Three-Dimensional Isotropic Fat-Suppressed Proton Density-Weighted MRI at 3 Tesla Using a T/R-Coil Can Replace Multiple Plane Two-Dimensional Sequences in Knee Imaging.

PURPOSE: To evaluate whether a 3 D proton density-weighted fat-suppressed sequence (PDwFS) of the knee is able to replace multiplanar 2D-PDwFS. MATERIALS AND METHODS: 52 patients (26 men, mean age: 41.9 ±â€Š14.5years) underwent magnetic resonance imaging (MRI) of the knee at 3.0 Tesla using a T/R-coil. The imaging protocol included 3 planes of 2D-PDwFS (acquisition time (AT): 6:40 min; voxel sizes: 0.40 - 0.63 × 0.44 - 0.89 × 3mm³) and a 3D-PDwFS (AT: 6:31 min; voxel size: 0.63 × 0.68 × 0.63mm³). Homogeneity of fat suppression (HFS), artifacts, and image sharpness (IS) were evaluated on a 5-point scale (5[excellent] - 1[non-diagnostic]). The sum served as a measure for the overall image quality (OIQ). Contrast ratios (CR) compared to popliteal muscle were calculated for the meniscus (MEN), anterior (ACL) and posterior cruciate ligaments (PCL). In 13 patients who underwent arthroscopic knee surgery, two radiologists evaluated the presence of meniscal, ligamental and cartilage lesions to estimate the sensitivity and specificity of lesion detection. RESULTS: The CR was higher in the ACL, PCL and MEN in 3D- PDwFS compared to 2D-PDwFS (p < 0.01 for ACL and PCL; p = 0.07 for MEN). Compared to 2 D images, the OIQ was rated higher in 3D-PDwFS images (p < 0.01) due to fewer artifacts and HFS despite the lower IS (p < 0.01). The sensitivity and specificity of lesion detection in 3D- and 2D-PDwFS were similar. CONCLUSION: Compared to standard multiplanar 2D-PDwFS knee imaging, isotropic high spatial resolution 3D-PDwFS of the knee at 3.0 T can be acquired with high image quality in a reasonable scan time. Multiplanar reformations in arbitrary planes may serve as an additional benefit of 3D-PDwFS. KEY POINTS: • 3D-PDwFS of the knee is acquired with high image quality• 3D-PDwFS can be achieved in only one measurement with a reasonable scan time• 3D-PDwFS with the advantage of multiplanar reformation may replace 2D-PD-weighted knee MRI Citation Format: • Homsi R, Gieseke J, Luetkens JA et al. Three-Dimensional Isotropic Fat-Suppressed Proton Density-Weighted MRI at 3 Tesla Using a T/R-Coil Can Replace Multiple Plane Two-Dimensional Sequences in Knee Imaging. Fortschr Röntgenstr 2016; 188: 949 - 956.

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

UNLABELLED: Alcohol 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 Wernicke's 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. KEY POINTS: Alcohol-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.

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-resolved" = TR-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. g. 4D-TRAK), TRICKS - both with and without projection - and HYPR-reconstruction, TREAT, and TWIST. Some of these techniques were first introduced in the 1980 s and 1990 s, 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.

Noninvasive evaluation of cerebral arteriovenous malformations by 4D-MRA for preoperative planning and postoperative follow-up in 56 patients: comparison with DSA and intraoperative findings.

