Metanephric adenoma diagnosed on biopsy in an infant: a case report.

BACKGROUND: Metanephric adenoma is a rare benign renal tumor of the kidney, uncommonly observed in children. It is often misdiagnosed preoperatively as a malignant neoplasm, leading to an unnecessary nephrectomy. The challenge is to make the right diagnosis preoperatively and therefore manage it with conservative surgery. We report a case of a child with metanephric adenoma who underwent nephron-sparing surgery. CASE PRESENTATION: A renal tumor was discovered fortuitously in an 18-month-old Caucasian girl with several congenital malformations. Investigations showed a 28 × 27 × 27 mm left renal mass centrally located, well defined, nonvascularized, with no calcifications and which compressed the adjacent renal tissue. Furthermore, there were no signs of metastasis. The decision of a multidisciplinary meeting was to perform a computed tomography (CT)-scan-guided biopsy. Histologic examination concluded it was a metanephric adenoma. We performed a left open partial nephrectomy via a flank retroperitoneal incision. The final histopathological examination confirmed the diagnosis. The postoperative course was uneventful. CONCLUSION: Preoperative diagnosis of metanephric adenoma is challenging. Because of the high probability of unnecessary radical nephrectomy, preoperative biopsy can be safe and determining to guide a more conservative approach so nephron-sparing surgery can be performed.

Midbrain deafness with normal brainstem auditory evoked potentials.

The authors report two cases of patients with word deafness. The word deafness occurred after a head injury for the first patient and after an arterio venous malformation embolization for the second patient. MRI demonstrated bilateral lesions of the inferior colliculi but brainstem auditory-evoked potentials (BAEP) were within normal limits. These cases demonstrated that lesions involving the two inferior colliculi induced pure word deafness but do not affect BAEP.

Hemispheric asymmetry and corpus callosum morphometry: a magnetic resonance imaging study.

Previous post-mortem studies (Aboitiz, F., Scheibel, A.B., Fisher, R.S., Zaidel, E., 1992. Brain Res. 598, 154-161 and Aboitiz, F., Scheibel, A.B., Zaidel, E., 1992. Brain 115, 1521-1541) have shown an inverse association between asymmetry in perisylvian areas and the size of a specific segment, the isthmus, of the corpus callosum (CC) in males. The purpose of this work was to study in vivo the association between hemispheric asymmetry and the total size of the CC in 35 right-handed subjects (16 males, 19 females; mean age 24.9 +/- 3.9). An MRI scan was performed for each subject. The area of the right (RH) and left (LH) hemispheres were measured from images in the sagittal plane and the area of the CC from images in the mid-sagittal plane. The index of hemispheric asymmetry was absolute value((LH - RH)/[(LH + RH)/2]). There was a negative correlation between the absolute value of hemispheric asymmetry and the size of the CC in males (r = -0.55, P = 0.03) but not in females (r = -0.20, P = 0.42). These findings, like those of Aboitiz et al. (Aboitiz, F., Scheibel, A.B., Zaidel, E., 1992. Brain 115, 1521-1541), suggest a sex-dependent decrease in interhemispheric connectivity with increasing hemispheric asymmetry.

Intracranial extension of an idiopathic orbital inflammatory pseudotumor.

Idiopathic orbital inflammatory pseudotumor (IOIP) with endocranial extension is very unusual. The authors used CT and MR to diagnose IOIP and demonstrate the presence of intracranial extension of orbital and lacrimal gland lesions. While providing additional evidence of IOIP having intracranial extension, this case report emphasizes the need to include IOIP as a possible differential diagnosis when radiologic explorations reveal lesions extending from the orbit to intracranial structures.

Are the brains of monozygotic twins similar? A three-dimensional MR study.

PURPOSE: The role of genetic mechanisms and the influence of environmental events in human brain development have been difficult to evaluate. The purpose of this study was to compare the cerebral cortical morphology and midline structures of monozygotic twin pairs using MR imaging. METHODS: Six observers, blinded to twin pairings, evaluated the 3-D renderings of the cortical surface and midline structures from MR images of seven monozygotic twin pairs. A morphometric analysis of the corpus callosum and of the distance between the anterior and posterior commissures was also performed. RESULTS: Despite surprising anatomic differences, the brains of the twin pairs were similar enough to enable the observers to distinguish twin pairs from unrelated subjects. Five of six observers correctly identified the brains of all seven twin pairs; the remaining observer failed to make a correct match in only one of seven pairs. Three of six observers identified the midline sagittal images of the related twins in all seven pairs, and the other three identified the related midline sagittal images in five of seven pairs. The results were statistically significant. CONCLUSION: Although the observed differences in morphologic characteristics between twins necessarily reflect nongenetic influences, the cortical patterns and midline structures of monozygotic twins probably are genetically similar.

