State-of-the-art aortic imaging: Part II - applications in transcatheter aortic valve replacement and endovascular aortic aneurysm repair.

Transcatheter aortic valve replacement (TAVR) as well as thoracic and abdominal endovascular aortic repair (TEVAR and EVAR) rely on accurate pre- and postprocedural imaging. This review article discusses the application of imaging, including preprocedural assessment and measurements as well as postprocedural imaging of complications. Furthermore, the exciting perspective of computational fluid dynamics (CFD) based on cross-sectional imaging is presented. TAVR is a minimally invasive alternative for treatment of aortic valve stenosis in patients with high age and multiple comorbidities who cannot undergo traditional open surgical repair. Given the lack of direct visualization during the procedure, pre- and peri-procedural imaging forms an essential part of the intervention. Computed tomography angiography (CTA) is the imaging modality of choice for preprocedural planning. Routine postprocedural follow-up is performed by echocardiography to confirm treatment success and detect complications. EVAR and TEVAR are minimally invasive alternatives to open surgical repair of aortic pathologies. CTA constitutes the preferred imaging modality for both preoperative planning and postoperative follow-up including detection of endoleaks. Magnetic resonance imaging is an excellent alternative to CT for postoperative follow-up, and is especially beneficial for younger patients given the lack of radiation. Ultrasound is applied in screening and postoperative follow-up of abdominal aortic aneurysms, but cross-sectional imaging is required once abnormalities are detected. Contrast-enhanced ultrasound may be as sensitive as CTA in detecting endoleaks.

State-of-the-art aortic imaging: part I - fundamentals and perspectives of CT and MRI.

Over the last two decades, imaging of the aorta has undergone a clinically relevant change. As part of the change non-invasive imaging techniques have replaced invasive intra-arterial digital subtraction angiography as the former imaging gold standard for aortic diseases. Computed tomography (CT) and magnetic resonance imaging (MRI) constitute the backbone of pre- and postoperative aortic imaging because they allow for imaging of the entire aorta and its branches. The first part of this review article describes the imaging principles of CT and MRI with regard to aortic disease, shows how both technologies can be applied in every day clinical practice, offering exciting perspectives. Recent CT scanner generations deliver excellent image quality with a high spatial and temporal resolution. Technical developments have resulted in CT scan performed within a few seconds for the entire aorta. Therefore, CT angiography (CTA) is the imaging technology of choice for evaluating acute aortic syndromes, for diagnosis of most aortic pathologies, preoperative planning and postoperative follow-up after endovascular aortic repair. However, radiation dose and the risk of contrast induced nephropathy are major downsides of CTA. Optimisation of scan protocols and contrast media administration can help to reduce the required radiation dose and contrast media. MR angiography (MRA) is an excellent alternative to CTA for both diagnosis of aortic pathologies and postoperative follow-up. The lack of radiation is particularly beneficial for younger patients. A potential side effect of gadolinium contrast agents is nephrogenic systemic fibrosis (NSF). In patients with high risk of NSF unenhanced MRA can be performed with both ECG- and breath-gating techniques. Additionally, MRI provides the possibility to visualise and measure both dynamic and flow information.

Detection and characterization of liver lesions using gadoxetic acid as a tissue-specific contrast agent.

The value of cross-sectional liver imaging is evaluated by the accuracy, sensitivity, and specificity of the specific imaging technique. Magnetic resonance imaging (MRI) has become a key technique for the characterization and detection of focal and diffuse liver disease. More recently, gadoxetic acid, the hepatocyte-specific MR contrast agent, was clinically approved and introduced in many countries. Gadoxetic acid may be considered a "molecular imaging" probe because the compound is actively taken into hepatocytes via the ATP-dependent organic anion transport system in the plasma membrane for the hepatic uptake. The transport of gadoxetic acid from the cytoplasm to the bile is mainly determined by the capacity of the transport protein glutathione-S-transferase. Gadoxetic acid enhances hepatocyte-containing lesions and improves detection of lesions devoid of normal hepatocytes, such as metastases. Innovative rapid MR acquisition techniques with near isotropic 3D pulse sequences with fat saturation parallel the technical progress made by multidetector computed tomography combined with an impressive improvement in tumor-liver contrast when used for gadoxetic acid-enhanced MRI. The purpose of this review is to provide an overview of the development, clinical testing, and applications of this novel MR contrast agent.

Arthroscopic supraspinatus tendon repair with suture-bridging technique: functional outcome and magnetic resonance imaging.

