Variability of MRI Aortic Stiffness Measurements in a Multicenter Clinical Trial Setting: Intraobserver, Interobserver, and Intracenter Variability of Pulse Wave Velocity and Aortic Strain Measurement

PURPOSE

To assess intraobserver, interobserver, and scan-rescan variability of MRI aortic stiffness measurements in a multicenter trial setting.

MATERIALS AND METHODS

This study was a retrospective analysis of prospectively collected data in a multicenter prospective clinical trial (clinicaltrials.gov ID NCT01870739). Forty-five adult patients (31 men; mean age, 58 years ± 12 [standard deviation]; 15 patients per center; three centers) with arterial hypertension underwent standardized 3-T baseline MRI assessments between June and September 2014. Aortic strain was calculated from maximum and minimum aortic area measurements repeated three times by three readers at three aortic levels on three retrospectively gated axial gradient-echo (GRE) data sets. Pulse wave velocity (PWV) was assessed three times by five readers as Δx/Δt: Δx was measured on a parasagittal GRE image of the aortic arch, and Δt was extracted from ascending and descending aortic velocity curves created on three axial phase-contrast acquisitions. Intraobserver, interobserver, and scan-rescan variability was calculated using percentage coefficient of variation (COV).

RESULTS

Aortic strain variability was lowest at the level of the distal descending aorta (DDA) with median COVs of 1.6% for intraobserver variability, 4.0% for interobserver variability, and 10.3% for scan-rescan variability. It was highest at the ascending aorta (AA) with COVs of 3.6% for intraobserver variability, 10.7% for interobserver variability, and 19.8% for scan-rescan variability. Variability of PWV was low: 0.7% for intraobserver variability, 1.5% for interobserver variability, and 8.1% for scan-rescan variability.

CONCLUSION

Low variability can be achieved for aortic strain and PWV measurements in a multicenter trial setting using standardized MRI protocols. Although COV was lower when measuring aortic strain at DDA compared with AA, variability was acceptable at both anatomic locations.Supplemental material is available for this article.© RSNA, 2020.

[Rational imaging of hepatocellular carcinoma. The challenge of multimodal diagnostic criteria]

CLINICAL/METHODICAL ISSUE

Both computed tomography (CT) and magnetic resonance imaging (MRI) constitute the gold standard in radiological imaging of hepatocellular carcinoma (HCC). In cases of typical contrast behavior each modality as a single dynamic technique allows the diagnosis of HCC. There is still a challenge in detection of small HCCs < 2 cm, in differentiating HCC and high-grade dysplasia from other benign liver lesions as well as the evaluation of hypovascular liver lesions in the cirrhotic liver.

PERFORMANCE

Nowadays, both modalities achieve high detection rates of 90-100 % for lesions > 2 cm. Regarding lesions between 1 and 2 cm there is a higher sensitivity for MRI ranging between 80 and 90 % compared to 60-75 % with CT. Besides the multimodal diagnostic criteria, MRI provides significant benefits with the use of hepatobiliary contrast. Especially in combination with diffusion- weighted imaging (DWI) increased sensitivity and diagnostic accuracy compared to CT has been described for lesions sized < 2 cm. Regarding the differentiation from other hepatic nodules in the cirrhotic liver there is strong evidence that the coexistence of arterial enhancement and hypointensity on hepatobiliary imaging is specific for HCC. Moreover, hypointensity on hepatobiliary imaging is associated with a high positive predictive value (PPV) of up to 100 % for the presence of high-grade dysplasia and HCC.

ACHIEVEMENTS

The use of MRI including hepatobiliary imaging and DWI has to be regarded as the best non-invasive imaging modality for the detection of HCC and for the characterization of nodules in patients with liver cirrhosis. In comparison to CT there are benefits regarding detection of small lesions < 2 cm and evaluation of hypovascular liver lesions in the context of the hepatocarcinogenesis including prognostic values of premalignant lesions.

PRACTICAL RECOMMENDATIONS

Both MRI and CT provide a high diagnostic performance in evaluation of HCC in liver cirrhosis. With MRI there are considerable advantages regarding the detection rate and specificity. For daily clinical routine, CT offers a fast, reliable and easy available modality with benefits for patients in reduced general state of health and restricted compliance.

A very rare cause of low-back pain and sciatica: deep vein thrombosis due to absence of the inferior vena cava mimicking the clinical and radiological signs of lumbar disc herniation

The authors report a very rare cause of low-back pain and sciatica in a patient with iliac vein thrombosis attributed to absence of the infrarenal segment of the inferior vena cava (IVC) with massively dilated venous collaterals draining via a paraspinal plexus into the azygous system. This 21-year-old man presented with acute low-back pain radiating to the left ventral thigh. The initial CT scan revealed an intraspinal lesion that mimicked lumbar disc herniation. Further clarification revealed an iliac vein thrombosis, which was triggered by the absence of the infrarenal segment of the IVC, a very rare vascular anomaly. Collateral venous return was developed and led to lumbar varicosities and epidural vein engorgements. Laboratory examinations revealed factor V mutation as a predisposing factor for thrombosis. The patient's symptoms were relieved with anticoagulation and antiinflammatory therapy. Absence of the infrarenal IVC associated with iliac vein thrombosis should be regarded as a very rare cause of radicular and low-back pain, and this condition can mimic the clinical and radiological signs of lumbar disc herniation. Sciatica might be the first clinical manifestation of this rare venous anomaly.

