Unloader bracing in osteoarthritis of the knee - Is there a direct effect on the damaged cartilage?

BACKGROUND: Unloading knee braces represent a conservative treatment option for non-pharmalogical management of unicompartmental osteoarthritis of the knee. Though there is consensus on the clinical effectiveness of unloading, the effect mechanism of bracing remains part of a debate. Our study was designed to assess the effect of unloader bracing on damaged cartilage via MRI cartilage mappings. METHODS: Fourteen patients (7 female, 7 male, mean age 43.1 ± 9.4 years) with unicompartmental cartilage wear in knees with varus or valgus malalignment were enrolled. Clinical scores, radiographs and MR-graphic properties (T2/T2* mapping, T1 Delayed Gadolinium Enhanced MRI of the cartilage (dGEMRIC) mapping, high-resolution PDw sequences) of knee cartilage were recorded before and three months after brace use. RESULTS: Bracing the knees for a mean of 14.4 ± 2.0 weeks (range 11 to 18 weeks) resulted in significant pain reduction (VAS changed from 5.9 ± 2.0 to 2.0 ± 1.3, p < 0.001) and improvement in knee function (KOOS increased from 42.1 ± 22.7 to 64.8 ± 18.7, p < 0.001). In the affected cartilage regions T2 relaxation times significantly decreased from 56.1 ± 11.4 ms to 46.5 ± 11.2 ms (p < 0.05). No changes in T1-dGEMRIC and T2* relaxation times, thickness or the extent of the damaged cartilage area could be detected. CONCLUSIONS: Our results suggest, that unloader bracing improves the biochemical properties of the damaged cartilage by increasing collagen and proteoglycan concentration as well as decreasing the cartilage edema.

Abdominal ultrasound in head and neck squamous cell carcinoma staging: yes or no?

PURPOSE: Abdominal ultrasound is a diagnostic staging procedure for distant metastases in head and neck squamous cell carcinoma (HNSCC). However, currently performed abdominal staging procedures do not follow consistent standards. Therefore, this retrospective study on 498 patients aimed at investigating on abdominal ultrasound as a staging procedure in HNSCC. MATERIALS AND METHODS: A retrospective analysis of 498 head and neck cancer patients treated in our Department of Head and Neck Surgery between 2008 and 2015 was performed. Disease-related data were collected over a mean follow-up time of 30.3 months, and results of abdominal ultrasound were analyzed. RESULTS: 426 patients received abdominal ultrasound as a staging procedure. 7% (29) were suspicious for metastases. In 19 cases (66%), the detected abnormalities were masses of the liver. In four patients, abdominal metastases were confirmed at the time of initial diagnosis. 16 patients developed abdominal metastases in the course of the disease (on average 623 days after initial diagnosis). 19 out of 20 patients with abdominal metastases had an N2/N3 cervical lymph node status. In this study, the negative predictive value of abdominal ultrasound for HNSCC staging was 99.03%, while the positive predictive value yielded 5.88% (N2/N3-patients). CONCLUSION: Only in patients with locally advanced lymph-node-status (N2/N3), abdominal ultrasound can be useful as a staging investigation to exclude abdominal metastasis in HNSCC patients. For N0/N1 patients, abdominal ultrasound might be dispensed. Of note, in case of a positive result, further diagnostic procedures are mandatory.

Multimodal therapy of recurrent and refractory bleeding from esophageal varices - case report and review of the literature.

Bleeding from esophageal varices is a major cause of mortality in patients with advanced liver disease. Although standard treatment and secondary prophylaxis are effective, in some patients sustained hemostasis cannot be achieved. We report the case of a woman with alcoholic liver disease in whom pharmacological, endoscopic, and intravascular therapies failed to control variceal bleeding. Only a combination of (repeated) band ligation, insertion of a self-expanding metal stent, TIPS implantation and redilatation, transjugular variceal embolization, and finally implantation of a portocaval shunt proved to be successful. We discuss the stepwise approach to this situation and the challenges encountered in the process.

Hip imaging of avascular necrosis at 7 Tesla compared with 3 Tesla.

