Search

Peripheral arterial disease is a main cause of morbidity in industrialised countries. It chiefly affects older people. The most common causes are atherosclerosis and vasodilatatory abnormalities. In the presence of unexplained leg symptoms, peripheral arterial disease can be diagnosed or ruled out by non-invasive diagnostic methods such as history, clinical examination and the measurement of ankle and brachial artery pressure by Doppler ultrasound, as well as by calculating the ankle brachial index. Colour coded duplex sonography, computer tomography angiography, magnetic resonance angiography and arteriography are the imaging modalities used. Current diagnostic strategies are analysed for the different peripheral artery diseases.

Clinical radiology is a key to the management of bowel obstruction. Plain abdominal radiographs combined with history, clinical exam, and laboratory findings are essential for further individualized strategies. If the cause of obstruction is obvious after plain films and there is a need for emergent surgery, no further imaging is required. In all other cases, multislice CT with at least intravenous and rectal contrast is the method of choice due to its broad diagnostic spectrum. If CT is not available, contrast enema is recommended in suspected large bowel obstruction. Oral administration of water-soluble contrast agents has no significant value in the workup of bowel obstruction.

Introduction: Usually, standard radiographs are used for postoperative quality follow-up after ACL reconstruction. However, with the use of hamstring grafts and bioabsorbable implants, accurate assessment of the tunnel and implant position is impossible. The graft and its relation to anatomical landmarks cannot be evaluated directly. MRI is an alternative to radiography, permitting direct graft visualization and 3-dimensional assessment of the tunnel position, but it is expensive and time consuming for routine use. The aim of this study was to develop a simplified MRI protocol and to evaluate it for routine postoperative quality follow-up after ACL reconstruction., Materials and Methods: Various scanning protocols were tested in a series of 105 patients and evaluated for image sharpness, clarity of the structures, susceptibility to artefacts, applicability regarding precise analysis of graft and tunnel position, and time consumption. One simplified specific scan protocol was then defined and applied in a series of 60 consecutive patients after hamstring ACL replacement. The position of the femoral and tibial tunnels was measured in the sagittal, coronal and axial sections and classified according to Harner (femoral) and Stäubli (tibial). Impingement of the graft in the intercondylar roof was analysed according to Howell. The position of the bioabsorbable interference screws was assessed., Results: Scan protocol: T2-weighted gradient-echo sequences (GRE) with TR 246 ms, TE 11 ms, flip angle 25 degrees, 2 mm sections and a 256 x 256 matrix yielded the best image quality of tendon grafts and bone tunnels with tolerable time consumption (average scanning time per patient 1 min 40 s). Altogether 8-16 sections were obtained for every patient. Tunnel placement: 46/60 (77%) of the femoral tunnels were in zone 4, 13/60 (21%) at the border of zones 3 to 4, 1/60 (2%) in zone 3 in the sagittal plane (Harner). The femoral tunnels in the axial plane were at 10:30 o'clock in 32/60 (53%), at 11:00 o'clock at 24/60 (40%) and at 10:00 o'clock in 4/60 (4%) patients. The mean distance of the anterior border of the tibial tunnel from the anterior cortex was 39% (+/- 4.9%) related to the total sagittal diameter of the tibia. There was no graft impingement. The position of the interference screws was anterior to the grafts in all cases., Conclusion: Simplified MRI sequences can be used for postoperative quality follow-up after ACL replacement and are an alternative to standard radiographs giving more specific and precise information regarding tunnel position and screw placement. Analyzing the bone tunnels in a series of 60 patients demonstrated that correct assessment of tunnel placement after arthroscopic ACL reconstruction is feasible using this simplified MRI technique.

