A rare (arteriolo-)capillomedullary venous anomaly of the cerebellum.

A rare (arteriolo-)capillomedullary venous anomaly of the cerebellum was examined with CT, MRI, and angiography. Unlike the usual venous angioma, this case had such extraordinary features as: infratentorial location, involvement of the whole left cerebellum, an arteriolocapillary component and a history of progressive vomiting and chronic constipation in a 7-year-old boy. CT and MRI were consistent with an extensive vascular malformation, but the actual diagnosis was reached by angiography.

[Percutaneous needle biopsy in skeletal metastases. Indications, technique, value and results]. / Perkutane Nadelbiopsie bei Skelettmetastasen. Indikationen, Technik, Stellenwert und Ergebnisse.

Although modern imaging techniques have improved diagnostic specificity in osteolytic and osteoplastic lesions, histological examination is often still mandatory when primary bone tumors or skeletal metastases are concerned. We have developed a percutaneous puncture set, including sufficiently steady, but still fine biopsy needles (1.4-2 mm) and a slow rotating drill accessory. With this set, histological material can be obtained from almost anywhere in the skeleton with local anesthesia low complication risk, and low patient stress and discomfort. Together with the high accuracy of CT- or fluoroscopy-guided puncture (near 95%), this allows biopsies to be taken on an outpatient basis, with broad indications. Biopsy can be used early when making a diagnosis. Tedious searching for the primary tumor can thus be avoided with subsequent economic benefits.

CT and MRI of Gorham syndrome.

Gorham syndrome, also known as massive osteolysis or vanishing bone, is a rare disorder (135 cases reported) leading to extensive loss of bony matrix, replaced by proliferating thin-walled vascular channels. Three histologically proven cases of the disease are reported, including the clinical presentation and modern imaging features with CT (with 3D reconstruction) as well as T1- and T2-weighted MRI. Two cases in young women were located in the pelvis with extensive osteolysis reaching to the acetabulum. The third case in a 2-month-old boy is the youngest case ever reported and involved the humerus. The radiological appearance of the disease is discussed and the importance of the modern imaging methods debated.

Biopsy and quantitative hepatobiliary scintigraphy in the evaluation of liver transplantation.

METHODS: Hepatobiliary scintigraphy with technetium-99m-mebrofenin including a first-pass study of 60 two-sec images and a functional phase of 40 one-min images was performed in 26 patients (42.5 +/- 12.5 yr) in the early postoperative period (9.1 +/- 4.3 days) after liver grafting. Needle biopsy was carried out within a mean of 0.5 +/- 2.2 days of the scintigraphy study. Considering only rejection and cholestasis, biopsy results were used to classify the patients in three groups: control group I (11 patients) with minimal lesions, group II (9 patients) with moderate histologic modifications, and group III (6 patients) with severe dysfunction showing important structural changes. First-pass time-activity curves were used to calculate arterial (alpha-A) and portal (alpha-P) angles as well as a portal perfusion index. Functional time-activity curves were used to define two blood retention indices (BRI1 and BRI2) and two liver uptake indices (LUI1 and LUI2). Excretion was not quantified. RESULTS: Simple linear regression analysis showed a significant correlation between portal perfusion index and BRI1 (p < 0.05, r = -0.43) and BRI2 (p = 0.01, r = -0.53). The validity of the histologic classification was assessed by the existence of significantly different (p < 0.05) mean values for alpha-P, portal perfusion index and LUI1 in the three groups. All other indices could distinguish significantly between groups I and II. Furthermore, arterial angle alpha-A allowed differentiation of group II from group III but not group I from group II; on the contrary, LUI2 and BRI1 distinguished group I from group II but not group II from group III. CONCLUSION: This study demonstrated a close correlation between early biopsy results and perfusion indices in patients with a liver graft as well as uptake parameters determined by hepatobiliary scintigraphy.

Evaluation of RARE-MR urography in the assessment of ureterohydronephrosis.