BACKGROUND AND PURPOSE: 4D-MRA is a promising technique in the diagnosis and follow-up of cAVMs. The purpose of this study was to compare 4D-MRA in the pre- and postoperative evaluation of cAVMs with DSA or intraoperative findings as the standards of reference regarding qualitative and quantitative parameters. MATERIALS AND METHODS: Fifty-six consecutive patients with cAVMs (30 women) underwent both 4D-MRA and DSA. Preoperative 4D-MRA was excluded from analysis in 1 patient (movement artifacts). Twenty-five patients underwent surgery on cAVMs and underwent both imaging modalities pre- and postoperatively. 4D-MRA was performed with either 0.5-mol/L gadolinium-diethylene-triamine pentaacetic acid (group 1: voxel size, 1.1 × 1.1 × 1.4 mm(3); 608 ms/dynamic frame; 19 patients) or 1.0-mol/L gadobutrol (group 2: voxel size, 1.1 × 1.1 × 1.1 mm(3); 572 ms/dynamic frame; additional alternating view sharing; 37 patients). Two readers independently reviewed 4D-MRA and DSA regarding the Spetzler-Martin classification, arterial feeders, and postoperative residual filling. Vessel sharpness, vessel diameter, and VBC of 4D-MRA were quantified. RESULTS: Preoperative Spetzler-Martin classification 4D-MRA and DSA ratings matched in 55/55 patients (Spetzler-Martin grades: I, 12; II, 22; III, 15; IV, 5; V, 1), and 93/100 arterial feeders were correctly identified by preoperative 4D-MRA (7 additional arterial feeders identified by DSA only: group 1, 3/19; group 2, 4/36). Postoperative 4D-MRA and DSA matched in 25/25 patients (residual filling, 1/25). Vessel sharpness and diameters did not differ substantially between the 2 groups. VBC was significantly higher in group 2 (P < .005). CONCLUSIONS: 4D-MRA is a reliable tool that allows predicting Spetzler-Martin classification and postoperative residual filling; it hence allows substituting DSA in the pre- and postoperative evaluation of patients with cerebral AVMs.

Mechanical thrombectomy compared to local-intraarterial thrombolysis in carotid T and middle cerebral artery occlusions: a single center experience.

PURPOSE: The aim of the study was to examine the effects of mechanical thrombectomy using the Solitaire stent in patients with thromboembolic occlusions of the intracranial carotid artery bifurcation (carotid T) or middle cerebral artery (MCA) and to compare the results with a historical cohort treated with local intraarterial thrombolysis using urokinase. METHODS: The time intervals from stroke onset to treatment, recanalization rates, occlusion sites, recanalization times and functional outcomes on the modified Rankin scale at 3 months in 25 patients treated with the Solitaire stent between 2010 and 2011 were evaluated. The data were compared with those of a historical cohort of 62 patients treated with local intraarterial thrombolysis between 1992 and 2001. RESULTS: A total of 15 out of 25 (60%) patients treated with mechanical thrombectomy and 25 out of 62 (40%) treated with local intraarterial thrombolysis achieved a modified Rankin score of ≤2 (p = 0.07). Occlusion sites, intervals from stroke onset to treatment and rates of parenchymal hematomas, 3 out of 25 (12%) versus 8 out of 62 (13%), were similar in both cohorts while the recanalization rate was significantly higher, 22 out of 25 (88%) versus 33 of 62 (53%), in the mechanical thrombectomy group (p ≤ 0.01). CONCLUSION: The data show that mechanical thrombectomy is superior to local intraarterial thrombolysis with respect to the recanalization rate in patients with thrombeoembolic carotid T or MCA occlusions.

Gated multidetector computed tomography. A technique to reduce intracranial aneurysm clip and coil artifacts.

BACKGROUND AND PURPOSE: Streak artifacts caused by aneurysm clips and coils impede image quality in multidetector computed tomography (MDCT). The authors propose a technique to minimize these artifacts by gated data reconstruction and shifting the reconstruction window. PATIENTS AND METHODS: Intracranial CT angiograms were acquired in the follow-up of six patients with clipped and coiled intracranial aneurysms, respectively. Images were reconstructed from four consecutive 45 degrees rotated segments with an acquisition time of 52.5 ms/segment. Data acquisition was gated via an external pacemaker cable-connected to the scanner. RESULTS: Artifact orientation could be rotated by shifting the reconstruction window and interesting vessel segments visualized without disturbing streak artifacts. This allowed to assess the posterior communicating artery origin in two cases and a middle cerebral artery aneurysm remnant in another case, respectively. However, due to a higher noise interesting vessel segments were not adjustable in another three patients. CONCLUSION: Gated MDCT is a promising technique to reduce the amount and to change the position of artifacts induced by clips or coils.