OBJECTIVES: To compare ultra-high field, high-resolution bilateral magnetic resonance imaging (MRI) of the hips at 7 Tesla (T) with 3 T MRI in patients with avascular necrosis (AVN) of the femoral head by subjective image evaluations, contrast measurements, and evaluation of the appearance of imaging abnormalities. MATERIALS AND METHODS: Thirteen subjects with avascular necrosis treated using advanced core decompression underwent MRI at both 7 T and 3 T. Sequence parameters as well as resolution were kept identical for both field strengths. All MR images (MEDIC, DESS, PD/T2w TSE, T1w TSE, and STIR) were evaluated by two radiologists with regard to subjective image quality, soft tissue contrasts, B1 homogeneity (four-point scale, higher values indicating better image quality) and depiction of imaging abnormalities of the femoral heads (three-point scale, higher values indicating the superiority of 7 T). Contrast ratios of soft tissues were calculated and compared with subjective data. RESULTS: 7-T imaging of the femoral joints, as well as 3-T imaging, achieved "good" to "very good" quality in all sequences. 7 T showed significantly higher soft tissue contrasts for T2w and MEDIC compared with 3 T (cartilage/fluid: 2.9 vs 2.2 and 3.6 vs 2.6), better detailed resolution for cartilage defects (PDw, T2w, T1w, MEDIC, DESS > 2.5) and better visibility of joint effusions (MEDIC 2.6; PDw/T2w 2.4; DESS 2.2). Image homogeneity compared with 3 T (3.9-4.0 for all sequences) was degraded, especially in TSE sequences at 7 T through signal variations (7 T: 2.1-2.9); to a lesser extent also GRE sequences (7 T: 2.9-3.5). Imaging findings related to untreated or treated AVN were better delineated at 3 T (≤1.8), while joint effusions (2.2-2.6) and cartilage defects (2.5-3.0) were better visualized at 7 T. STIR performed much more poorly at 7 T, generating large contrast variations (1.5). CONCLUSIONS: 7-T hip MRI showed comparable results in hip joint imaging compared with 3 T with slight advantages in contrast detail (cartilage defects) and fluid detection at 7 T when accepting image degradation medially.

Hepatic volume changes after lobar selective internal radiation therapy (SIRT) of hepatocellular carcinoma.

AIM: To assess volume changes of treated and non-treated liver segments after selective internal radiation therapy (SIRT) in patients with hepatocellular carcinoma (HCC) and compromised hepatic function due to cirrhosis over a time course of 12 months after SIRT. MATERIALS AND METHODS: All patients underwent SIRT of the right liver lobe with yttrium 90 (Y-90). Absolute volumes of the right liver lobe (RLV) and left liver lobe (LLV) were assessed using computed tomography (CT) before and 1, 3, 6, 9, and 12 months after SIRT. Changes at follow-up relative to baseline volumes were analysed ("normalized" volumes). Furthermore, the relative volume of the LLV [LLV/(RLV + LLV)] was calculated ("relative" volumes). For statistical analysis p < 0.05 was considered statistically significant. RESULTS: Forty-five HCC patients (36 men, nine women, mean age 71.9 years, range 55-90 years) were studied. The mean baseline RLV and LLV reached 1116 ml [95% confidence intervals (CI): 1006-1226 ml] and 601 ml (95% CI: 514-688 ml), respectively. At 6 months following radioembolization, the LLV increased by 30.8% (RLV -33.9%), with the relative LLV increasing from 35% (pre-radioembolization) to 50.5%. RLV further decreased and LLV increased 12 months after SIRT (nRLV -44.9%, nLLV +40.1%, relative LLV 56.5%). All changes were significant. CONCLUSION: Constraints of liver function after radioembolization of one liver lobe can be partially compensated through hypertrophy of the contralateral lobe. The rate of volumetric changes is the highest in the first 6 months following radioembolization. The present data can also be the basis to propagate radiation lobectomy for selected patients, simultaneously providing tumour control and future remnant liver hypertrophy before curative hemihepatectomy.

Bilateral hip imaging at 7 Tesla using a multi-channel transmit technology: initial results presenting anatomical detail in healthy volunteers and pathological changes in patients with avascular necrosis of the femoral head.

OBJECTIVE: To evaluate 7-T MRI of both hips using a multi-channel transmit technology to compensate for inherent B1 inhomogeneities in volunteers and patients with avascular necrosis of the femoral head. MATERIALS AND METHODS: A self-built, eight-channel transmit-receive coil was utilized for B1 modification at 7 T. Two shim modes (individual shim vs. CP2+ mode) were initially compared and the best shim result was used for all further imaging. Robustness of sequences against B1 inhomogeneities, appearance of anatomic and pathologic changes of the femoral heads of MEDIC, DESS, PD/T2w TSE, T1w TSE, and STIR sequences at 7 T were evaluated in 12 subjects on a four-point scale (1-4): four male volunteers and eight patients (seven males, one female) suffering from avascular necrosis treated by advanced core decompression. RESULTS: Successful MRI of both femoral heads was achieved in all 12 subjects. CP2+ mode proved superior in ten of 12 cases. DESS proved most robust against B1 inhomogeneity. Anatomical details (labrum, articular cartilage) were best depicted in PDw, MEDIC, and DESS, while for depiction of pathological changes PDw, DESS (0.76 mm(3)) and T1w were superior. CONCLUSIONS: Our initial results of ultra-high-field hip joint imaging demonstrate high-resolution, high-contrast images with a good depiction of anatomic and pathologic changes. However, shifting areas of signal dropout from the femoral heads to the center of the pelvis makes these areas not assessable. For clinical workflow CP2+ mode is most practical. Seven-Tesla MRI of the hip joints may become a valuable complement to clinical field strengths.

