J Luetkens

Proton density fat fraction (PDFF) MRI for differentiation of benign and malignant vertebral lesions

ObjectivesTo investigate whether proton density fat fraction (PDFF) measurements using a six-echo modified Dixon sequence can help to differentiate between benign and malignant vertebral bone marrow lesions.MethodsSixty-six patients were prospectively enrolled in our study. In addition to conventional MRI at 3.0-Tesla including at least sagittal T2-weighted/spectral attenuated inversion recovery and T1-weighted sequences, all patients underwent a sagittal six-echo modified Dixon sequence of the spine. The mean PDFF was calculated using regions of interest and compared between vertebral lesions. A cut-off value of 6.40% in PDFF was determined by receiver operating characteristic curves and used to differentiate between malignant (< 6.40%) and benign (≥ 6.40%) vertebral lesions.ResultsThere were 77 benign and 44 malignant lesions. The PDFF of malignant lesions was statistically significant lower in comparison with benign lesions (p < 0.001) and normal vertebral bone marrow (p < 0.001). The areas under the curves (AUC) were 0.97 for differentiating benign from malignant lesions (p < 0.001) and 0.95 for differentiating acute vertebral fractures from malignant lesions (p < 0.001). This yielded a diagnostic accuracy of 96% in the differentiation of both benign lesions and acute vertebral fractures from malignancy.ConclusionPDFF derived from six-echo modified Dixon allows for differentiation between benign and malignant vertebral lesions with a high diagnostic accuracy.Key Points• Establishing a diagnosis of indeterminate vertebral lesions is a common clinical problem• Benign bone marrow processes may mimic the signal alterations observed in malignancy• PDFF differentiates between benign and malignant lesions with a high diagnostic accuracy• PDFF of non-neoplastic vertebral lesions is significantly higher than that of malignancy• PDFF from six-echo modified Dixon may help avoid potentially harmful bone biopsy

Proton density fat fraction (PDFF) MR imaging for differentiation of acute benign and neoplastic compression fractures of the spine

ObjectivesTo evaluate the diagnostic performance of proton density fat fraction (PDFF) magnetic resonance imaging (MRI) to differentiate between acute benign and neoplastic vertebral compression fractures (VCFs).MethodsFifty-seven consecutive patients with 46 acute benign and 41 malignant VCFs were prospectively enrolled in this institutional review board approved study and underwent routine clinical MRI with an additional six-echo modified Dixon sequence of the spine at a clinical 3.0-T scanner. All fractures were categorised as benign or malignant according to either direct bone biopsy or 6-month follow-up MRI. Intravertebral PDFF and PDFFratio (fracture PDFF/normal vertebrae PDFF) for benign and malignant VCFs were calculated using region-of-interest analysis and compared between both groups. Additional receiver operating characteristic and binary logistic regression analyses were performed.ResultsBoth PDFF and PDFFratio of malignant VCFs were significantly lower compared to acute benign VCFs [PDFF, 3.48 ± 3.30% vs 23.99 ± 11.86% (p < 0.001); PDFFratio, 0.09 ± 0.09 vs 0.49 ± 0.24 (p < 0.001)]. The areas under the curve were 0.98 for PDFF and 0.97 for PDFFratio, yielding an accuracy of 96% and 95% for differentiating between acute benign and malignant VCFs. PDFF remained as the only imaging-based variable to independently differentiate between acute benign and malignant VCFs on multivariate analysis (odds ratio, 0.454; p = 0.005).ConclusionsQuantitative assessment of PDFF derived from modified Dixon water-fat MRI has high diagnostic accuracy for the differentiation of acute benign and malignant vertebral compression fractures.Key Points• Chemical-shift-encoding based water-fat MRI can reliably assess vertebral bone marrow PDFF• PDFF is significantly higher in acute benign than in malignant VCFs• PDFF provides high accuracy for differentiating acute benign from malignant VCFs

Frühzeitige Überlebenszeitstratifikation durch Diffusionsbildgebung nach SIRT bei kolorektalen Lebermetastasen