A technique of measuring the precision of an MR-guided stereotaxic installation using anatomic specimens.

PURPOSE: To develop a method for direct measurement, using anatomic specimens, of the precision of MR-guided stereotaxic location and to describe its application to a 1.5-T MR unit with a Leksell stereotaxic frame. METHODS: Small pieces of gelfoam (1 X 1 X 1 mm), soaked in gadopentetate dimeglumine, were stereotaxically introduced into formalin-fixed human heads using a Leksell D (three experiments) or G (nine experiments) stereotaxic frame. The head and the frame were then introduced into a 1.5-T MR unit. The target coordinates (as set on the stereotaxic frame by one investigator) were then compared with the MR-determined stereotaxic coordinates (calculated independently by another investigator). The imprecisions Ex, Ey, and Ez in each direction were defined as the differences between the calculated and the chosen coordinates. RESULTS: Regarding the three targets studied with the D frame, mean imprecision Ex was 1.08 +/- 0.50 mm (mean +/- SEM), Ey 0.83 +/- 0.58 mm, and Ez 0.75 +/- 0.25 mm. For the nine targets studied with the G frame, Ex was 0.48 +/- 0.17 mm, Ey 0.69 +/- 0.14 mm, and Ez 0.82 +/- 0.13 mm. Statistical analysis of the results showed no significant difference between Ex or Ey and half the size of a pixel, indicating that, in the axial plane, stereotaxic MR precision is limited only by pixel size. A statistically significant difference was observed in the coronal plane between Ez and half the size of a pixel, but it must be stressed that Ez remained smaller than 1 mm. CONCLUSION: MR-guided stereotaxic location can be used with confidence for most diagnostic, functional, and therapeutic procedures.

MR determination of hippocampal volume: comparison of three methods.

PURPOSE: To determine whether measurements of the volume of the hippocampal formation obtained from a three-dimensional acquisition not perpendicular to the hippocampus are statistically different from those obtained from a perpendicular acquisition. METHODS: Both hippocampi were studied in 10 healthy volunteers with two three-dimensional acquisitions, allowing three different volume-calculation protocols: (a) on sections from a coronal 3-D acquisition not perpendicular to the axis of the hippocampal formation (NOPERP protocol), (b) on sections obtained with the same acquisition but reformatted perpendicular to the axis of the hippocampal formation (REFOR protocol), and (c) on sections from a coronal 3-D acquisition perpendicular to the axis of the hippocampal formation (PERP protocol) obtained with the patient's head tilted backward. To obtain measurements of the volume of the hippocampal formations, an accurate 3-D processing technique was used to segment the hippocampus. In all subjects, two hippocampal formation right-left asymmetry indexes were calculated by using each of the three protocols. RESULTS: For the right hippocampus, the mean volume was 3.42 cm3 (NOPERP protocol), 4.18 cm3 (REFOR protocol), and 3.91 cm3 (PERP protocol). For the left hippocampus, the mean volume was 3.29 cm3 (NOPERP protocol), 4.02 cm3 (REFOR protocol), and 3.74 cm3 (PERP protocol). For both hippocampi, the differences of the mean volumes were significant between each protocol. However, for both hippocampi, a high correlation was observed between volumes obtained with the different protocols. For the two asymmetry indexes, there were no significant differences for the means obtained with the three protocols. CONCLUSION: With the use of 3-D acquisitions in the study of hippocampal formation biometry, different procedures lead to significant variations in the absolute values of the volume of the hippocampal formation. However, there is a strong correlation between the results obtained by each method.

Three-dimensional computed tomographic angiography in detection of cerebral aneurysms in acute subarachnoid hemorrhage.

