Dariusch R. Hadizadeh

High temporal and high spatial resolution MR angiography (4D-MRA)

In the first decade of the twenty-first century, whole-body magnetic resonance scanners with high field strengths (and thus potentially better signal-to-noise ratios) were developed. At the same time, parallel imaging and echo-sharing techniques were refined to allow for increasingly high spatial and temporal resolution in dynamic magnetic resonance angiography (time-resolvedu200a=u200aTR-MRA). This technological progress facilitated tracking the passage of intra-venously administered contrast agent boluses as well as the acquisition of volume data sets at high image refresh rates (4D-MRA). This opened doors for many new applications in non-invasive vascular imaging, including simultaneous anatomic and functional analysis of many vascular pathologies including arterio-venous malformations. Different methods were established to acquire 4D-MRA using various strategies to acquire k-space trajectories over time in order to optimize imaging according to clinical needs. These include keyhole-based techniques (e.u200ag. 4D-TRAK), TRICKS - both with and without projection - and HYPR-reconstruction, TREAT, and TWIST. Some of these techniques were first introduced in the 1980u200as and 1990u200as, were later enhanced and modified, and finally implemented in the products of major vendors. In the last decade, a large number of studies on the clinical applications of TR-MRA was published. This manuscript provides an overview of the development of TR-MRA methods and the 4D-MRA techniques as they are currently used in the diagnosis, treatment and follow-up of vascular diseases in various parts of the body.

Image and Diagnosis Quality of X-Ray Image Transmission via Cell Phone Camera: A Project Study Evaluating Quality and Reliability

Introduction Developments in telemedicine have not produced any relevant benefits for orthopedics and trauma surgery to date. For the present project study, several parameters were examined during assessment of x-ray images, which had been photographed and transmitted via cell phone. Materials and Methods A total of 100 x-ray images of various body regions were photographed with a Nokia cell phone and transmitted via email or MMS. Next, the transmitted photographs were reviewed on a laptop computer by five medical specialists and assessed regarding quality and diagnosis. Results Due to their poor quality, the transmitted MMS images could not be evaluated and this path of transmission was therefore excluded. Mean size of transmitted x-ray email images was 394 kB (range: 265–590 kB, SD ±59), average transmission time was 3.29 min ±8 (CI 95%: 1.7–4.9). Applying a score from 1–10 (very poor - excellent), mean image quality was 5.8. In 83.2±4% (mean value ± SD) of cases (median 82; 80–89%), there was agreement between final diagnosis and assessment by the five medical experts who had received the images. However, there was a markedly low concurrence ratio in the thoracic area and in pediatric injuries. Discussion While the rate of accurate diagnosis and indication for surgery was high with a concurrence ratio of 83%, considerable differences existed between the assessed regions, with lowest values for thoracic images. Teleradiology is a cost-effective, rapid method which can be applied wherever wireless cell phone reception is available. In our opinion, this method is in principle suitable for clinical use, enabling the physician on duty to agree on appropriate measures with colleagues located elsewhere via x-ray image transmission on a cell phone.

Diffusion-weighted magnetic resonance imaging predicts survival in patients with liver-predominant metastatic colorectal cancer shortly after selective internal radiation therapy

AbstractObjectivesTo investigate whether quantifications of apparent diffusion coefficient (ADC) on diffusion-weighted imaging (DWI) can predict overall survival (OS) in patients with liver-predominant metastatic colorectal cancer (CRC) following selective internal radiation therapy with 90Yttrium-microspheres (SIRT).MethodsForty-four patients underwent DWI 19u2009±u200916xa0days before and 36u2009±u200910xa0days after SIRT. Tumour-size and intratumoral minimal ADC (minADC) values were measured for 132 liver metastases on baseline and follow-up DWI. Optimal functional imaging response to treatment was determined by receiver operating characteristics and defined as ≥22xa0% increase in post-therapeutic minADC. Survival analysis was performed with the Kaplan-Meier method and Cox-regression comparing various variables with potential impact on OS.ResultsMedian OS was 8xa0months. The following parameters were significantly associated with median OS: optimal functional imaging response (18 vs. 5xa0months; pu2009<u20090.001), hepatic tumour burden <50xa0% (8 vs. 5xa0months; pu2009=u20090.018), Eastern Cooperative Oncology Group performance scale <1 (10 vs. 4xa0months; pu2009=u20090.012) and progressive disease according to Response and Evaluation Criteria in Solid Tumours (8 vs. 3xa0months; pu2009=u20090.001). On multivariate analysis, optimal functional imaging response and hepatic tumour burden remained independent predictors of OS.ConclusionFunctional imaging response assessment using minADC changes on DWI may predict survival in CRC shortly after SIRT.Key points• Relative minADC changes may predict survival in liver-predominant metastatic colorectal cancer following SIRTn • Intratumoral minADC changes by ≥22u2009% were best to predict an improved overall survivaln • Functional imaging response assessment is feasible before anatomic tumour-size changes occurn • minADC changes might guide future therapy management in sequential lobar radioembolization approaches

The Whole Spectrum of Alcohol-Related Changes in the CNS: Practical MR and CT Imaging Guidelines for Daily Clinical Use