MRI of the ankle joint in healthy non-athletes and in marathon runners: image quality issues at 7.0 T compared to 1.5 T.

OBJECTIVE: To present imaging characteristics of the ankle at 7.0 T and to investigate the appearance and image quality of presumed pathologies of ankles without physical strain as well as of ankles after a marathon run in comparison to 1.5 T. MATERIALS AND METHODS: Appearance of presumed pathologic findings and image quality of TSE (PD, T2, and STIR) and GRE sequences (MEDIC, DESS, and/or CISS) at 7.0 T and 1.5 T MRI were compared by two senior radiologists in consensus in two healthy controls without strain and in six marathon runners after a full-length marathon (eight males, mean age 49.1 years). RESULTS: Overall, 7.0 T MRI allowed for higher resolution images for most of the sequences while requiring comparable acquisition times and achieving high contrast images mainly in gradient echo sequences. Bursal or presumed peritendineal fluid and/or edematous tissue, which were found in seven of eight subjects, could be best appreciated with 7.0 T MEDIC. Other findings with sharper delineation at 7.0 T included cartilage defects (best: CISS), osseous avulsions, and osteophytes (best: DESS). Nevertheless, 1.5 T STIR imaging enabled assessment of a tibiotalar bone edema-like lesion in two runners, which was barely visible at 7.0 T using STIR, but not with any other sequence at 7.0 T including MEDIC (with frequency selective fat suppression). 7.0 T showed larger image quality variations with challenges especially in the TSE sequences. CONCLUSION: Our initial results of ultra-high-field ankle joint imaging demonstrate the improved depiction of ankle anatomy, fluid depositions, and cartilage defects. However imaging of edema-like bone lesions remains challenging at ultra-high magnetic field strength, and TSE coverage in particular is limited by the specific absorption rate.

Imaging of brain metastases of bronchial carcinomas with 7 T MRI - initial results.

PURPOSE: To compare the depiction of brain metastases of bronchial carcinomas on susceptibility-weighted and contrast-enhanced images with 7 T and at 1.5 T MRI. MATERIALS AND METHODS: Twelve patients with brain metastases of bronchial carcinomas underwent 7 T and 1.5 T MRI. Minimum intensity projections (MinIP) of a 1.5 T SWI sequence (voxel size = 0.9 x 0.9 x 2.0 mm(3)) were compared to 7 T SWI MinIPs (voxel size = 0.4 x 0.4 x 1.5 mm(3)). A T 1-w 3D MPRAGE at 1.5 T (voxel size = 1 x 1 x 1 mm(3) after double-dose (DD) gadoterate meglumine, Gd-DOTA) was compared to a 7 T MPRAGE sequence (voxel size = 0.7 x 0.7 x x 0.7 mm(3), single dose (SD) Gd-DOTA) in all patients, and to DD Gd-DOTA in 6 patients after a 10 minute delay. The number of intracranial microhemorrhages in SWI MinIPs and the number of contrast-enhancing metastases in MPRAGE images were compared in each patient grouped into three size ranges (< or = 2 mm, > 2 mm and < 6 mm, > or = 6 mm) by two radiologists in consensus. RESULTS: In all 12 patients the 7 T SWI with spatially higher resolution allowed the identification of 87 versus 67 cerebral microhemorrhages at 1.5 T. 7 T T 1-w images after SD Gd-DOTA depicted 198 brain metastases versus 238 at 1.5 T after DD Gd-DOTA. After doubling the contrast dose in six patients, 4 additional brain metastases were identified at 7 T. CONCLUSION: Our preliminary results indicate that despite the higher spatial resolution the detection of brain metastases on 7 T MPRAGE images is almost equal to 1.5 T MPRAGE images. The 7 T SWI sequence with spatially higher resolution allowed the detection of 20 % more microhemorrhages in brain metastases compared to the 1.5 T SWI sequence.

First clinical study on ultra-high-field MR imaging in patients with multiple sclerosis: comparison of 1.5T and 7T.