Postsurgical intracranial hypotension: diagnostic and prognostic imaging findings.

BACKGROUND AND PURPOSE: CSF loss with consecutive intracranial hypotension has been discussed as a possible pathogenetic mechanism in poor clinical outcome after uneventful neurosurgery and appears to be correlated to specific imaging findings. The purpose of this study was to describe the clinical and imaging findings of symptomatic intracranial hypotension likely induced by wound suction drainage. MATERIALS AND METHODS: This is a review of previously published cases of patients in whom this condition developed after uneventful intracranial surgery. We performed an analysis of 3 more cases, of which 2 occurred after spinal surgery with accidental dural opening. RESULTS: Sixteen patients who remained unconscious or did not become fully responsive after surgery showed symmetric bilateral thalamic/basal ganglia signal intensity changes on CT and MR imaging studies. Of these 16 patients, 4 died and 2 also had brain stem signal intensity changes. All patients had rapid and distinct intraoperative and postoperative CSF loss documented on CT and/or MR imaging studies by a transient increase of the sag ratio, defined as maximal anteroposterior midbrain diameter by maximal bipeduncular diameter. CONCLUSIONS: The clinical course and typical MR imaging findings characterize the disease entity postsurgical intracranial hypotension. These findings also underline the potential danger of wound suction drainage in the case of possible CSF loss.

[Pediatric renal cell carcinoma. A rare differential diagnosis of Wilms' tumor]. / Das Nierenzellkarzinom beim Kind. Eine seltene Differenzialdiagnose zum Wilms-Tumor.

Renal cell carcinoma (RCC) is a very rare pediatric disease and should be treated as an entity of its own because of differences in symptoms, therapy, and prognosis from the adult form of the disease. Our objective is to discuss the difficulties in clinical diagnosis, prognosis, and therapy of this very rare disease in children and to provide a review of the current literature.

Magnetic resonance (MR) imaging and MR angiography for evaluation and follow-up of hepatic artery banding in patients with hepatic involvement of hereditary hemorrhagic telangiectasia.

BACKGROUND: We describe findings obtained by magnetic resonance angiography (MRA) and magnetic resonance imaging (MRI) for evaluation and follow-up after hepatic artery banding in patients with hepatic involvement of hereditary hemorrhagic telangiectasia (HHT). METHODS: Abdominal MRA and liver MRI were performed in three patients with HHT as clinically defined by Curacao criteria. One patient underwent MRA and MRI twice for preinterventional evaluation and follow-up, one patient for preinterventional evaluation, and one patient for postinterventional evaluation. Hepatic vascular involvement of the disease and postinterventional vascular anatomy were evaluated by two radiologists by consensus. RESULTS: Hepatic vascular involvement with perfusion disorders and arteriosystemic shunts was found in all three patients. MRA and MRI allowed diagnostic characterization of hepatic vascular disease (three of three), preinterventional evaluation of complex vascular anatomy and variants (two of two), and postinterventional follow-up of hepatic artery banding (two of two). CONCLUSION: In preinterventional evaluation and postinterventional follow-up, MRA and MRI allows characterization of complex hepatic vascular alterations of HHT and, hence, is an alternative to other imaging modalities in the diagnosis, clinical decision making, and follow-up of HHT.

[Contrast-enhanced "low MI real-time" sonography for the assessment of the malignancy of focal liver lesions]. / Kontrastmittelgestützte "Low-MI-Real-Time"-Sonographie zur Beurteilung der Dignität fokaler Leberläsionen.