The purpose of this study is to compare triphasic helical CT and fast MRI with respect to detection, characterization and staging of suspected renal masses. To achieve this triphasic helical CT (plain, corticonephrographic and tubulonephrographic phase) and MRI with fast T(1) weighted and T(2) weighted sequences were performed in 29 patients with a suspected renal lesion. Image quality, lesion characterization and lesion extent were assessed for both methods in all patients. The acquisition phase for CT and the image sequence for MRI offering the best image quality and best diagnostic information regarding renal parenchyma, renal vessels, detection of enlarged lymph nodes, and other abdominal organs were determined. Histologically confirmed renal cell carcinomas (n=18) were staged based on the Robson classification. Quantitative data were obtained from operator-defined regions of interest (ROIs) in all acquisition phases (CT) and all image sequences (MRI). For most criteria the rating of image quality for helical CT was generally higher as compared with fast MRI. CT and MRI detected all 24 histologically proven masses, while no false positive solid tumour was diagnosed with both imaging modalities. All three acquisition phases in CT and all applied image sequences in MRI were regarded as necessary in order to gain important diagnostic information. Altogether, 12 of 18 renal cell carcinomas (67%) were correctly staged by CT and MRI. Helical CT and fast MRI allow the correct detection and characterization of suspicious renal lesions. Both imaging modalities can be recommended for clinical routine application. Although the correct histological staging of renal cancer remains difficult for both imaging methods, both are excellent in providing the critical staging information needed before surgery. Helical CT offers a significantly shorter acquisition time to cover the entire abdomen.

Objective: High soft-tissue contrast and multiplanar imaging capabilities of MRI may be advantageous in biopsy guidance compared to CT. We report our first results with MR-guided core biopsies using a closed 1.0 T MR imager., Methods and Patients: In ten patients, seven liver lesions and one lesion each in the muscle of the back, the gluteal muscle and in the breast were biopsied under MR guidance using MR-compatible needles (Tru-Cut type, 18G and 14G). For control scans T1-weighted turbo-spin-echo (TSE), gradient-echo and T2-weighted TSE sequences were used., Results: In all patients, the suspicious lesions and the biopsy needle were exactly delineated in MR control scans. In nine out of ten patients, the suspicious lesion was clarified histologically. Controls of needle position in a second plane were performed twice. Pushing the inner stylet alone resulted in a distortion of the needle in several cases in its flat area. The small diameter of the MR gantry was inconvenient for a few patients. One complication (intrahepatic bleeding) was observed, which healed up without consequences., Conclusion: Using a closed 1.0 T MR imager MR-guided core biopsies can be conducted efficiently. Core biopsies should be taken by pulling and pushing the outer cannula. Advantageous compared to CT are the multiplanar imaging capabilities, while the smaller gantry is disadvantageous.

Purpose: Comparative evaluation of specimens obtained with different MR-compatible biopsy systems and a conventional ferromagnetic system., Methods: Biopsies of a pig liver were performed post-mortem with three different MR-compatible (Somatex; E-Z-EM; Daum) and one conventional biopsy system (Somatex), five with each device. The specimens were measured and the histopathological quality was graded on a scale from 0 (no tissue) to 9 (best). The tip of the needle was examined with an electron microscope before and after biopsy to demonstrate abrasion., Results: The histopathological score between the first and fifth specimen taken with one biopsy device showed no significant difference. The conventional system yielded significantly better results in nearly all categories (p < 0.05) than the MR-compatible biopsy systems. The areas of the specimens obtained with the MR-compatible biopsy systems (4.27-5.99 mm2) were significantly smaller than those from the conventional system (9.98 mm2). The needle tip abrasion of the different biopsy systems determined by electron microscopy showed no substantial difference., Conclusion: Specimens obtained with MR-compatible biopsy systems compared to conventional biopsy systems are of lower histopathological quality. This might be caused by a smaller side notch of the MR-compatible biopsy devices. There was no difference in abrasion of the needle tip due to the softer, non-ferromagnetic alloys.

Purpose: To estimate the accuracy of the determination of tip position of MR compatible biopsy needles based on signal voids and artifacts in MR guided biopsies., Method: In a nylon grid phantom an MR compatible 18G needle (E-Z-EM) was measured in a 1.0 T imager using TSE- and FFE-sequences of 20 s and 40 s duration in 34 different orientations of needle versus B0, frequency and slice selection gradient. 4 radiologists with no experience in the evaluation of signal void artifacts estimated the needle tip positions from needle tip artifacts. The readers determined the needle tip before and after a 15 minute training session based on high resolution images with explanation of size and shape of specific artifacts of biopsy needles in 12 different orthogonal or parallel orientations to B0 and frequency encoding gradient that are possible if the needle lies parallel to the slice, i.e. orthogonal to the slice selection gradient. The values obtained before and after the training session were compared to the real position of the needle tip., Results: Mean distance of actual needle tip and tip position as determined from images was 1.8 +/- 2.3 mm in TSE-versus 2.5 +/- 1.2 mm in FFE-images, with the needle length overestimated. After a 15 minute training session the positioning error decreased significantly to 0.2 +/- 1.8 mm for TSE-sequences and to 1.0 +/- 1.8 mm for FFE-sequences. A higher accuracy of tip localization was obtained with TSE sequences., Conclusion: In MR guided biopsies using FFE- and TSE-sequences the needle position can be more accurately determined if the reader is familiar with the 12 orthogonal or parallel positions of the needle with respect to B0 and frequency encoding gradient and the corresponding artifacts.