BACKGROUND AND PURPOSE: Higher magnetic field strengths and continuous improvement of high-resolution imaging in multiple sclerosis (MS) are expected to provide unique in-vivo and non-invasive insights in pathogenesis and clinical monitoring. The purpose of this study was to investigate the potential of high-resolution imaging of MS lesions in vivo comparing 7T with conventional 1.5T. MATERIALS AND METHODS: Twelve consecutive patients with clinically definite MS were scanned on a 7T whole-body scanner and on a 1.5T Avanto. The 1.5T and 7T imaging protocol consisted of high-resolution axial proton density (PD) + T2-weighted turbo spin-echo and T2*-weighted gradient-echo (GRE), and sagittal T1-weighted 3D magnetization-prepared rapid acquisition of gradient echo. RESULTS: The sequence parameters at 7T had to be modified because of specific absorption rate (SAR) restrictions while keeping contrast parameters equivalent to 1.5T. White matter lesions were better detected and delineated from adjacent structures at 7T compared with 1.5T. There were 42% of the patients who showed additional lesions at 7T: there were 97 white matter lesions detected on 1.5T versus 126 lesions at 7T, an increase of 23%. The perivascular migration of MS lesions was well visualized on T2*-weighted GRE sequences. In larger lesions (10 mm), a multilayer structure was revealed on T2*-weighted GRE not seen at 1.5T. Because of the higher resolution, it was possible to differentiate between juxtacortical white matter lesions and cortical lesions. There were 44% of the subcortical lesions depicted at 7T that showed cortical involvement. CONCLUSIONS: Ultra-high-field imaging of patients with MS at 7T was well tolerated and provided better visualization of MS lesions in the gray matter and demonstrated structural abnormalities within the MS lesions themselves more effectively.

Evaluation of intracranial aneurysms with 7 T versus 1.5 T time-of-flight MR angiography - initial experience.

PURPOSE: The purpose of this study was to compare the depiction of intracranial aneurysms by 3D time-of-flight (TOF) magnetic resonance angiography (MRA) at 7 Tesla (T) with the clinical standard TOF MRA at 1.5 T and with digital subtraction angiography (DSA). MATERIALS AND METHODS: 7 T and 1.5 T TOF MRA images optimized for both field strengths were compared in ten patients with an unruptured intracranial aneurysm. Two blinded neuroradiologists independently rated the image quality of the dome, the neck, and the vessel of origin of all aneurysms in MRA source and maximum intensity projection (MIP) images. DSA was obtained in all subjects and served as reference standard. The mean values of image quality were compared by Wilcoxon signed rank test. In all patients the number and location of the aneurysms was confirmed by DSA. RESULTS: Both readers identified twelve aneurysms in ten patients in 7 T, 1.5 T TOF MRA and DSA. The image quality of the aneurysm dome was rated higher in 8 of 12 aneurysms and the image quality of the aneurysm neck was superior in 9 of 12 aneurysms at 7 T TOF MRA compared to 1.5 T TOF MRA. The depiction of the parent vessel was graded almost equally by both readers. CONCLUSION: Our initial results indicate that image quality of intracranial aneurysms may benefit from the increased spatial resolution of 7 T TOF MRA compared with 1.5 T TOF MRA. Tailored scan protocols and optimized radiofrequency head coils are needed to further improve the image quality of 7 T TOF MRA.

MRI of the knee at 7.0 Tesla.

PURPOSE: Measurement protocols which have been optimized for MRI at field strengths of 1.5 T or 3 T cannot be directly transferred to 7 T. Specific absorption rate limitations, different tissue relaxation times, as well as new image artifacts require adjustments of the sequence parameters. The goal of our study was to investigate and optimize various sequences for 7 T imaging of the knee. MATERIALS AND METHODS: Starting with sequences used on a standard 1.5 T scanner, the parameters were modified to obtain optimal image contrast, maximum coverage, and the highest spatial resolution within a reasonable acquisition time. All sequences were optimized in two healthy volunteers and then tested in 10 patients with various pathologies. High-resolution 7 T images with several SE and GRE sequences were acquired and compared to 1.5 T images. RESULTS: A comparison of 1.5 T and 7 T images clearly shows the advantage of MRI at higher field strengths, especially the higher SNR which could be translated into higher spatial resolution. The MEDIC sequence appears to be very well suited for the assessment of cartilage pathologies at 7 T. Using the DESS sequence, full coverage of the knee can be obtained with a very high resolution of 0.4 x 0.4 x 1.0 mm(3) within 7 minutes. Despite optimization of the STIR sequence parameters, bone marrow edema is better visualized at 1.5 T compared to 7 T. The PD TSE renders excellent image quality at 7 T. The total acquisition time of the 7 T protocol is approximately 40 minutes. CONCLUSION: Gradient echo sequences provide excellent image contrast at very high spatial resolution in a reasonable scan time. However, not all sequences used at 1.5 T are currently well suited for high-field imaging, in particular SAR-intensive sequences. Imaging of meniscal tears and lesions of the cruciate ligaments may benefit from the higher spatial resolution. The most favorable clinical indication for knee examinations at 7 T currently appears to be cartilage imaging.