Miriam Reichert's research while affiliated with Universität Mannheim and other places

Background: To analyse the influence of whole body (wb)-MRI on patient management compared to routine diagnostic tests in patients with fever of unknown origin (FUO). Methods: Twenty-four patients with FUO, defined as illness of more than three weeks with fever greater than 38.3 °C, underwent wb-MRI at a 1.5 T MR-system. The MR-protocol consisted of the following sequences: axial T1 VIBE, coronal T2-TIRM and a coronal echoplanar diffusion weighted sequence (overall acquisition time 29:39 min:s). Furthermore, laboratory findings, chest-x-ray, abdominal ultrasound, CT-scans and/or PET-CT scans were evaluated and compared to the wb-MRI findings in regard to treatment changes. Results: Wb-MRI yielded a correct diagnosis in 70% of the patients. In 46% the inflammatory focus was exclusively detected by wb-MRI. Focus detection by wb-MRI led to a subsequent change of the clinical management in 92% of the patients. In 6 patients both a wb-MRI and a PET-CT were performed yielding the correct diagnosis in the same 4 of 6 patients for both imaging modalities. Conclusions: Wb-MRI appears to be of value in the evaluation of FUO patients, allowing for optimized treatment by increasing diagnostic certainty. Due to its lack of nephrotoxicity and ionizing radiation it may be preferred over standard imaging techniques and PET-CT in the future. However, given the low number of patients in our trial, further prospective studies have to be performed to confirm our results.

Purpose To evaluate the usefulness of a novel MRI sequence strategy in the assessment of the periprosthetic anatomical structures after primary total knee arthroplasty. Methods Two MR sequences were retrospectively compared for the imaging of 15 patients with implanted cruciate-retaining/fixed-bearing TKAs (DePuy, PFC Sigma): a slice encoding sequence for metal artifact correction (SEMAC) and a standard sequence. Images were acquired on a 1.5-T system. The degree of artifact reduction was assessed using several qualitative (Likert-type scale) (artifact size, distorsion, blur, image quality, periprosthetic bone, posterior cruciate ligament, lateral collateral ligament, medial collateral ligament, patella tendon, popliteal vessels) and quantitative (artifact volume, Insall–Salvati index, length of patella/tendon, prosthesis dimensions) parameters by blinded reads performed by four investigators. The SEMAC sequences were statistically compared with the standard sequence using Wilcoxon test. Additionally, the intraclass correlation coefficient (ICC) for interobserver agreement was calculated. Results Higher levels of blurring were found with SEMAC compared to standard sequences (p < 0.001). All other qualitative parameters improved significantly with the application of SEMAC. In comparison with conventional sequences, the artifact volume was reduced by 59% utilizing SEMAC. Thus, the artifact reduction improved the precision of measurements such as Insall–Salvati index and length of patella/tendon (p < 0.001). The dimension of the tibial component (Ti alloy/polyethylene) revealed accurate values with both MRI sequences. A sufficient interobserver agreement among all readers was found with SEMAC, qualitatively ICC 0.9 (range 0.8–1) as well as quantitatively ICC 0.95 (range 0.92–0.98). Conclusions SEMAC effectively reduces artifacts caused by metallic implants after total knee arthroplasty relative to standard imaging. This allows for an improved assessment of periprosthetic anatomical structures. This might enable an improved detectability of postoperative complications in the future. Level of evidence Diagnostic Study Level III.