Purpose: Small suspicious breast lesions that are only visible at MR imaging were preoperatively marked with a hook wire under MR-guidance to allow the removal of the lesion with tissue-sparing surgery., Method: In all patients the suspicious lesions were marked preoperatively under MR guidance with a hook wire using a commercially available stereotactic device. Interventions were performed with MR guidance on a 1.0 T and on a 1.5 T system., Results: In 19 patients 22 lesions were localized. One lesion was missed and removed in a second procedure. The mean duration for localization was 66 +/- 20 min (range 38-119 min). In two patients two lesions were localized. The mean deviation of the wire tip to the lesion was 2.0 +/- 2.6 mm. In this series, 6 of 22 lesions were malignant. The mean diameter of the lesion was 7.6 +/- 2.6 mm (range 3-14 mm)., Conclusion: Suspicious breast lesions detectable only in MR imaging can be accurately localized with a hook wire preoperatively under MR control to remove the lesion with a tissue-saving surgery.

Purpose: To compare magnetic resonance imaging (MRI) and X-ray tomography in assessing the type of fracture, degree of comminution and amount of articular surface depression in acute tibial condylar fractures and to describe the associated soft tissue injuries diagnosed with MRI., Method: 27 patients with acute tibial plateau fractures were investigated using linear X-ray tomography and MRI employing T1-weighted and proton density turbo spin echo, STIR, and T2-weighted gradient echo images. Fractures were classified according to the AO classification system. The degrees of depression and comminution were measured and soft tissue injuries were recorded., Results: Fractures were classified as type B1 in 7, as B2 in 6, and as B3 in 6 cases by MRI. More complex C-type fractures were diagnosed in 8 cases. MR and X-ray grading were consistent with the exception of two B3 fractures, which were graded as B1 by X-ray tomography. X-ray tomography under-estimated the degree of comminution 63% of the patients had either meniscal tears or complete ruptures of their cruciate or collateral ligaments. Ten meniscal tears were diagnosed in 9 of 27 patients. Complete tears of the anterior cruciate ligament were seen in 4, and avulsions of the posterior cruciate ligament in 2 patients., Conclusion: MRI allows a detailed assessment of acute tibial plateau fractures and can replace conventional X-ray tomography. The high rate of fracture-associated soft tissue lesions makes MRI an especially valuable tool.

Recurrent parotitis is rare in childhood. Its occurrence is characterized by recurrent episodes of swelling and pain in the parotid gland, which are usually accompanied by fever and malaise. Inflammation usually resolves spontaneously during adolescence. The disorder is a condition of unknown etiology. Sialectasis and stricturing occurs in the distal ducts, whereas inflammation of the gland and duct epithelium is probably caused by a low salivary flow rate. Which one can be considered the primary event or secondary change remains unknown. The main-stay of diagnosis is sialography, which depicts typical intraparotidal duct system lesions as strictures or ectasias and excludes sialolithiasis. We here report two 10-year-old male monovular twins who suffered from recurrent swelling and pain in only their left parotid glands. Symptoms were noted approximately every 6 weeks in both patients strictly. Characteristic sialectasis of the distal ducts was demonstrated by magnetic resonance-sialography. Our findings support the hypothesis that recurrent parotitis is caused by a congenital abnormality of the salivary gland ducts. Diagnostic imaging was performed by magnetic resonance imaging during the acute phase of the disease. This technique helps to make the diagnosis without retrograde application of a contrast agent.

This review presents the options and limitations of MRI in non-vascular diseases of the mediastinum and the chest wall. In numerous thoracic pathologies, MRI is a useful supplement to spiral CT. This imaging procedure also allows a contrast-media-free differentiation of solid tumors and vascular lesions (e. g., aortic aneurysms). The advantages of MRI over CT are particularly useful when multiplanar tumor imaging is required prior to surgery to establish the exact spatial relationship between tumor and the other mediastinal structures. Primary indications for MRI in diseases of the mediastinum and chest wall are therefore: (a) tumors of the posterior mediastinum for determining their position in relation to the neural foramina and the spinal canal; (b) chest wall tumors; (c) preoperative multiplanar imaging of primary mediastinal tumors; and (d) contraindications against CT exams with iodine contrast media.