OBJECTIVE: Three-dimensional computed tomographic angiography (CTA) is a recently developed imaging modality. We demonstrate the value of this noninvasive method in replacing digital subtraction angiography (DSA) in the detection of aneurysms of the circle of Willis in patients with subarachnoid hemorrhage admitted to our institution. METHODS: A helical acquisition was performed for computed tomographic scans obtained for 120 patients with a 1 mm per second table speed and a 1-mm collimation, 1:1 pitch. Axial source images were transferred on a console Advantage Windows workstation (General Electric, Milwaukee, WI) and CTA was obtained using maximum intensity projection reconstruction. All patients had undergone DSA of the circle of Willis (80 patients preoperatively and 40 postoperatively). RESULTS: A total of 129 aneurysms were detected in 107 patients. Three-dimensional CTA disclosed nothing abnormal in 13 patients. Ninety-two patients sustained one aneurysm, 10 patients sustained two, 3 patients sustained three, and 2 patients sustained four. All results were confirmed by DSA. In two cases, aneurysms of the middle cerebral artery were defected by CTA but not by DSA. When using angiographic views, the aneurysm was always masked by a branch of the middle cerebral artery. CONCLUSION: The sensitivity of three-dimensional CTA is comparable with that of DSA, and its specificity is 100%. Because CTA is simple, quick, noninvasive, and reliable, we think that it can eventually replace DSA.

[Modern imaging in cerebral vein angioma]. / L'imagerie moderne dans les angiomes veineux cérébraux.

Cerebral venous angiomas are vascular malformations of the brain which, before the advent of modern imaging, and in particular MRI, were thought to be rare. They have a specific angiographic aspect called "caput Meduse" as it corresponds to the description of a large draining vein to which converge numerous radial veins located in the white matter. These true vascular malformations have characteristic histological features making it possible to differentiate them from other vascular malformations, notably cavernomas. These lesions are less scanty than classically believed, being the most frequent malformations encountered in post-mortem examination series. The circumstances in which cerebral venous angiomas are discovered vary considerably, and haemorrhage can be the revealing sign. Some authors regard these malformations as "abnormalities" of white matter veins and not as pathological entities, since they derive from a change in development during embryogenesis, but this theory is not supported by any anatomical evidence. The same authors attribute the bleeding to an associated cavernoma. Whereas CT enables venous angiomas and possible associated cavernomas to be detected, only repeated MRI explorations performed after the finding of venous angioma and hemorrhage can permit, by analysis of signal changes, to confirm or invalidate the non-pathological theory of the venous malformation and its tendency to bleed. Apart from hemorrhages, since gadolinium is used MRI is the most reliable and least invasive means to diagnose angiomas and to detect associated occult angiographic malformations. For this reason, nowadays only hemorrhages require an angiography in search of an arteriovenous malformation demanding prompt treatment. Moreover, MRI makes it possible to detect angiographically occult malformations.

[An angiographic study of spinal vascularization at the thoracic-lumbar level]. / Etude angiographique de la vascularisation médullaire à l'étage dorso-lombaire.

In this retrospective work based on a series of spinal angiograms performed in the Neuroradiology Department of the Salpêtrière Hospital, Paris, we studied the number of examinations that showed one or several anterior radiculospinal arteries at the thoracolumbar level, as well as their origin at different levels from T6 to L3. Analysis of the whole group of 552 patients showed some deviation from the previously published radio-anatomical papers. This was confirmed and illustrated more clearly by the analysis of a series of 174 cases selected among these 552 patients. This second series was particular in that it featured bilateral catheterization of every artery likely to give off a radiculospinal artery at all levels from T6 to L3, thus providing more reliable statistical data. We found that 48% of the patients had their thoracolumbar blood supply based on two anterior radiculospinal arteries the lowest of which was located at, or lower than, T12, and the second and higher one between T6 and T10. Only 45% of the studies showed a blood supply relying on a single anterior radiculospinal artery which most frequently had its origin at T9. In 7% of the cases the thoracolumbar spinal cord was supplied by 3 anterior radiculospinal arteries. Our results demonstrate the presence of at least two different patterns of spinal cord blood supply at the thoracolumbar level, with a variation in the origin of the anterior radiculospinal arteries. These recent findings may increase the reliability and improve the technique of spinal angiography, especially in difficult cases.

MRI in neurosarcoidosis.

Nine patients with neurological manifestations of sarcoidosis were explored by MRI and, in some cases, CT. The MRI examinations were performed in T1- and T2-weighted spin-echo sequences in all patients, with gadolinium injection in seven. Several non-specific lesions were demonstrated, the most frequent of them showing on T2-weighted sequences as high-intensity signals in the periventricular white matter and the semi-oval centres. Other abnormalities, such as infiltrations of the hypothalamo-pituitary region, granulomatous masses within the brain tissue and meningeal infiltrations, were observed. These findings were in agreement with those found in the literature. Gadolinium injection seems to be important in this pathology, as it demonstrates lesions that are not visible on conventional T1- and T2-weighted spin-echo sequences.

Imaging in the exploration of lumbosacral plexus avulsion. Two cases.