Aim: The purpose of this IRB-approved, retrospective study was to compare image quality between 2D and high-resolution 3D, T2-weighted (T2WI) magnetic resonance imaging (MRI) sequences and to investigate the additional value of ultra-high b-value diffusion-weighted imaging (DWI; b=2,000 mm/s2) for both rectal cancer staging and evaluating treatment response. Materials and methods: From 12 February to 24 August 2016, 26 consecutive patients (22 males, four females; mean age: 61.9±14.0 years) with histologically-proven rectal cancer. In total 31 examinations [12 prior to and 19 after chemoradiation (CRT)] were included. The patients underwent pelvic MRI on a 3.0-T scanner (Magnetom Skyra, Erlangen, Germany). Three radiologists (3, 4, and 5 years of experience in MRI, respectively) independently assessed all images and rated the image quality of DWI (b=800 mm/s2), apparent diffusion coefficient map, DWI (b=2,000 mm/s2), 3D sagittal T2WI, 3D axial T2WI, 2D sagittal T2WI, and 2D axial T2WI of each patient, respectively. In addition, signal intensity ratios (SIR) were calculated between rectal cancer and obturator internus muscle (background) in all patients after CRT on DWI (b=2,000 mm/s2) and correlated with histopathological regression grade (RG). Results: Tumor delineation was significantly better by 2D T2WI than 3D T2WI both before and after CRT (before CRT: Z=-3.2, p=0.02; after CRT: Z=-4.408, p<0.001; all: Z=-5.192; p<0.001) and was the preferred method, although image quality ratings were not significantly different (3D sagittal: 4.00±0.48; 2D sagittal: 4.03±0.34, p=0.713; 3D axial: 3.85±0.61, 2D axial: 3.78±0.64, p=0.537). Independent t-test showed significantly higher SIR between those with RG 1 or 2 (moderate response: mean score=2.02) and those with RG 3+4 (good response: mean score=0.8) (t=3.044, p=0.011). In those with RG 4 (complete response), SIR of b2000 was 0.946 compared to a 1.41 average of the whole cohort. In two patients, tumor was invisible on b2000 following CRT (RG 3 and 4, respectively). Interobserver agreement was mostly good (κ≥0.6) regarding image quality assessment, except for poor agreement (κ=0.4) in DWI (b2000) between the two less-experienced readers. Conclusion: In conclusion, 3D T2WI might be useful for evaluating response to neoadjuvant therapy in a comprehensive, cost-effective protocol, where 2D imaging seems to be preferable. In addition, DWI (b2000) may be beneficial in assessing both the primary and the residual tumor after CRT in rectal cancer and SIR may be helpful in assessing response to CRT.

Aim: To perform a quantitative, volumetric analysis of therapeutic effects of trans-arterial chemoembolization (TACE) in hepatocellular carcinoma (HCC) patients. Patients and methods: Entire tumor volume and a subset of hypervascular tumor portions were analyzed pre- and post-TACE in magnetic resonance imaging datasets of 22 HCC patients using a semi-automated segmentation and evaluation tool from the Medical Imaging Interaction Toolkit. Results were compared to mRECIST measurements and inter-reader variability was assessed. Results: Mean total tumor volume increased statistical significantly after TACE (84.6 ml pre- vs. 97.1 ml post-TACE, p=0.03) while hypervascular tumor volume decreased from 9.1 ml pre- to 3.7 ml post-TACE (p=0.0001). Likewise, mRECIST diameters decreased significantly after therapy (44.2 vs. 15.4 mm). In the inter-reader assessment, overlap errors were 12.3-17.7% for entire and 36.3-64.2% for the enhancing tumor volume. Conclusion: Quantification of therapeutic changes after TACE therapy is feasible using a semi-automated segmentation and evaluation tool. Following TACE, hypervascular tumor volume decreases significantly.

PURPOSE To compare metal artifact reduction after total knee arthroplasty in MRI at 1.5 T using novel MRI sequence strategies. METHOD AND MATERIALS Two sequences were compared for the imaging of metal implants after total knee arthroplasty on a 1.5 T MR system: a slice encoding sequence for metal artifact correction (SEMAC) and a standard TSE sequence. 15 patients with titanium implants were evaluated. Degree of artifact reduction was assessed quantitatively and qualitatively by both, artifact measurements and a blinded read. The images were ranked by the following parameters: artifact size, distortion, and the ability to differentiate bone marrow, cortex and soft tissue. The images were also evaluated in respect of the visibility of crucial and collateral ligaments and the patellar tendon. The Insall-Salvati-Index was measured as well. The SEMAC technique was compared directly to the TSE standard sequence. RESULTS In comparison to standard sequences artifact size was 59% less utilizing SEMAC. In terms of bone marrow, bone cortex and soft tissue visualization SEMAC was ranked superior to the corresponding standard sequence. Distortion was less with SEMAC. For the evaluation of blur, the standard images were ranked superior to the corresponding SEMAC sequence. In terms of overall image quality, SEMAC was ranked superior to the standard sequence. For all terms of clinical relevance SEMAC was ranked superior to the corresponding standard sequence. CONCLUSION SEMAC effectively reduces artifacts caused by metallic implants after total knee arthroplasty relative to standard imaging. CLINICAL RELEVANCE/APPLICATION SEMAC sequences allow for better visualisation of crucial anatomic structures after total knee arthroplasty thus improving evaluation of postoperative result and detection of postoperative complications.