Purpose: To evaluate the value of rapid T2-weighted turbo-spin sequences (TSE), turbo-spin-echo sequences with shortened echo spacing (UTSE), gradient-and-spin-echo sequences (GraSE) and T1-weighted echo-planar imaging (EPI) in comparison with conventional spin-echo sequences (SE) in the diagnosis of focal liver lesions., Methods: 20 patients with malignant focal liver lesions underwent magnetic resonance imaging at 1.0 tesla., Results: The use of fast T2-sequences (TSE, UTSE, GraSE) reduced the examination time to about 35-50%. Artifacts were reduced compared with the conventional T2-SE sequence. Quantitative analysis demonstrated that UTSE imaging had the highest tumor/liver contrast-to-noise ratio (CNR) followed by TSE, T2-SE and GraSE sequences. CNR with EPI was lower than with the T1-SE sequence (p < 0.05)., Conclusion: Turbo-spin-echo sequences with shortened echo spacing yield a shorter imaging time and improved image quality without loss of signal intensity in tumor/liver-CNR, compared with conventional T2-pulse sequences in liver imaging at 1.OT.

Purpose: MR spectroscopy allows the acquisition of a two-dimensional array of spatially resolved proton spectra of the human brain, known as MR spectroscopic imaging. Here the examination protocol and clinical applications in focal brain lesions are presented., Method: An array of data is acquired from a tissue slice positioned in the brain. These data can be presented as a set of spectra, in which each spectrum is allocated to a specific position in the sample, or as a set of images or "metabolite maps"., Results: The NAA signal typical for neuronal tissue is decreased in the centre of brain tumours as well as in brain infarcts. The intensity of the choline signal is increased in solid tumour tissue, whereas it is reduced in infarcts., Conclusion: Spectroscopic imaging reveals metabolite alterations in and around focal lesions. The spatial resolution of spectroscopic imaging enables matching with other macro-morphological or functional imaging methods like positron emission tomography.

The effect of section alignment and distance in volumetric determination of myocardial mass by means of cardiac magnetic resonance imaging (MRI) was studied in 19 isolated pig hearts. Double angulated views taken through the short axis of the heart with a slice thickness of 10 mm and slices at a distance of 0 mm, 1 mm, 3 mm and 5 mm produced accurate left ventricular measurements with cardiac MRI. Measurements in the long axis of the heart resulted in a marked underestimation of myocardial mass; depending on slice intervals, there was an error between 13% and 20%. In vivo measurements in 35 subjects confirmed the effect of section alignment. Measurements in the long axis of the heart produced results of 139.9 +/- 31.7 g, significantly less than measurements in the short axis of the heart of 157.8 +/- 32.3 g.

MRT with gadolinium-DTPA (0.1 mmol/kg body weight) was performed in 10 patients with renal insufficiency requiring dialysis and the clearance of gadolinium-DTPA was studied. After 3 dialysis on 3 successive days more than 97% of the initial concentration of gadolinium-DTPA had been eliminated. Average half-life was 1.87 hours. There were no side effects in any of the patients. Close laboratory observation of liver function showed no significant changes during the period of study. No contra-indication for the use of this contrast medium in patients with renal insufficiency requiring dialysis was found during this study.

Forty hands of 39 patients with rheumatic joint disease were examined by MRT. The method differentiates between inflammatory exudative and proliferative processes in soft tissues and bone. T2-weighted images provided criteria for judging the activity of the disease. MRT provided better demonstration of the soft tissues than just conventional radiography. The methods were of equal value for showing bone lesions. MRT is suitable as a means of diagnosing rheumatoid changes in the hand.

Five healthy children and 16 children, ages 6-17 years, who had been operated on for anorectal atresia underwent magnetic resonance (MR) imaging of the pelvis. The development of sphincter muscles and the location of the pulled-through intestine in relation to the sphincter muscles were evaluated by a muscle score. There was good correlation between MR muscle score and clinical continence score. MR imaging provides additional information for therapeutic management and surgical procedures to improve continence.