Protective effects of ischemic preconditioning and application of lipoic acid prior to 90 min of hepatic ischemia in a rat model

AIM: To compare different preconditioning strategies to protect the liver from ischemia/reperfusion injury focusing on the expression of pro- and anti-apoptotic proteins. Interventions comprised different modes of ischemic preconditioning (IP) as well as pharmacologic pretreatment by α-lipoic acid (LA).

METHODS: Several groups of rats were compared: sham operated animals, non-pretreated animals (nt), animals receiving IP (10 min of ischemia by clamping of the portal triad and 10 min of reperfusion) prior to sustained ischemia, animals receiving selective ischemic preconditioning (IPsel, 10 min of ischemia by selective clamping of the ischemic lobe and 10 min of reperfusion) prior to sustained ichemia, and animals receiving 500 μmol α-LA injected i.v. 15 min prior to the induction of 90 min of selective ischemia.

RESULTS: Cellular damage was decreased only in the LA group. TUNEL-positive hepatocytes as well as necrotic hepatocyte injury were also decreased only by LA (19 ± 2 vs 10 ± 1, P < 0.05 and 29 ± 5 vs 12 ± 1, P < 0.05). Whereas caspase 3- activities in liver tissue were unchanged, caspase 9- activity in liver tissue was decreased only by LA pretreatment (3.1 ± 0.3 vs 1.8 ± 0.2, P < 0.05). Survival rate as the endpoint of liver function was increased after IP and LA pretreatment but not after IPsel. Levels of lipid peroxidation (LPO) in liver tissue were decreased in the IP as well as in the LA group compared to the nt group. Determination of pro- and anti-apoptotic proteins showed a shift towards anti-apoptotic proteins by LA. In contrast, both our IP strategies failed to influence apototic cell death.

CONCLUSION: IP, consisting of 10 min of ischemia and 10 min of reperfusion, protects only partly against ischemia/reperfusion injury of the liver prior to 90 min of selective ischemia. IPsel did not influence ischemic tolerance of the liver. LA improved tolerance to ischemia, possibly by downregulation of pro-apoptotic Bax.

Protection from hepatic ischemia/reperfusion injury and improvement of liver regeneration by alpha-lipoic acid

The aim of this study was to characterize the in vivo action of lipoic acid (LA) in hepatic ischemia/reperfusion injury (IRI) and its effects on liver regeneration involving the investigation of mechanisms of action and effects on animal survival. Two groups of rats were compared: one group received 500 micromol alpha-LA injected via the inferior vena cava 15 min before the induction of 90 min of selective ischemia. The untreated group received vehicle. Influence of LA on IRI of the liver was determined in short- and long-term experiments. Cellular damage was decreased under preconditioning conditions with LA. Caspase 3, 8, and 9 activities were significantly lower in the LA group accompanied by a decrease in terminal deoxynucleotidyl transferase-mediated dUTP nick-end labeling-positive hepatocytes. Electron micrographs in the untreated group showed massive mitochondrial damage. The survival rate as end point of liver function was markedly increased after pretreatment with LA. Increased levels of tumor necrosis factor alpha was shown by enzyme-linked immunosorbent assay as well as real-time reverse transcription-polymerase chain reaction in the LA group accompanied by increased mitotic index and Ki-67 staining in liver tissue. Attenuation of IRI of the rat liver in vivo by LA is accompanied by reduction of necrosis and apoptosis-related cell death, whereas liver regeneration is increased.

Reduction of ischemia reperfusion injury after liver resection and hepatic inflow occlusion by α-lipoic acid in humans

AIM: To evaluate the protective effects of preconditioning by α-lipoic acid (LA) in patients undergoing hepatic resection under inflow occlusion of the liver.

METHODS: Twenty-four patients undergoing liver resection for various reasons either received 600 mg LA or NaCl 15 min before transection performed under inflow occlusion of the liver. Blood samples and liver wedge biopsy samples were obtained after opening of the abdomen immediately after inflow occlusion of the liver, and 30 min after the end of inflow occlusion of the liver.

RESULTS: Serum levels of aspartate transferase and alanine transferase were reduced at all time points in patients who received LA in comparison to those who received NaCL. This was accompanied by reduced histomorphological features of oncosis. We observed TUNEL-positive hepatocytes in the livers of the untreated patients, especially after 30 min of ischemia. LA attenuated this increase of TUNEL-positive hepatocytes. Under preconditioning with LA, ATP content was significantly enhanced after 30 min of ischemia and after 30 min of reperfusion.

CONCLUSION: This is the first report on the potential for LA reducing ischemia/reperfusion injury (IRI) of the liver in humans who were undergoing liver surgery. Beside its simple and rapid application, side effects did not occur. LA might therefore represent a new strategy against hepatic IRI in humans.