OBJECTIVE: The goal of this prospective study was to evaluate the value of the fast imaging sequence called RARE-MR urography (RMU) for the diagnosis of ureterohydronephrosis. MATERIALS AND METHODS: Sixty-nine patients underwent this procedure. The results were compared with those obtained by intravenous urography (IVU) and ultrasonography (US). RESULTS: The accuracy of RMU in the detection of urinary tract dilatation and the localization of the level of obstruction was excellent (100%). The determination of the type of obstruction, intrinsic versus extrinsic, was 80% by IVU and 60% for RMU. The RMU sequence alone could not specify the nature of the obstruction. Functional information about the obstructed collecting system could not be obtained. CONCLUSION: The RMU technique may be considered in the following circumstances: contraindications to IVU (allergy to contrast medium, severe renal failure), impairment of renal excretion, and failure to locate the level of obstruction by US. The absence of ionizing radiations favors the promotion of this procedure to study ureterohydronephrosis during pregnancy.

Value of 3D CT imaging in fractured os calcis.

The authors report their experience with 3D computed tomography (CT) in 23 patients with fractured os calcis (several types of fractures) in comparison to classical 2D CT. The diagnostic accuracy was not found to be improved by the three-dimensional representation. 3D CT is affected by reconstruction artifacts and strongly depends on the choice of threshold. However the 3D visualization is appreciated by the surgeons.

Detection of glomus tumor of the finger by dedicated MRI at 0.1 T.

Three glomus tumors of the fingers were detected using a dedicated hand and wrist low field (0.1 T) MR imager equipped with solenoidal coils allowing a FOV of 2 cm. Three-dimensional T1-, T*2-, or T2-weighted images were used (8 contiguous slices of 2 mm thickness). Glomus tumors had low or intermediate signal intensity (2 cases) or no signal (1 case) on T1-weighted images. On T*2- or T2-weighted images they had high signal intensity. MRI findings correlate well with surgery and biopsy.

[Metal abrasion as an imaging artefact in nuclear spin tomography]. / Metallabrieb als Bildartefakt im Kernspintomogramm.

Eighteen patients with vertebral body fractures that had been stabilized by an internal spinal skeletal fixation system were prospectively examined by magnetic resonance (MR) imaging between February 1989 and November 1990 at the Department od Diagnostic Radiology of the University Hospital Freiburg 3-7 days after removal of the metallic implants. In most cases imaging artifacts in the paraspinal extensor muscles were evident on MR studies. These were found especially in the region of the previous site of the metal clip jaw bearing. In a few cases artifacts were also present within the vertebral body and/or vertebral arch, but only if the vertebral body had been surgically reconstructed by transpedicular spongiosa implantation. None or only minor artifacts by abrasion of metal were detected if the (modified Schanz's) screws appeared to be tight at surgical removal of the implants. Therefore, marked metal artifacts on MR imaging retrospectively indicate a chronic straining of the implants, which has been shown to be a risk factor for implant loosening. Additional in vitro studies with powdered metallic alloy showed that as little as 1 mg of metal could be detected as artifacts in routine spin-echo sequences. When the metallic pieces were large enough to be seen on conventional radiographs or computed tomograms, they caused severe, distorting artifacts on MR imaging. It is concluded that MR imaging is the method of choice for detection of small amounts of metal.

MR detection of quantitative and structural changes in human aortic aneurysms.

Collagen is a major component of the extracellular matrix and a determinant of the elastic behavior of the human aorta. To investigate the changes found in aneurysmal degeneration, the authors studied the solid-state hydrogen-1 nuclear magnetic resonance line shape of collagen in aneurysms and normal human aortas. A three-component decomposition of the free induction decay was performed, with collagen characterized by a T2 of about 18 microseconds. The second moment of the collagen line shape was found to be increased in aneurysms (5.3 vs 4.8 G2), while, correspondingly, the T2 of collagen was lower in aneurysms (16.3 vs 17.7 microseconds). This corresponds to a modification of collagen structure and molecular motion. Collagen concentration was lower in nondiseased aortic walls (9.4% vs 7.3%). These results are discussed in reference to the contradictory conclusions in the current literature. The increase in collagen and the modification of its structure and molecular motion are explained by the need to resist an increasing tangential tension due to increased aortic diameter and diminished wall thickness in aneurysms and by intercalation or site binding in the helices or electric dipolar interactions in the less mobile side groups.