UNLABELLEDnAlcohol addiction is the most common drug addiction. Alcohol passes both the placenta as well as the blood-brain barrier and is in multiple ways neurotoxic. Liver diseases and other systemic alcohol-related diseases cause secondary damage to the CNS. Especially in adolescents, even a single episode of severe alcohol intoxication (binge drinking) may result in life-threatening neurological consequences. Alcohol-related brain and spinal cord diseases derive from multiple causes including impairment of the cellular metabolism, often aggravated by hypovitaminosis, altered neurotransmission, myelination and synaptogenesis as well as alterations in gene expression. Modern radiological diagnostics, MRI in particular, can detect the resulting alterations in the CNS with a high sensitivity. Morphological aspects often strongly correlate with clinical symptoms of the patient. It is less commonly known that many diseases considered as typically alcohol-related, such as Wernickes encephalopathy, are to a large extent not alcohol-induced. Visible CNS alterations are thus non-pathognomonic and demand careful evaluation of differential diagnoses. This review article elucidates the pathogenesis, clinical aspects and radiological image features of the most common alcohol-related CNS diseases and their differential diagnoses.nnnKEY POINTSnAlcohol-associated changes in the CNS are common and radiologically assessable. They are often subtle and allow multiple differential diagnoses besides alcohol consumption. Knowledge of clinical exams and lab results is crucial for diagnostic accuracy.

Biopsy targeting with dynamic contrast-enhanced versus standard neuronavigation MRI in glioma: a prospective double-blinded evaluation of selection benefits

Current biopsy planning based on contrast-enhanced T1W (CET1W) or FLAIR sequences frequently delivers biopsy samples that are not in concordance with the gross tumor diagnosis. This study investigates whether the quantitative information of transfer constant Ktrans maps derived from T1W dynamic contrast-enhanced MRI (DCE-MRI) can help enhance the quality of biopsy target selection in glioma. 28 patients with suspected glioma received MRI including DCE-MRI and a standard neuronavigation protocol of 3D FLAIR- and CET1W data sets (0.1xa0mmol/kg gadobutrol) at 3.0xa0T. After exclusion of five cases with no Ktrans-elevation, 2–6 biopsy targets were independently selected by a neurosurgeon (samples based on standard imaging) and a neuroradiologist (samples based on kinetic parameter Ktrans) per case and tissue samples corresponding to these targets were collected by a separate independent neurosurgeon. Standard technique and Ktrans-based samples were rated for diagnostic concordance with the gross tumor resection reference diagnosis (67 WHO IV; 24 WHO III and II) by a neuropathologist blinded for selection mode. Ktrans-based sample targets differed from standard technique sample targets in 90/91 cases. More Ktrans-based than standard imaging-based samples could be extracted. Diagnoses from Ktrans-based samples were more frequently concordant with the reference gross tumor diagnoses than those from standard imaging-based samples (WHO IV: 30/39 vs. 11/20; pu2009=u20090.08; WHO III/II: 12/13 vs. 6/11; pu2009=u20090.06). In 4/5 non-contrast-enhancing gliomas, Ktrans-based selection revealed significantly more accurate samples than standard technique sample-selection (10/12 vs. 2/8 samples; pu2009=u20090.02). If Ktrans elevation is present, Ktrans-based biopsy targeting provides significantly more diagnostic tissue samples in non-contrast-enhancing glioma than selection based on CET1W and FLAIR-weighted images alone.

Intravoxel incoherent motion MRI in the brain: Impact of the fitting model on perfusion fraction and lesion differentiability

To investigate the effect of the choice of the curve‐fitting model on the perfusion fraction (fIVIM) with regard to tissue type characterization, correlation with microvascular anatomy, and dynamic contrast‐enhanced magnetic resonance imaging (DCE‐MRI) parameters. Several curve‐fitting models coexist in intravoxel incoherent motion (IVIM) MRI to derive the (fIVIM).

Effects of arterial input function selection on kinetic parameters in brain dynamic contrast-enhanced MRI