Fragestellung: Die MR-Tomographie ist ein essentielles diagnostisches Instrument der modernen Orthopädie und Unfallchirurgie. Ohne die hochauflösende Darstellung weichteiliger Strukturen ist die Indikation zahlreicher aktueller operativer Therapien des Bewegungsapparates nicht mehr durchführbar. Die Versorgung mit metallischen Implantaten kann zu einer erheblichen Beeinträchtigung in der Beurteilbarkeit MR-Tomographischer Bilder führen. Solche Implantate haben eine sinnvolle postoperative MR-Bildgebung in vielen Fällen bisher weitgehend verhindert. Zweck dieser Arbeit ist es die Leistungsfähigkeit der SEMAC-Technik in solchen Fällen zu untersuchen. Methodik: Wir haben die Untersuchung von 16 mit TEP versorgten Kniegelenken und 18 instrumentierten Wirbelsäulen im 1,5 Tesla MRT unter Verwendung konventioneller und Slice-Encoding-Metall-Artifact-Correction (SEMAC - Siemens) Untersuchungssequenzen in einer prospektiven Kohortenstudie vorgenommen. Die Artefaktreduktion wurde anhand der folgenden Parameter verglichen: Artefaktgröße, Inter-Oberserver-Variabilität (2x FA Radiologie, 2x FA Orthopädie und Unfallchirurgie) in der Bild-Beurteilbarkeit und Abgrenzbarkeit anatomischer Strukturen. Ergebnisse und Schlussfolgerung: Im Vergleich der Artefaktgröße zwischen konventionellen und SEMAC Sequenzen zeigt sich eine deutliche Verringerung in den SEMAC-Sequenzen bei einliegenden Titan Implantaten im Bereich der Wirbelsäule. Bei einliegenden Chrom-Kobalt Implantaten am Knie zeigt sich sogar eine drastische Verbesserung der Bildqualität. Die Inter-Oberserver Variabilität zeigt eine hochsignifikante Überlegenheit der SEMAC-Sequenzen in ihrer Beurteilbarkeit gegenüber konventionellen MR-Sequenzen. Die Abgrenzbarkeit anatomischer Strukturen ist in der konventionellen MR-Tomographie nach Knie TEP erwartungsgemäß nicht abbildbar, nach Verwendung der SEMAC-Sequenzen ist morphologische Beurteilung der abgebildeten Strukturen möglich (z.B. klare Abgrenzbarkeit des hintere Kreuzbandes). Die Anwendung der SEMAC MR-Tomographie stellt eine deutliche Weiterentwicklung in der Bildgebung weichteiliger Strukturen bei Einliegen metallischer Implantate dar. Die Vorteile können bei der Beurteilung neurogener Strukturen nach Wirbelsäuleneingriffen klinische Relevanz erreichen. Nach Implantation von Knie TEP sind die Verbesserungen der Bildqualität, bei überwiegend Chrom-Cobalt-Stahlprothesen, so eklatant, dass neue klinische Fragestellungen aufgestellt werden können, welche einer bildgebenden Diagnostik bisher nicht zugänglich waren. Der dargestellte Fortschritt in der Bildgebung verlangt nach Etablierung weitere Studien zur Auslotung der Grenzen des Verfahrens. Die Korrelation der bildgebenden Ergebnisse mit klinischen Parametern muss Gegenstand nachfolgender Arbeiten werden.

