needing any examiner in the preoperative work-up for hepatobiliary surgery and especially for living donor liver transplantation.Projekt DEA

Prediction of left lobe hypertrophy after right lobe radioembolization of the liver using a clinical data model with external validation

In cirrhotic patients with hepatocellular carcinoma (HCC), right-sided radioembolization (RE) with Yttrium-90-loaded microspheres is an established palliative therapy and can be considered a “curative intention” treatment when aiming for sequential tumor resection. To become surgical candidate, hypertrophy of the left liver lobe to > 40% (future liver remnant, FLR) is mandatory, which can develop after RE. The amount of radiation-induced shrinkage of the right lobe and compensatory hypertrophy of the left lobe is difficult for clinicians to predict. This study aimed to utilize machine learning to predict left lobe liver hypertrophy in patients with HCC and cirrhosis scheduled for right lobe RE, with external validation. The results revealed that machine learning can accurately predict relative and absolute volume changes of the left liver lobe after right lobe RE. This prediction algorithm could help to estimate the chances of conversion from palliative RE to curative major hepatectomy following significant FLR hypertrophy

Measuring the density of iodine depositions: Detecting an invisible residual tumor after conventional transarterial chemoembolization.

PURPOSE:The purpose of this study is to evaluate the use of density measurements in the diagnosis of an underlying residual tumor beyond iodine depositions after Lipiodol-based conventional transarterial chemoembolization (cTACE). METHOD AND MATERIALS:Thirty follow-up CT scans of 20 patients 6-12 weeks after Lipiodol-based cTACE, receiving a digital subtraction angiography at the same time, were analyzed. Reference for the detection of a residual tumor was the angiography, and a visible contrast enhancement was categorized as a residual tumor (n = 16 with residual tumor; n = 14 without residual tumor). The density of the iodine depositions was measured in all containing slices in non-contrast-, arterial- and portal venous-phase CT scans, with a slice thickness of 5.00 mm. The mean density of the iodine deposition during the portal venous phase was subtracted from the mean density of the arterial phase to calculate the density changes (a positive enhancement score represents washout in the portal venous phase). In addition, a quotient relating to the non-contrast measurement was evaluated. RESULTS:Patients with a residual tumor displayed significantly higher enhancement scores in favor of density reduction between the arterial and portal venous phases, compared to patients without a residual tumor (1.41 ± 3.59, n = 14 vs. -13.97 ± 2.88, n = 16; p-value < 0.01). Furthermore, 87.75% of patients with an enhancement score higher than -1.00 (n = 9) had a residual tumor, whereas 100.00% of patients with an enhancement score lower than -20.00 (n = 6) were shown to be tumor-free. The enhancement score quotient resulted in similar findings. CONCLUSION:After cTACE in patients with hepatocellular carcinoma (HCC), the presence of a viable tumor correlated with enhancement scores based on the density measurements of iodine depositions in different phases of the CT scan. Low enhancement scores were associated with completely treated tumors and can aid the decision process to avoid possibly unnecessary angiographies

Memory-related hippocampal activity can be measured robustly using FMRI at 7 tesla

High field strength functional magnetic resonance imaging (fMRI) has developed rapidly. However, it suffers from increased artifacts in brain regions such as the medial temporal lobe (MTL), challenging functional imaging of the hippocampus with the objective of high-spatial resolution, which is particularly useful for this region both from a clinical and cognitive neuroscience perspective. We set out to compare a BOLD sequence at 7 T versus 3 T to visualize the MTL activity during an associative memory-encoding task. Twenty-eight healthy volunteers underwent a blocked-design fMRI at either 3 T or 7 T while performing a face-profession associative memory encoding task. Qualitative analyses of overall image quality revealed that functional images at 7 T were of high quality, showing a good white/gray matter contrast, with reasonably acceptable signal dropouts and artifacts at the lower portion of the temporal lobe. Analyses of task-related fMRI data revealed robust activations in the bilateral MTL during associative memory encoding at both field strengths. Notably, we observed significantly stronger memory-related hippocampal activation at 7 T than at 3 T, suggesting higher BOLD sensitivity at 7 T. These results are discussed in the light of the feasibility of 7 T scanning protocols for the MTL

7 Tesla MRI of microbleeds and white matter lesions as seen in vascular dementia

Purpose: To evaluate 7T MRI in the assessment of cerebrovascular alterations as seen in vascular dementia by means of detection of cerebral microbleeds (CMB) and depiction of white matter lesions (WML). 7T imaging was evaluated with respect to 1.5T. Materials and Methods: Ten healthy volunteers and 10 patients with CMBs and/or WMLs were examined at 1.5T and 7T using gradient-echo (T2*, SWI) and turbo-spin-echo sequences (FLAIR). Comparisons of image quality, CMB and WML detection rates between sequences and field strengths were performed. Results: Using high-resolution SWI at 7T 129 CMBs were detected compared to 75 at 1.5T using clinical SWI.With T2* at 7T 101 CMBs could be detected (33 CMBs at 1.5T). Lesion sizes were significantly larger for higher field strength. FLAIR images at 7T highlighted WMLs known from 1.5T with comparable extent. Gray and white matter contrast in FLAIR was slightly better at 1.5T, whereas image resolution and contrast of theWMLs to surrounding tissue was higher at 7T. Conclusion: By means of higher sensitivity for CMBs, 7T (SWI, T2*) might have significant impact on the early detection, diagnosis, and optimized antithrombotic therapy of cerebrovascular patients (eg, vascular dementia) in the future. Given the current state of technical development, 7T is approximately on par with 1.5T in the depiction of WMLs and their distribution, but holds the potential for future improvements