Zielsetzung: Grosenbasierte Verfahren zur Therapieerfolgsmessung lokal interventioneller Therapieverfahren, z.B. RECIST, konnen ein fruhes Therapieansprechen haufig nur unzureichend erfassen. Aktuelle Studienergebnisse weisen darauf hin, dass die MRT-Diffusionsbildgebung (DWI) ein Therapieansprechen bereits vor morphologisch fassbaren Anderungen aufzeigt. Ziel dieser Studie war es daher zu prufen, ob sich die DWI mittels quantitativer Analyse des Diffusionskoeffizienten (ADC) zur fruhen Vorhersage des Gesamtuberlebens (OS) von Patienten mit hepatisch metastasiertem kolorektalem Karzinom nach selektiver interner Radiotherapie (SIRT) eignet. Material und Methodik: 41 Patienten erhielten 19 ± 16 Tage vor und 36 ± 10 Tage nach SIRT mit 90Y-Mikrospharen eine MRT Untersuchung mit DWI (1.5T, Philips Intera). Pra- und posttherapeutische Minimum ADC-Werte (b = 0, 50, 800) wurden in den 3 grosten Lebermetastasen im Behandlungsareal gemessen, gemittelt und verglichen. Mittels Kaplan-Meier-(log-rank-Test) und multivariater Cox-Regressionsanalyse wurde untersucht, ob ein posttherapeutischer ADC-Anstieg prognostische Aussagekraft fur das OS besitzt. Weitere untersuchte Einflussfaktoren auf das OS waren Alter, Geschlecht, Karnofsky-Score, Bilirubin, hepatische Tumorlast und das Vorhandensein extrahepatischer Metastasen. Ergebnisse: Das mediane OS nach Therapie betrug 8 Monate. Patienten mit ADC-Anstieg ≥0% nach SIRT wiesen ein deutlich verlangertes medianes OS als Patienten mit ADC-Reduktion auf (18 vs. 4 Monate; p < 0.001). Weiterhin hatten hepatische Tumorlast ≥50% (6 vs. 8 Monate; p = 0.025) und die applizierte Dosis ≥2 Gy (5 vs. 10 Monate; p = 0.048) einen signifikanten Einfluss auf das OS. In der multivariaten Analyse verblieb das Nichtvorhandensein eines posttherapeutischen ADC-Anstiegs ≥0% als einziger signifikanter und unabhangiger Risikofaktor zur Pradiktion des OS (p < 0.001). Schlussfolgerungen: Die DWI erlaubt eine Einschatzung des Therapieansprechens bereits wenige Wochen nach SIRT und ermoglicht damit eine fruhzeitige Uberlebenszeitstratifikation.

Pulmonary arterial hypertension is associated with increased T1 relaxation times and decreased left ventricular performance in spite of preserved left ventricular function

Background Pulmonary arterial hypertension (PAH) mainly affects the right (RV). Due to ventricular interdependence, PAH may also affect the left ventricle (LV) leading to opposite adaptive changes with an LV-atrophy and diffuse fibrosis. Strain analysis detects ventricular dysfunction even in patients with preserved ventricular function. Cardiac magnetic resonance (CMR) mapping techniques with determination of T1 and T2 relaxation times (T1 resp T2) may allow for discrimination between healthy myocardium and diffuse fibrosis in PAH patients. This study was performed to evaluate the association between myocardial changes assessed by strain analysis, and by native T1 and T2 map in patients with PAH.

Epicardial adipose tissue, aortic stiffness and myocardial fibrosis in healthy individuals: a quantitative cardiac magnetic resonance study

Background Epicardial adipose tissue, aortic stiffness and myocardial fibrosis have been linked to cardiovascular risk and disease; however, often different modalities are used for their measurement. Cardiac magnetic resonance (CMR) may be used to determine these parameters in a single examination by the measurement of epicardial fat volumes (EFV), aortic pulse wave velocity (PWV) as a parameter of aortic stiffness, and T1-relaxation time (T1) as a marker for myocardial fibrosis. This quantitative CMR-study was performed to identify relationships between these parameters in healthy individuals and to correlate them with age, body mass index (BMI) and gender.