Objective: To compare metal artefact reduction in MRI at both 3.0 T and 1.5 T using different sequence strategies. Methods: Metal implants of stainless steel screw and plate within agarose phantoms and tissue specimens as well as three patients with implants were imaged at both 1.5 T and 3.0 T, using view angle tilting (VAT), slice encoding for metal artefact correction with VAT (SEMAC-VAT) and conventional sequence. Artefact reduction in agarose phantoms was quantitatively assessed by artefact volume measurements. Blinded reads were conducted in tissue specimen and human imaging, with respect to artefact size, distortion, blurring and overall image quality. Wilcoxon and Friedman tests for multiple comparisons and intraclass correlation coefficient (ICC) for interobserver agreement were performed with a significant level of p < 0.05. Results: Compared with conventional sequences, SEMAC-VAT significantly reduced metal artefacts by 83% ± 9% for the screw and 89% ± 3% for the plate at 1.5 T; 72% ± 7% for the screw and 38% ± 13% for the plate at 3.0 T (p < 0.05). In qualitative analysis, SEMAC-VAT allowed for better visualization of tissue structures adjacent to the implants and produced better overall image quality with good interobserver agreement for both tissue specimen and human imaging (ICC = 0.80-0.99; p < 0.001). In addition, VAT also markedly reduced metal artefacts compared with conventional sequence, but was inferior to SEMAC-VAT. Conclusion: SEMAC-VAT and VAT techniques effectively reduce artefacts from metal implants relative to conventional imaging at both 1.5 T and 3.0 T. Advances in knowledge: The feasibility of metal artefact reduction with SEMAC-VAT was demonstrated at 3.0-T MR. SEMAC-VAT significantly reduced metal artefacts at both 1.5 and 3.0 T. SEMAC-VAT allowed for better visualization of the tissue structures adjacent to the metal implants. SEMAC-VAT produced consistently better image quality in both tissue specimen and human imaging.

Objective: To compare metal artefact reduction in MRI at both 3.0 T and 1.5 T using different sequence strategies. Methods: Metal implants of stainless steel screw and plate within agarose phantoms and tissue specimens as well as three patients with implants were imaged at both 1.5 T and 3.0 T, using view angle tilting (VAT), slice encoding for metal artefact correction with VAT (SEMAC-VAT) and conventional sequence. Artefact reduction in agarose phantoms was quantitatively assessed by artefact volume measurements. Blinded reads were conducted in tissue specimen and human imaging, with respect to artefact size, distortion, blurring and overall image quality. Wilcoxon and Friedman tests for multiple comparisons and intraclass correlation coefficient (ICC) for interobserver agreement were performed with a significant level of p < 0.05. Results: Compared with conventional sequences, SEMAC-VAT significantly reduced metal artefacts by 83% ± 9% for the screw and 89% ± 3% for the plate at 1.5 T; 72% ± 7% for the screw and 38% ± 13% for the plate at 3.0 T (p < 0.05). In qualitative analysis, SEMAC-VAT allowed for better visualization of tissue structures adjacent to the implants and produced better overall image quality with good interobserver agreement for both tissue specimen and human imaging (ICC = 0.80-0.99; p < 0.001). In addition, VAT also markedly reduced metal artefacts compared with conventional sequence, but was inferior to SEMAC-VAT. Conclusion: SEMAC-VAT and VAT techniques effectively reduce artefacts from metal implants relative to conventional imaging at both 1.5 T and 3.0 T. Advances in knowledge: The feasibility of metal artefact reduction with SEMAC-VAT was demonstrated at 3.0-T MR. SEMAC-VAT significantly reduced metal artefacts at both 1.5 and 3.0 T. SEMAC-VAT allowed for better visualization of the tissue structures adjacent to the metal implants. SEMAC-VAT produced consistently better image quality in both tissue specimen and human imaging.