Novel implications in the treatment of hepatocellular carcinoma

Abstract Worldwide hepatocellular carcinoma remains one of the leading causes of cancer-related death, associated with a poor prognosis due to late diagnosis in the majority of cases. Physicians at care are frequently confronted with patients who are ineligible for curative treatment such as liver resection, transplantation or radiofrequency ablation. Besides established palliative locoregional therapies, such as ablation or chemoembolization, new treatment options, such as microwave ablation, drug-eluting bead transarterial chemoembolization or selective internal radiation therapy, are emerging; however, data from randomized controlled trials are still lacking. In order to achieve optimal tumor control, patients should receive tailored treatment concepts, considering their tumor burden, liver function and performance status, instead of strictly assigning patients to treatment modalities following algorithms that may be partly very restrictive. Palliative locoregional pretreatment might facilitate downstaging to ensure later curative resection or transplantation. In addition, the combined utilization of diff erent locoregional treatment options or systemic co-treatment has been the subject of several trials. In cases where local tumor control cannot be achieved, or in the scenario of extrahepatic spread, sorafenib remains the only approved systemic therapy option. Alternative targeted therapies, such as immune checkpoint inhibitors have shown encouraging preliminary results, while data from phase III studies are pending

Radioembolization with Y-90 Glass Microspheres: Do We Really Need SPECT-CT to Identify Extrahepatic Shunts?

Selective Internal Radiation Therapy (SIRT) with 90yttrium (Y-90) is an increasingly used therapeutic option for unresectable liver malignancies. Nontarget embolization of extrahepatic tissue secondary to vascular shunting can lead to SIRT associated complications. Our aim was to assess whether extrahepatic shunts can reliably be diagnosed based on hepatic digital subtraction angiography (DSA) or whether subsequent SPECT/CT data can provide additional information.825 patients with hepatocellular carcinoma (n = 636), hepatic metastases (n = 158) or cholangiocellular carcinoma (n = 31) were retrospectively analyzed. During hepatic DSA 128 arteries causing shunt flow to gastrointestinal tissue were coilembolized (right gastric artery n = 63, gastroduodenal artery n = 29; branches to duodenum / pancreas n = 36). Technectium-99m-labeled human serum albumin (HSA) was injected in all 825 patients. SPECT/CT data was used to identify additional or remaining shunts to extrahepatic tissue.An unexpected uptake of HSA in extrahepatic tissue was found by SPECT/CT in 54/825 (6.5%) patients (located in stomach n = 13, duodenum n = 26, distal bowel segments n = 12, kidney n = 1, diaphragm n = 2). These patients underwent repeated DSA and newly identified shunt vessels were coilembolized in 22/54 patients, while in 12/54 patients a more distal catheter position for repeat injection of HSA was chosen. In 20/54 patients the repeated SPECT/CT data still revealed an extrahepatic HSA uptake. These patients did not receive SIRT.Most extrahepatic shunts can be identified on DSA prior to Y-90 therapy. However, SPECT-CT data helps to identify additional shunts that were initially not seen on DSA

Vestibular effects of a 7 Tesla MRI examination compared to 1.5 T and 0 T in healthy volunteers.

Ultra-high-field MRI (7 Tesla (T) and above) elicits more temporary side-effects compared to 1.5 T and 3 T, e.g. dizziness or "postural instability" even after exiting the scanner. The current study aims to assess quantitatively vestibular performance before and after exposure to different MRI scenarios at 7 T, 1.5 T and 0 T. Sway path and body axis rotation (Unterberger's stepping test) were quantitatively recorded in a total of 46 volunteers before, 2 minutes after, and 15 minutes after different exposure scenarios: 7 T head MRI (n = 27), 7 T no RF (n = 22), 7 T only B0 (n = 20), 7 T in & out B0 (n = 20), 1.5 T no RF (n = 20), 0 T (n = 15). All exposure scenarios lasted 30 minutes except for brief one minute exposure in 7 T in & out B0. Both measures were documented utilizing a 3D ultrasound system. During sway path evaluation, the experiment was repeated with eyes both open and closed. Sway paths for all long-lasting 7 T scenarios (normal, no RF, only B0) with eyes closed were significantly prolonged 2 minutes after exiting the scanner, normalizing after 15 minutes. Brief exposure to 7 T B0 or 30 minutes exposure to 1.5 T or 0 T did not show significant changes. End positions after Unterberger's stepping test were significantly changed counter-clockwise after all 7 T scenarios, including the brief in & out B0 exposure. Shorter exposure resulted in a smaller alteration angle. In contrast to sway path, reversal of changes in body axis rotation was incomplete after 15 minutes. 1.5 T caused no rotational changes. The results show that exposure to the 7 Tesla static magnetic field causes only a temporary dysfunction or "over-compensation" of the vestibular system not measurable at 1.5 or 0 Tesla. Radiofrequency fields, gradient switching, and orthostatic dysregulation do not seem to play a role