PURPOSEnKinetic parameters derived from dynamic contrast-enhanced MRI (DCE-MRI) were suggested as a possible instrument for multi-parametric lesion characterization, but have not found their way into clinical practice yet due to inconsistent results. The quantification is heavily influenced by the definition of an appropriate arterial input functions (AIF). Regarding brain tumor DCE-MRI, there are currently several co-existing methods to determine the AIF frequently including different brain vessels as sources. This study quantitatively and qualitatively analyzes the impact of AIF source selection on kinetic parameters derived from commonly selected AIF source vessels compared to a population-based AIF model.nnnMATERIAL AND METHODSn74 patients with brain lesions underwent 3D DCE-MRI. Kinetic parameters [transfer constants of contrast agent efflux and reflux Ktrans and kep and, their ratio, ve, that is used to measure extravascular-extracellular volume fraction and plasma volume fraction vp] were determined using extended Tofts model in 821 ROI from 4 AIF sources [the internal carotid artery (ICA), the closest artery to the lesion, the superior sagittal sinus (SSS), the population-based Parker model]. The effect of AIF source alteration on kinetic parameters was evaluated by tissue type selective intra-class correlation (ICC) and capacity to differentiate gliomas by WHO grade [area under the curve analysis (AUC)].nnnRESULTSnArterial AIF more often led to implausible ve >100% values (p<0.0001). AIF source alteration rendered different absolute kinetic parameters (p<0.0001), except for kep. ICC between kinetic parameters of different AIF sources and tissues were variable (0.08-0.87) and only consistent >0.5 between arterial AIF derived kinetic parameters. Differentiation between WHO III and II glioma was exclusively possible with vp derived from an AIF in the SSS (p=0.03; AUC 0.74).nnnCONCLUSIONnThe AIF source has a significant impact on absolute kinetic parameters in DCE-MRI, which limits the comparability of kinetic parameters derived from different AIF sources. The effect is also tissue-dependent. The SSS appears to be the best choice for AIF source vessel selection in brain tumor DCE-MRI as it exclusively allowed for WHO grades II/III and III/IV glioma distinction (by vp) and showed the least number of implausible ve values.

Meningioma assessment: Kinetic parameters in dynamic contrast-enhanced MRI appear independent from microvascular anatomy and VEGF expression

BACKGROUND AND PURPOSEnKinetic parameters of T1-weighted dynamic contrast-enhanced magnetic resonance imaging (DCE-MRI) are considered to be influenced by microvessel environment. This study was performed to explore the extent of this association for meningiomas.nnnMATERIALS AND METHODSnDCE-MRI kinetic parameters (contrast agent transfer constants Ktrans and kep, volume fractions vp and ve) were determined in pre-operative 3T MRI of meningioma patients for later biopsy sites (19 patients; 15 WHO Io, no previous radiation, and 4 WHO IIIo pre-radiated recurrent tumors). Sixty-three navigated biopsies were consecutively retrieved. Biopsies were immunohistochemically investigated with endothelial marker CD34 and VEGF antibodies, stratified in a total of 4383 analysis units and computationally assessed for VEGF expression and vascular parameters (vessel density, vessel quantity, vascular fraction within tissue [vascular area ratio], vessel wall thickness). Derivability of kinetic parameters from VEGF expression or microvascularization was determined by mixed linear regression analysis. Tissue kinetic and microvascular parameters were tested for their capacity to identify the radiation status in a subanalysis.nnnRESULTSnKinetic parameters were neither significantly related to the corresponding microvascular parameters nor to tissue VEGF expression. There was no significant association between microvessel density and its presumed correlate vp (P=0.07). The subgroup analysis of high-grade radiated meningiomas showed a significantly reduced microvascular density (AUC 0.91; P<0.0001) and smaller total vascular fraction (AUC 0.73; P=0.01).nnnCONCLUSIONSnIn meningioma, DCE-MRI kinetic parameters neither allow for a reliable prediction of tumor microvascularization, nor for a prediction of VEGF expression. Kinetic parameters seem to be determined from different independent factors.

New prognostic factor telomerase reverse transcriptase promotor mutation presents without MR imaging biomarkers in primary glioblastoma

PurposeMagnetic resonance (MR) imaging biomarkers can assist in the non-invasive assessment of the genetic status in glioblastomas (GBMs). Telomerase reverse transcriptase (TERT) promoter mutations are associated with a negative prognosis. This study was performed to identify MR imaging biomarkers to forecast the TERT mutation status.MethodsPre-operative MRIs of 64/67 genetically confirmed primary GBM patients (51/67 TERT-mutated with rs2853669 polymorphism) were analyzed according to Visually AcceSAble Rembrandt Images (VASARI) (https://wiki.cancerimagingarchive.net/display/Public/VASARI+Research+Project) imaging criteria by three radiological raters. TERT mutation and O6-methylguanine-DNA methyltransferase (MGMT) hypermethylation data were obtained through direct and pyrosequencing as described in a previous study. Clinical data were derived from a prospectively maintained electronic database. Associations of potential imaging biomarkers and genetic status were assessed by Fisher and Mann-Whitney U tests and stepwise linear regression.ResultsNo imaging biomarkers could be identified to predict TERT mutational status (alone or in conjunction with TERT promoter polymorphism rs2853669 AA-allele). TERT promoter mutations were more common in patients with tumor-associated seizures as first symptom (26/30 vs. 25/37, pxa0=xa00.07); these showed significantly smaller tumors [13.1 (9.0–19.0) vs. 24.0 (16.6–37.5) all cm3; pxa0=xa00.007] and prolonged median overall survival [17.0 (11.5–28.0) vs. 9.0 (4.0–12.0) all months; pxa0=xa00.02]. TERT-mutated GBMs were underrepresented in the extended angularis region (pxa0=xa00.03), whereas MGMT-methylated GBMs were overrepresented in the corpus callosum (pxa0=xa00.03) and underrepresented temporomesially (pxa0=xa00.01).ConclusionImaging biomarkers for prediction of TERT mutation status remain weak and cannot be derived from the VASARI protocol. Tumor-associated seizures are less common in TERT mutated glioblastomas.

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.