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This paper determines the usefulness of three-dimensional (3D) phase-contrast (PC) magnetic resonance (MR) angiography with 3D display in characterizing large intracranial saccular aneurysms.Eight patients referred for non invasive confirmation of unruptured aneurysm (n=9) detected by conventional CT and/or MR imaging were studied by 3D PC (VENC of 20 cm/s, 3 axes) in axial acquisition localised on the circle of Willis using a 0.5 T unit (Vectra, GE). We used 3D display images to assess the feasibility of selective treatment. Results were correlated with catheter angiograms in 3 patients.In two thirds of the cases, location and size of the orifice, size of the sac, and clarification of parent artery were clearly provided allowing prediction of therapeutic management. In the remaining cases results remained doubful because of lack of spatial resolution. The benefit of the method was coupled with the clinical status of the patients to influence the final decision.3D PC MR angiography with 3D display has emerged as an improvement in predicting therapeutic management, and is especially useful in large unruptured aneurysms in elderly or ill patients.

Summary The aim of this study was to identify the functional anatomic factors involved in the maintenance or disturbance of flow in the vertebral aa. during atlanto-axial rotation. Fourteen healthy volunteers were studied by magnetic resonance angiography (MRA) by a three-dimensional sequence in phase contrast centered on the vertebral aa. at the level of the cranio-cervical junction before and after left rotation of the head A decrease in the signal intensity of the arterial flow was sought for. The results were compared to the posterolateral development of the loop of the vertebral a. in its atlanto-axial segment in neutral position, and to the measurement of the angular opening between the atlas and axis in dynamic position. Seven subjects also had a three-dimensional CT study (3D CT) of the bony relations of C1 and C2 after rotation. In 4 subjects a disturbance of flow in the right vertebral a. was observed in the transverse foramen of C2. This occurred when two factors were combined: an under-developed atlanto-axial arterial loop and a C1–C2 angle exceeding 35° in maximal rotation. In the other subjects a well-developed arterial loop and/or a C1–C2 angle of less than 35° in maximal rotation were factors preserving the arterial flow. The risk factor associated with the C1–C2 angle seemed correlated in 3D CT with loss of the usual asymmetric character of rotation. A clinical application is reported with a case combining chronic rotational dysfunction of the cranio-cervical junction as shown by 3D CT and complete compression of the vertebral a. in MRA, confirmed by conventional angiography. A knowledge of this physiopathologic mechanism allows clinical detection and evaluation of the risk of any effect of pathology of the cranio-cervical junction on the vertebral a.

Summary The functional anatomy of the spinal column has mainly been studied in the cadaver. The aim of our study was to determine in vivo the normal axial rotation of the cervical column using computed tomography (CT). Sixty subjects, divided into decades from 20 to 80 years of age were studied. The CT protocol comprised an axial cut at the level of the skull base (C0) and at each vertebral level in the neck, in the neutral position (with the nasal septum vertical) and during rotation of the head. To reduce the exposure to irradiation the subjects were divided into two groups: 40 were studied from C0 to the fifth cervical vertebra (C5) with unilateral rotation at C0 of 10°, 20° and 40° (20 rotations to the left and 20 to the right), and 20 subjects were studied from C0 to the first thoracic vertebra (T1) with a maximum rotation at C0 to left and right. The angular position of a vertebra was defined as the anteroposterior axis with reference in the neutral position to the axis of C0, and in rotation was related to its original axis. At each vertebral level the mean angle of rotation and its standard deviation were calculated (n=30) for the successive intermediate and maximum rotations at C0 level. The rotation of the cervical spine took place mainly at two levels: 58% between C1 and C2 and 24% between C3 and C6. The pairs of vertebrae C0/C1 and C2/C3 provided functional couples where the rotation was minimal. Rotation of the lower cervical spine occurred very early. The percentage of rotation with respect to C0 of each cervical vertebra was constant during the successive rotations. The neutral positions of the vertebrae below the atlas were variable. The findings on rotation to left and to right were comparable. This study determined in vivo the distribution of rotation at each vertebral level of the cervical spine during partial and maximum rotation of the skull base. It facilitates the application of CT to the examination of disorders affecting the rotation of the cervical spinal column.

Abstract: We describe the evolution of parenchymal cerebral cysticerci on MRI, to assess signs of early cyst degeneration. We studied 15 lesions in four treated and one untreated patient. MRI was performed before therapy and repeated in the 1st month after each course of anticysticercus drugs, every 4 months during the 1st year and then annually; the follow-up period was 8–48 months. Lesions were classified according to changes in four features: cyst content and capsule signal, gadolinium enhancement and oedema signal. We were able to recognise each of the pathological phases; five MRI stages were identified. Stage 1 showed oedema and/or nodular gadolinium enhancement in the tissue invasion phase; stage 2 was cerebrospinal fluid-like signal within a cyst in the vesicular phase; stage 3 showed a thick capsule with an impure liquid content signal and surrounding oedema, in the cystic phase; stage 4 showed the disappearance of the cyst fluid content signal in the degenerative phase; stage 5 showed a calcified lesion in the residual phase. Stage 1 lesions disappeared after therapy; the other progressed from one stage to another. Stage 4 indicated the end of viability of the parasite and determined the point after which treatment was useless. On T2-weighted images changes in the cyst content differed according to the history of the lesion; nodular low intensity followed the natural degeneration of the parasite and a mixed fluid signal with punctate low signal seemed to represent the specific result of therapy. MRI staging can help in the evaluation of indications for treatment and facilitate clinical therapeutic trials.

Summary Traditionally, the linea alba represents the principal route of approach in abdominal surgery and in consequence it is the commonest site of incisional hernia. The aim of this study was to review its morphology and to study its mechanical parameters of resistance, deformation and elasticity in order to compare these with the prosthetic materials most often used in the treatment of incisional hernia. Forty fresh cadavers were dissected and tests with a dynamometer and “bursting strength tester” were performed on samples taken from the linea alba at three leveels: supra-umbilical, subumbilical and umbilical. Forty abdomino-pelvic scans were analysed. The morphologic results allowed definition of diastasis of the rectus mm. in terms of subject age: below 45 years of age diastasis was considered as a separation of the two rectus mm. exceeding 10 mm above the umbilicus, 27 mm at the umbilical ring and 9 mm below the umbilicus; above 45 years of age the corresponding values were 15 mm, 27 mm and 14 mm respectively. In the biomechanical study the subumbilical region exhibited a coefficient of elasticity greater than that of the supra-umbilical portion, but no significant difference in resistance was found between the different parts studied. The biomechanical results are compared with the corresponding data for prosthetic materials.

Summary A three-dimensional analysis of atlantoaxial rotation was made by computed tomography in ten healthy subjects. The method described allowed study of spatial relations between C1 and C2 interspace under both static and dynamic conditions, using a projection in a fixed transverse plane. The results demonstrated an axis of rotation for C2 slightly anterior to that for C1. Asymmetric rotation was observed, the separation between the transverse formaina of C1 and C2 being less marked on the side opposite to the direction of rotation of the head. This use of CT and these anatomic findings may be useful in the study of disorders of atlantoaxial rotation and their effect on the vertebral arteries.

Summary The authors report the anatomic and radiologic findings in a case of ectopic origin of the right renal artery in front of the T11–12 intervertebral disc. This seems to be an extremely rare variant, and the rarity of the reported cases is such as not to allow definition of a percentage incidence. An explanation of this variant may be found in modern concepts of the organogenesis of the renal artery.