BACKGROUND: The suture-bridging technique is a new arthroscopic technique to repair rotator cuff tears. Biomechanical advantages compared with double-row fixations have been described. HYPOTHESIS: The authors hypothesized that arthroscopic suture-bridging repair of the supraspinatus tendon would result in a superior clinical outcome and lower retear rates compared with previously published results after double-row fixation. STUDY DESIGN: Case series; Level of evidence, 4. METHODS: Fifty-one consecutive patients, with a median age of 62 years (range, 37-76 years), who had undergone an arthroscopic suture-bridging repair of an isolated supraspinatus tendon tear were evaluated in this prospective study 4, 12, and a median of 24 months postoperatively. Subjective and functional outcome was assessed using the simple shoulder test and Constant score. With magnetic resonance imaging 12 months postoperatively, the tendon integrity and potential predictors of failures were evaluated. RESULTS: The simple shoulder test scores improved significantly from 9 points (range, 1-12 points) at 4 months, to 12 points (range, 1-12 points) at 12 months, and 12 points (range, 5-12 points) at 24 months postoperatively. The Constant score increased significantly from preoperative 64% (range, 37%-92%) to 82% (range, 36%-100%) at 4 months, 96% (range, 49%-100%) at 12 months, and 96% (range, 64%-100%) at 24 months postoperatively. Magnetic resonance imaging 12 months after surgery showed retears in 28.9%. Two different types of retears could be observed: insufficiently healed and medially retorn supraspinatus tendons. The Constant score did not differ significantly between the groups with retears and intact repairs. A patient age of more than 60 years was found to influence tendon healing significantly. CONCLUSION: The hypothesis, that arthroscopic suture-bridging repair of the supraspinatus tendon would result in a superior clinical outcome and lower retear rates compared with previously published results after double-row fixation, could not be confirmed. The functional outcome after the new suture-bridging technique was good and comparable with the reported results after double-row repair from the literature. A structural failure of tendon repair was not identical to clinical failure.

Additive fiber-cerclages in proximal humeral fractures stabilized by locking plates: no effect on fracture stabilization and rotator cuff function in human shoulder specimens.

BACKGROUND AND PURPOSE: The effect of additive fiber-cerclages in proximal humeral fractures stabilized by locking plates on fracture stabilization and rotator cuff function is unclear. Here it was assessed in a human cadaver study. METHODS: 24 paired human shoulder specimens were harvested from median 77-year-old (range 66-85) female donors. An unstable 3-part fracture model with an intact rotator cuff was developed. 1 specimen of each pair received an additive fiber-cerclage of the rotator cuff after plate fixation, and the other one received a plate fixation without an additive fiber-cerclage. Force-controlled hydraulic cylinders were used to simulate physiological rotator cuff tension, while a robot-assisted shoulder simulator performed 4 relevant cases of load: (1) axial loading at 0 degrees, (2) glenohumeral abduction at 60 degrees, (3) internal rotation at 0 degrees abduction, and (4) external rotation at 0 degrees abduction, and imitated hanging arm weight during loading without affecting joint kinematics. A 3-dimensional real-time interfragmentary motion analysis was done in fracture gaps between the greater tuberosity and the head, as well as subcapital. The capacity of the rotator cuff to strain was analyzed with an optical system. RESULTS: Interfragmentary motion was similar between the groups with and without fiber-cerclages, in both fracture gaps and in any of the cases of load. Cerclages did not impair the capacity of the rotator cuff to strain. INTERPRETATION; Provided that unstable 3-part fractures are reduced and stabilized anatomically by a locking plate, additive fiber-cerclages do not reduce interfragmentary motion. Additive fiber-cerclages may be necessary in locking plate osteosyntheses of multiple-fractured greater tuberosities or lesser tuberosity fractures that cannot be fixed sufficiently by the plate.

Safety of contrast-enhanced MR angiography employing gadobutrol 1.0 M as contrast material.