Aim: Patients with acute alcohol intoxication present a serious and still growing problem for pre- and intra-hospital emergency services. Data on the clinical risk assessment of alcohol-intoxicated patients are sparse. The aim of the present work was, therefore, to collect and assess relevant risk parameters. Materials and Methods: At the Mannheim University Hospital, the medical records of 844 alcohol-intoxicated Emergency Department patients were retrospectively studied and evaluated. Results: The patients with alcohol intoxications were predominantly males with an average age of 45 years. Mean blood alcohol concentration was 0.28%. The rate of haemodynamic, respiratory or metabolic complications in these patients was low. In 43% of cases, there was moderately to severely impaired consciousness. About half of the patients were treated on an outpatient basis. Conclusion: Our data demonstrate a low clinical risk for alcohol-intoxicated patients. Nevertheless, it is necessary to provide a defined monitoring standard in order to also be prepared for the few potential complications of alcohol intoxication and the possible differential diagnoses of impaired consciousness. Copyright © 2015 International Institute of Anticancer Research (Dr. John G. Delinassios), All rights reserved.

Fragestellung: Die primäre Knieendoprothetik ist ein ausgesprochen erfolgreiches und gleichermaßen etabliertes Verfahren in der Behandlung fortgeschrittener Kniegelenkbeschwerden. Die Therapie der sekundär auftretenden Fehlfunktion nach Knie-TEP hingegen, ist von deutlich niedrigeren Erfolgsraten gekennzeichnet. Dies ist nicht zuletzt auf die geringe Sicherheit der präoperativen Diagnosen bei reduzierten Möglichkeiten der bildgebenden Diagnostik zurückzuführen. Beispielhaft ist die symptomatische sagittale Instabilität nach Knie TEP zu nennen. Differentialdiagnostisch lässt sich in solchen Fällen der Inlay Aufbrauch, vom Versagen des hinteren Kreuzbandes oder der Kombination aus beidem abgrenzen. Die Röntgendiagnostik ist in diesen Fällen lediglich in der Lage indirekte Hinweise auf eine zu Grunde liegende Pathologie abzubilden. Aussagekräftigere, hochauflösende bildgebende Verfahren sind derzeit nicht verfügbar, da die Anwendbarkeit der MRT Untersuchung aufgrund von Metallartefaktbildung großen Einschränkungen unterliegt. Zweck dieser Arbeit ist es, zu untersuchen ob die Darstellung von Knie Binnenstrukturen im MRT bei einliegender Kobalt-Chrom (CoCr) Knie-TEP unter Verwendung einer Slice-Encoding-Metall-Artifact-Correction (SEMAC) Sequenz erreicht werden kann. Methodik: Hierzu wurden sieben symptomatische Patienten mit einliegender CoCr Knie-TEP ausgewählt und mit der genannten neuen MRT Sequenz untersucht. Die hieraus analog zur konventionellen MR-Tomographie berechneten Bilddatensätze und die nach dem SEMAC-Algorithmus erstellten Datensätze wurden hinsichtlich der erreichten Beurteilbarkeit des hinteren Kreuzbandes bewertet. Ergebnisse und Schlussfolgerung: Die Auswertung der Daten bestätigte das erwartete Fehlen einer Abbildbarkeit des hinteren Kreuzbandes in konventionell gewonnenen MRT-Daten. Gleichzeitig konnte anhand der mit SEMAC-Sequenzen generierten MRT Daten eine eindrückliche strukturelle Beurteilbarkeit des gesamten HKB vom femoralen Ursprung bis zum tibialen Ansatz aufgezeigt werden. Die vorliegenden Ergebnisse belegen damit die technische Möglichkeit, das hintere Kreuzband trotz einliegender CoCr Knie-TEP mit der MRT abzubilden. Die Korrelation des bildgebenden Nachweises eines intakten HKB mit der funktionellen Wertigkeit der abgebildeten Struktur ist noch Gegenstand biomechanischer Arbeiten. Vor dem Hintergrund der immer noch steigenden Zahlen an Knie Prothesen Revisionen und der bisher alternativlosen Diagnostik, erscheint die weitere Untersuchung der Validität dieser Methode wertvoll.