In all cases of post-traumatic sensorimotor deficit in the lower limbs unexplained by another pathology, it is not unreasonable to suspect a nerve root avulsion. Whenever available, MRI seems to be the choice examination as it is not invasive and provides a three-dimensional exploration. On the basis of two new cases and a review of the literature, the authors discuss the value of various imaging methods in this pathology.

Choroid plexus papillomas of the posterior fossa in adults: MR imaging and gadolinium enhancement. Report of four cases and review of the literature.

Four cases of benign choroid plexus papillomas of the posterior fossa in adults are reported: two papillomas developed in the fourth ventricle, one in the cerebellopontine angle, and one extended from the fourth ventricle to the cerebellopontine angle. CT, MRI and surgical findings are described. The MRI characteristics on T1 and T2-weighted sequences are compared with those already published. In three cases the tumour signal observed after gadolinium enhancement was intense and homogeneous. The paramagnetic contrast agent provided direct visualization and better discrimination of papilloma location and extent.

[Subarachnoid rupture of supratentorial dermoid cyst: CT and MRI aspects]. / Rupture sous-arachnoïdienne d'un kyste dermoïde supratentoriel: aspect TDM et IRM.

We report a case of ruptured subarachnoid dermoid cyst which was explored with both CT and MRI. This rare condition results from the accumulation of a large amount of fat with a characteristic aspect at-imaging. Rupture causes fat dissemination in the subarachnoid space. In most cases, CT or MRI can provide sure diagnosis of the tumor and of rupture.

[3D-CT angiography with volume rendering technique in the intracerebral aneurysms]. / Angioscanner des anévrismes intracrâniens en rendu volumique (volume rendering technique).

PURPOSE: Many techniques of 3D reconstruction (MIP, SSD) permit a good evaluation of the circle of Willis in order to detect cerebral aneurysms. More recently, the advent in the clinical practice of a calculation algorithm (VRT) adapted to the workstations for images treatment seems to improve evaluation of the characteristics regarding these aneurysms. MATERIALS AND METHODS: We report 4 cases with cerebral aneurysms studies with CT-angiography using the technique MIP and VRT. RESULTS: The VRT, using the totality of image informations, allows a better understanding than MIP about the intracranial cerebral aneurysms including their constitution and 3D localization. CONCLUSION: The VRT reconstruction permits to obtain quickly good quality and reproductive images, without relationship with threshold.

[Magnetic resonance imaging and the discoid meniscus in children]. / Imagerie par résonance magnétique et ménisque discoïde chez l'enfant.

Discoid meniscus is an uncommon dysplasia generally affecting the lateral meniscus. Its congenital or acquired origin remains a question of debate. We report 5 cases or lateral discoid meniscus in 4 girls and 1 boy, aged from 6 to 11 years. The main clinical signs were snapping knee and pain. The discoid meniscus appeared in MRI as an abnormally large meniscus extending into the joint space. It appeared as a central band giving increased signal in 3 out of 5 cases. The significance of this probably trauma-induced image was uncertain. Surgery confirmed MRI findings in 4 cases in which total resection of the meniscus was performed. No operation was performed in the fifth case.

[Neurological complications of hemophilia in children (author's transl)]. / Les accidents neurologiques de l'hémophilie chez l'enfant.

Although the treatment of hemophilia has greatly improved, the disease is still sometimes responsible for neurological or neurosurgical disorders. Such disorders were observed in the department of Neurosurgery at the "Hopital des ENFANTS MALADES' in twelve hemophiliacs, five of them having antifactor antibodies. Four main points results from this study: 1) A traumatic etiology was found only in one third of the cases. 2) CT Scan is the main investigation since it allows to find out what cases should be operated upon. The ratio of neurosurgical cases varies from one statistic to another from 40% to 70%. 3) The frequency of neurological disorders is correlated with the importance of the deficit in antihemophilic factors, which is usually less than 1%. 4) The death rate in this series was nil. Hemophiliacs without antifactor antibodies should receive a substitutive treatment as soon as possible. However, in hemophiliacs with antifactor antibodies, this treatment should only be given when surgery is required.

[Pulmonary arteriovenous malformation in a bronchoscopy simulating a carcinoid tumour]. / Formation tumorale framboisée à l'endoscopie bronchique simulant une tumeur carcinoïde.

The authors report a case of pulmonary arteriovenous malformation in a 48-year-old man. The bronchoscopy revealed a fragile lingular tumoral formation. The diagnosis was based on the thoracotomy and the histopathological findings. The endoscopic features and the different diagnostic options of pulmonary arteriovenous malformation are discussed.