In vitro proton NMR study of collagen in human aortic wall.

The authors relate the findings in the 1H solid state line shape (at 60 MHz) of human aortic walls (n = 12) in native state and after histologically controlled selective lysis of collagen and elastin. An analysis of the line shape shows a composite free induction decay (FID) consisting of a low amplitude (3-7%) fast decaying component (T2 approximately 20 microseconds) and a slow decaying one (T2 > 1 ms). The fast component is identified as the protons of the collagen macromolecules. The second moment computed from the experimental fast component of the FID is in agreement with published studies examining the motional characteristics of collagen by multinuclear NMR employing spin labeling. A theoretical second moment is computed for the collagen macromolecular backbone from the atomic positions in the superhelix. Comparison with the observed experimental values allows determination of the step angle (29 degrees) of the fast rotational motion of the collagen strands along their long axis.

Characterization of human aortic collagen's elasticity by nuclear magnetic resonance.

The elasticity of the human aortic wall in longitudinal uniaxial elongation at high strain, known to be determined mostly from tissular collagen's behaviour, is studied and compared to the second moment of the 1H nuclear magnetic resonance (NMR) solid state line-shape, a proton nuclear magnetic resonance (at 60 MHz) characteristic for the molecular motion and the rigidity of the collagen macromolecular backbone. The 1H NMR signal of collagen is identified after selective histologically controlled chemical lysis. The computed second moment of the line-shape shows statistically significant correlation with the slope of the strain-stress curve of the aorta at high strain, thus proving the relationship between a macroscopic tissular elasticity parameter and a macromolecular rigidity characteristic of collagen, a major tissular component. In vivo extension of this technique (e.g., MRI) would allow us to gain information on the biomechanical state of the aorta, a naturally highly stressed and strained tissue.

["Rare" urography by MRI: an alternative to IVU?]. / L'urographie "RARE" par IRM: une alternative à l'UIV?

The authors describe the technique of RARE sequences (Hennig, 1986) and their hydrographic application to urinary imaging, RARE urography. Heavily T2-weighted non-tomographic images of the urinary tract are obtained in less than 30 seconds, without contrast medium or ionizing radiation. The whole urinary tract is visualised on one image with a spatial resolution superior to that of sonography. The semiology of RARE urography is similar to that of the intravenous pyelogram. Silent kidneys are also visualised.

MR imaging of the pericardial cyst.

Findings obtained with magnetic resonance (MR) imaging in four patients with pericardial cyst are reported. MR imaging allowed not only localization and diagnosis in all four cases but characterization of cystic content. MR imaging, including RARE (rapid acquisition with relaxation enhancement) MR hydrography, which shows only liquids with T2s greater than 500 msec, proved to be useful in characterizing the fluid content of a mediastinal lesion and monitoring follow-up. In one case, MR imaging allowed differentiation of a pericardial cyst from a suspected necrotic lymph node in a patient with colic carcinoma, with subsequent correction of staging and therapy. The authors conclude that MR imaging is the method of choice for diagnosis (especially in unusual locations) and monitoring of pericardial cysts and for differential diagnosis of malignant mediastinal cystic tumors that show a solid part.

Proton magnetic resonance relaxation times and biomechanical properties of human vascular wall. In vitro study at 4 MHz.

OBJECTIVES AND RATIONALE: Previous studies have suggested a relationship between tissue magnetic resonance (MR) relaxation times and its biomechanical behavior. To further investigate this relationship, the authors studied 41 human vascular wall samples from different anatomic localizations, including systemic and pulmonary arterial, as well as venous tissues. METHODS: The authors measured water content, proton MR T1 and T2 relaxation times, and two viscoelastic parameters of the samples at 4 MHz. RESULTS: T2, water content, and both viscoelastic variables significantly differed among the five anatomic localizations (P less than .05). Both T1 and T2 were significantly (P less than .05) and linearly related to viscoelastic parameters. Multiple linear regression showed that both viscoelastic parameters of a sample can be predicted from the measured values of T1 and T2. CONCLUSIONS: These results provide a basis for characterizing the mechanical stress of a tissue by knowing its MR relaxation times.

[Diagnostic procedures in acute gastrointestinal hemorrhage]. / Diagnostisches Vorgehen bei akuter gastrointestinaler Blutung.