PURPOSE: Contrast enhanced sonography using phase-inversion harmonic mode is a promising technique to detect and characterize hepatic lesions. Aim of the following study was to evaluate whether this technique can characterize liver tumors. MATERIAL AND METHODS: During January and December 2004, 46 patients with a solitary liver lesion were examined. The age of the 21 women and 25 men ranged between 37 and 82 years. The tumor size was between 8 mm and 14.5 cm. First conventional B-mode sonography and color-coded sonography were performed, followed by intravenous injection of the contrast agent SonoVue and continuous sonographic examination over 5 minutes using "low MI real-time" phase-inversion mode. The examination was video taped. The enhancement was evaluated qualitatively. RESULTS: Of the 21 malignant lesions, 20 could be correctly diagnosed as malignant. One of the malignant lesions was classified as benign. Of the 25 benign lesions, 21 could be classified correctly as benign, however, 4 lesions (2 hemangiomas, 1 adenoma, 1 teratoma) showed no enhancement in the portal and late phase and were incorrectly classified as malignant as well. CONCLUSION: Using pulse-inversion harmonic US with SonoVue, liver lesions showing an isoechoic or hyperechoic enhancement can be classified as probably benign. Further work up is necessary in case of little or no enhancement on delayed phase imaging.

[Pitfalls in contrast-enhanced liver sonography: consequences for the practice]. / Pitfalls in der kontrastverstärkten Lebersonographie: Konsequenzen für die Praxis.

Contrast-enhanced sonography performed as phase inversion harmonic imaging is a promising new technique for detection and characterization of hepatic foci. It has been reported that malignant liver tumors can be differentiated from benign entities with almost 100% sensitivity and that diagnosis of the type is possible with an accuracy of over 90%. The following report describes seven of our own cases and then compares the results we obtained with current knowledge, followed by a discussion. In summary, most hepatic lesions can be correctly characterized by supplemental use of enhanced sonography; practitioners should nevertheless be aware of atypical phenomena to be able to critically evaluate the findings.

Sensitivity encoding (SENSE) for high spatial resolution time-of-flight MR angiography of the intracranial arteries at 3.0 T.

PURPOSE: 1) To evaluate feasibility of sensitivity encoding (SENSE) for high spatial resolution intracranial 3D time-of-flight (TOF) MR angiography at 3.0 T using a 1024 imaging matrix and 2) to compare image quality and diagnostic yield with 3.0 T TOF MRA without SENSE. METHODS: In a prospective study TOF MR angiography of the circle of Willis was performed with SENSE in 24 patients on a clinical whole body 3.0 T MR system (Intera, Philips Medical Systems, NL). In the SENSE protocol (S-MRA), a SENSE factor of 2.5 was used to shorten acquisition time and to increase the anatomic coverage (5:12 min.; 150 slices). A matrix of 832 x 572 was acquired and reconstructed to 1024 yielding a non-zerofilled voxel size of 0.30 x 0.44 x 1.00 mm(3) (0.13 mm(3)). Two readers were asked to review the images regarding the presence of vascular disease, and to rate, in consensus, the quality of the angiograms on a 5-point scale (5 = excellent through 1 = non-diagnostic). Results were compared with the results in 15 subjects who underwent intracranial TOF MRA at 3.0 T without SENSE (NS-MRA: acquisition time, 7:57 min.; 100 slices). Digital subtraction angiography (DSA) served as standard of reference in the 4/24 patients in whom vascular disease was identified. RESULTS: S-MRA at 3.0 T was judged to provide image quality that was adequate for diagnosis or better in 24/24. Median score of image quality of S-MRA and NS-MRA were 5 and 5, respectively. In the 4 patients with DSA correlation, a total of 8 pathologic findings (7 steno-occlusive diseases, 1 aneurysm) were correctly identified on S-MRA. CONCLUSION: The use of SENSE for intracranial TOF MRA at very high imaging matrix is feasible at 3.0 T. Compared to the imaging technique without SENSE, it allows TOF MRA with substantially reduced acquisition time, and with substantially increased anatomic coverage while maintaining image quality of NS-MRA.