Our objectives were to evaluate the safety of intravenous 1.0-M gadobutrol injections in patients with an indication for contrast-enhanced magnetic resonance angiography (CE MRA) of supra-aortal, pelvic, or peripheral arteries by examining and assessing adverse events, laboratory values, vital signs and ECG findings for clinical significance. In 435 patients, recruited in three multicenter trials for safety evaluations of the new contrast agent 1.0-M gadobutrol, CE MRA was performed with 1.0- to 1.5-T scanners using three-dimensional gradient-echo sequences and phased-array coils. The study population comprised 312 men and 123 women with a mean age of 60.9 years. Two hundred seven patients had an indication for imaging of body arteries and 228 had an indication for imaging of peripheral arteries. Blood laboratory values and urinalysis results of 124 patients as well as heart rate, blood pressure, and 12-lead-electrocardiogram readings of 93 patients obtained during a follow-up period of up to 72 h after the injection of contrast media were available for safety analysis. Contrast media application was performed as intravenous bolus injection of 1.0-M gadobutrol in fixed doses according to the patients' body weight (b.w.) and indication for CE MRA and was followed by a 20- to 40-ml saline flush. Mean dose actually applied was 0.1 0.27 mmol/kg b.w. Flow rate ranged between 0.2 and 2.0 ml/s. Safety evaluations found a good tolerability with only 4.6% of at least "possibly related" adverse reactions and no clinically relevant changes in blood and urine samples including no transmetallation effect on serum zinc values. Analysis of renal tolerance showed no influence on renal function irrespective of preexisting renal impairment. The ECG analysis (rhythm analysis, pace-setting disturbances, conduction disturbances, and time interval measurements, including uncorrected and corrected QT) showed no clinically relevant effect of the injection of 1.0-M gadobutrol on the cardiac conduction system. Intravenous injection of 1.0-M gadobutrol at a dose of up to 0.1 0.27 mmol/kg b.w. in the indication CE MRA is safe and causes no clinically relevant changes in safety parameters such as heart rate, blood pressure, blood and urine laboratory values, and cardiac conduction system.

Diagnostic value of magnetic resonance imaging in Peyronie's disease--a comparison both with palpation and ultrasound in the evaluation of plaque formation.

OBJECTIVE: To compare the value of magnetic resonance imaging (MRI) with palpation and ultrasound in the evaluation of plaque formation in Peyronie's disease. METHODS: 57 patients underwent a standardized diagnostic procedure to evaluate plaque formation consisting of palpation and ultrasonography (7.5 MHz). MRI was performed during flaccidity and during erection induced by Prostaglandin E(1) including intravenous application of Gadolinium-diethylenetriaminepentaacetic acid (Gd-DPTA). RESULTS: With all methods, 93 plaques have been detected in 57 patients. 85 plaques (91.4%) have been evaluated by palpation alone. Using ultrasound, 52 of these 93 plaques (55.9%) were detectable. This is equivalent to 61.1% of the palpable plaques. MRI confirmed 58 of the palpated plaques (68.2%) and exposed 8 primarily not palpable plaques at the penile basis. MRI revealed more palpable plaques than ultrasound, but this finding was not significant (p = 0.083). By means of sonography, calcification was evident in 14 plaques. MRI failed in revealing any calcification. After application of Gd-DPTA, 5 of 57 patients (9%) demonstrated contrast enhancement indicating local inflammation. None of these patients reported on penile pain. CONCLUSIONS: Penile palpation in combination with ultrasound represents the method of choice to diagnose plaque formation in Peyronie's disease. MRI provides better information on plaque formation at the penile basis. Calcification can only be proven by ultrasound, not by MRI. There may be additional information by MRI about local inflammation. A prospective study comparing the histological and MRI findings should be performed to answer the question, if pain is really associated with inflammation.

[Extramedullary hematopoiesis in the paravertebral space]. / Extramedulläre Blutbildung im paravertebralen Raum.

BACKGROUND: Extramedullary hematopoiesis is a response of the organism to a deficient production of blood-forming cells within the bone marrow. It may coincide with some hematologic diseases. Two patients with paravertebral mass lesions representing extramedullary hematopoiesis are discussed. Characteristic findings of extramedullary hematopoiesis are presented along with a review of the literature on this topic. CASE REPORTS: A 76-year-old male with a known myelodysplastic syndrome presented with pneumonia. In addition, he had symptoms of a cauda equina syndrome with complaints of pain and hypesthesia of the lower limbs as well as urinary retention. A 63-year-old female presented with aggravated complaints of the lower thorax, low back pain radiating to the upper left leg, and dysesthesia of both feet. In her past medical history, she had polycythemia vera and a splenectomy. Both patients showed paravertebral and intraspinal lesions located in the thoracic and sacral spine which were regarded as extramedullary hematopoiesis according to the imaging findings in MRI and CT. Radiation therapy showed marked improvement in their neurologic complaints following the initial sessions. CONCLUSION: Clinical presentation, knowledge of the underlying disease and of imaging findings are essential in the diagnosis of extramedullary hematopoiesis. MRI is the imaging modality of choice in the primary diagnosis of extramedullary hematopoiesis. Possible extension of the disease into the intraspinal space can be evaluated with high accuracy and differential diagnosis can be facilitated. In addition, MRI is of use in the accurate planning of radiation fields as well as during follow-up of extramedullary hematopoiesis.