In gastrointestinal bleeding, the diagnosis is predominantly made by endoscopy. However, if the bleeding site is in a part of the intestine that cannot be reached by endoscopy, than the diagnosis is based on radiological and scintigraphic methods. In the past 5 years 35 patients with such cases of gastrointestinal bleeding had angiography and/or scintigraphy (n = 15) in our department. Based on our retrospective study of those cases, we advocate a management protocol for such patients based on the hemodynamic presentation.

[Computerized tomography diagnosis of scaphoid fracture and pseudarthrosis in comparison with roentgen image]. / Computertomographische Diagnostik bei Skaphoidfraktur und -pseudarthrose im Vergleich zur Röntgenaufnahme.

Twenty eight patients with fourteen acute scaphoid fractures and fourteen with scaphoid non-union were examined with standard X-rays in two planes, special scaphoid projections and computed tomography. Nine scaphoid fractures were revealed by both standard X-rays and CT, whereas four fractures could only be detected by CT. Computed tomography should be used when there is clinical suspicion of scaphoid fracture but standard radiographs remain negative. All carpal bones should be examined. Fourteen patients with suspected scaphoid non-union were examined. In twelve patients, scaphoid non-union seemed to be complete in standard X-rays, whereas CT showed a bony bridge between the proximal and distal fragment. Another patient showed bony union. Two patients showed no non-union in standard X-rays. One was confirmed after a Matti-Russe procedure, but the bone graft was dislocated, causing restricted wrist motion. One scaphoid non-union was demonstrated by CT. Two patients showed signs of additional carpal fractures. Diagnostic applications of CT for scaphoid non-union include the determination of the exact location of the fragments and the evaluation of post-traumatic cysts, thus simplifying pre-operative planning.

[Uretero-arterial fistula. A rare cause of massive hematuria]. / La fistule urétéro-artérielle. Une cause rare d'hématurie massive.

Ureteroarterial fistulae is a rare condition, with less than 25 reported cases. We describe such a fistula in a young female patient, after radiation therapy for cancer of the cervix and rectovaginal and vesicovaginal fistulae requiring sigmoidostomy and an ureteroureterostomy after long-lasting ureteral intubation. Angiography demonstrated the fistula and the reflux of contrast medium up to the pyelocalyceal cavities, and allowed establishing the origin of the massive hematuria, which caused the patient's death.

[Percutaneous interventions on the bile duct in obstructive jaundice. A meaningful or excruciating prolongation of life?]. / Perkutane Interventionen am Gallengang beim Verschlussikterus. Sinnvoll oder qualvolle Lebensverlängerung?

The percutaneous transhepatic access to the bile duct opens a wide spectrum of diagnostic and therapeutic procedures. This means specific diagnosis and therapy of the obstructive jaundice even in patients in bad general conditions and therefore unfavourable prognosis. As in most cases curative therapy is no longer possible, survival time can be taken into consideration. There are no great problems concerning the performance of technical procedures. But it is the justifiability of the interventions that has to be reconsidered in each of the cases. The facts that the quality of life can be improved and the possibility to discharge the patient as soon as possible should be the guidelines in having the patients undergo these therapeutic procedures. The evaluation of our case material from 1985-1991 show that just in this respect the introduction of the endoprosthesis (thick calibrated endoprosthesis, stents) is a great progress, with a mean survival time between 8 and 10 months, and with normalization of laboratory values in 75-100%.

[MR tomography of aneurysmal bone cyst]. / MRT der aneurysmalen Knochenzyste.

The preoperative findings of magnetic resonance imaging (MRI) in six histology-proven aneurysmal bone cysts (ABC) are examined and compared with previous publications concerning MRI of ABC. The signal intensities differ considerably, and not all of our cases conform with the literature data. They can be summarised in three different subheadings: one form that is very inhomogeneous in T1- and T2-weighting, with fluid-fluid levels in the cystic spaces; one intermediate form without fluid-fluid levels, which is inhomogeneous only in T2-weighted images; and finally, an unusual form of ABC that has homogeneous low signal both in T1- and T2-weighting, and which has not been described in literature so far.