Different protection mechanisms after pretreatment with glycine or alpha-lipoic acid in a rat model of warm hepatic ischemia

BACKGROUND/AIM

Alpha-lipoic (LA) acid pretreatment has previously been described to reduce ischemia/reperfusion injury (IRI) after warm liver ischemia, whereas glycine pretreatment has been shown to be protective mostly in models of cold hepatic ischemia. The aim of this study was to determine whether glycine decreases IRI after warm hepatic ischemia. Furthermore we investigated whether doses of LA other than those used previously are also protective against IRI after warm hepatic ischemia.

METHODS

Selective liver ischemia was maintained over a period of 90 min. In long-term as well as short-term experiments we studied IRI in several groups comparing animal survival as the pivotal endpoint.

RESULTS

Animal survival was improved by glycine and 5,000 micromol LA, whereas all animals died within 3 days after pretreatment with 50 micromol LA. In the glycine group we observed a tendency towards decreased apoptosis-related cell death measured by the activity of caspase-3 in liver tissue and the percentage of TUNEL-positive hepatocytes in comparison to the untreated group. Serum alpha-glutathione S-transferase, lipid peroxidation, and caspase-3 activity as well as the percentage of TUNEL-positive hepatocytes and the percentage of liver necrosis were only significantly decreased by 5,000 micromol LA pretreatment. Liver tissue levels of tumor necrosis factor (TNF)alpha were reduced only in the glycine group whereas TNFalpha was increased in the untreated as well as the LA group. Levels of TNFalpha mRNA were upregulated in both the glycine- and LA-pretreated groups.

CONCLUSION

Our data show that increased animal survival by glycine was accompanied by a reduced TNFalpha content in liver tissue. Protection by glycine is likely to result from a reduction in adverse TNFalpha effects. Administration of high-dose LA on the other hand led to a significant reduction in necrosis- and apoptosis-related cell death in IRI of the liver without a reduction in liver TNFalpha.

Quantitative data analysis for exploring outcomes in cardiac surgery

The article focuses on possibilities of statistical knowledge exploration to predict outcomes of surgical treatments. The outcomes were defined in relation to the measured peri- and intraoperative data, as well as follow-up patient questionnaire. Clinical consequences are expected in terms of a smaller data set with a better ability to predict the surgery outcomes and a better cost performance. The important questions that could discriminate quality of life (QoL) were: Relief from surgery?, Has cardiac surgery effected earlier symptoms? Work capacity? Consultations after the surgery? The performed data analysis proved to be efficient in the complex data set that was collected. Pain relief was identified to be significant, while relations between measured blood laboratory profile and later QoL were weak.

Knowledge representation forms for data mining methodologies as applied in thoracic surgery

Typical ways of disseminating and using results of clinical research are scientific journals and reports. Presentation forms are condensed and comprehensible mainly to the experts following the specific topics. A vast amount of information remains unutilized due to the complex form of presenting the knowledge. Subject of this research is to explore possibilities of representation and also visualization of the results obtained using data mining methodologies. The intention is to formulate more than scientific ways to communicate facts that are of interest for the clinicians, medical students and even patients. Internet technologies as already widely established media support knowledge representation forms such as hypertext documents and structured knowledge components. The "Assist Me" decision support system for surgical treatment of cardiac patients integrates several forms of data mining and representation methodologies. We are showing a feasibility study in which scientific outcomes were forwarded to a broad group of potential users.

[Primary amyloidosis with nephrotic syndrome: 5 year follow-up under polychemotherapy. A case report (author's transl)]

A patient with primary amyloidosis had infiltration of liver, bone and bone marrow and a nephrotic syndrome with massive proteinuria. In addition, there was evidence for a plasma cell dyscrasia with an increased number of plasma cells and other lymphoreticular cell elements in the bone marrow and an impairment of immunoglobulin synthesis without M-gradient. The course of disease was observed over a period of five years. The patient was treated intermittently with a combination of penicillamine, melphalan, fluocortolone and fluoxymesterone. Under treatment the nephrotic syndrome disappeared and liver size decreased. Hemopoiesis remained sufficient but bone marrow infiltration by amyloid did not respond to therapy and massive osteoporosis developed. Comparison of our with other reported cases treated with the same regime suggests that response to this treatment may be influenced by factors such as sex and clinical manifestation of the disease.

[CT for staging of systemic lymphatic diseases (author's transl)]

In 75 patients with lymphoma (46 Hodgkin's disease, 29 non-Hodgkin lymphomas) computed tomography was performed in order to detect neoplastic invasion of the abdominal organs (55 new cases) or to control the results of treatment (20 cases). In 30 cases enlarged retroperitoneal or mesenteric lymphnodes and/or liver or spleen enlargement were found. Neoplastic involvement of lymphnodes without enlargement was missed in two cases. CT failed also to demonstrate microscopic malignant invasion of liver and spleen. The false-negative rate in our series was 10.9%. Computed tomography is a non-invasive method which is very well suited for staging malignant lymphoma.