Frequency and spectrum of abnormalities in the bone marrow of the wrist: MR imaging findings

Objective. To describe the frequency of marrow abnormalities on wrist MR imaging and the MR findings of these various abnormalities. Design and patients. Five hundred and nineteen patients were studied at 1.5 T. Two observers recorded the presence and location of avascular necrosis, occult fractures and arthritic edema [focal osteoarthritis, ulnolunate abutment, rheumatoid arthritis, septic arthritis, gouty arthritis and scapholunate advanced collapse (SLAC)]. Results and conclusion. One hundred and eighty-seven (36%) patients demonstrated marrow abnormalities in the wrist, of which 101 were diagnosed as arthritis [64 (34%) as focal osteoarthritis, 17 (9%) as ulnolunate abutment, 15 (8%) as rheumatoid arthritis, 2 as septic arthritis, 2 as SLAC, and 1 as gouty arthritis]. Seventy-two patients had occult fractures and in 27 patients avascular necrosis was seen. MR imaging can reveal various abnormalities in bone marrow of the wrist when findings on radiography are normal or equivocal. Received: 29 May 1998 Revision requested: 8 July 1998 Revision received: 8 December 1998 Accepted: 22 January 1999     

High-resolution surface-coil MR of cortical lesions in medically refractory epilepsy: a prospective study.

PURPOSETo determine the role of surface-coil MR imaging in evaluating medically refractory neocortical partial epilepsy.METHODSA prospective study of 25 patients with medically refractory neocortical partial epilepsy was performed. Head- and surface-coil images were reviewed by two neuroradiologists to determine the clarity with which cortical lesions were depicted. The ability of imaging, combined with surface electroencephalography (EEG), to locate the suspected epileptogenic zone was evaluated.RESULTSCompared with head-coil studies, surface-coil studies showed four more lesions, caused the most probable diagnosis to be altered in five patients, and better defined the lesions in four patients. Of 11 patients with lobar EEG abnormalities, imaging showed focal cortical abnormalities within the same or adjacent lobe in five and multifocal abnormalities in two. Of six patients with EEG abnormalities restricted to two adjacent lobes, imaging showed focal cortical abnormalities in one of these lobes in five patients and multifocal abnormalities in one patient. Of eight patients with a nonfocal EEG, imaging showed focal cortical abnormalities in five and multifocal cortical abnormalities in one. In two of 13 patients, video/EEG telemetry improved seizure location whereas surface-coil imaging showed focal cortical lesions in six and provided relevant prognostic information in five.CONCLUSIONCompared with head-coil studies, surface-coil imaging of the cerebral cortex improved detection and differentiation of focal cortical lesions in 64% of patients. Video/EEG telemetry improved location in 15% of patients, and surface-coil imaging combined with EEG results provided improved location of the suspected epileptogenic zone or relevant prognostic information in 85%.     

MR arthrography of the hip: normal intra-articular structures and common disorders

This pictorial review illustrates the anatomical features of normal intra-articular components of the hip and their common disorders on MR arthrography. On T1-weighted MR arthrograms, the normal contrast-filled joint cavity shows a homogeneous high signal intensity. Normal acetabular labrum appears as a well-delineated triangle showing a low signal intensity, surrounded by contrast material in the perilabral recess. Intra-articular paramagnetic contrast outlines labral tears, loose bodies, communicating labral cysts and cartilage lesions (traumatic tears, focal defects, degenerative fissures and thinning), and improves their detection. Overall, MR arthrography enables accurate detection and staging of hip intra-articular structure abnormalities. Received: 6 June 1998; Revision received: 2 January 1999; Accepted: 2 April 1999     

The use of positron emission tomography in the clinical assessment of epilepsy

Positron emission tomography (PET) of local cerebral glucose utilization is highly sensitive in detecting epileptogenic regions that correspond to electrographic localization in patients with epilepsy. In medically refractory temporal lobe epilepsy for which surgical resection of the epileptogenic zone is a therapeutic option, the application of PET enables more than 50% of adults and older children to be successfully operated on without the necessity for chronic intracranial electrographic monitoring. In infants with intractable infantile spasms and various types of partial epilepsy, PET has uncovered focal areas of cortical dysplasia and other anatomic abnormalities, which, after resection, have resulted in cessation of seizures and developmental improvement. The distribution of PET abnormality is in excellent agreement with the extent of the epileptogenic zone as determined by intraoperative electrocorticography, thus avoiding the necessity for chronic intracranial electrographic monitoring in 90% of these infants. As a result of PET, the preoperative evaluation of intractable epilepsy in both adults and children has become less invasive and less costly.     

Cerebrospinal fluid cleft with cortical dimple: MR imaging marker for focal cortical dysgenesis

PURPOSE: To determine whether the magnetic resonance (MR) imaging feature of a cerebrospinal fluid (CSF) cleft and cortical dimple can be used as a marker for cortical dysgenesis. MATERIALS AND METHODS: MR images in 875 patients with epilepsy were evaluated for the following features of focal cortical dysgenesis: cortical thickening, indistinct junction between gray and white matter, macrogyria, and abnormal sulcal pattern. Images with these features were reevaluated to determine the relationship between the CSF cleft-cortical dimple complex and focal cortical dysgenesis and its contribution to diagnosis. The cleft-dimple complex was defined as a prominent CSF space associated with a region of cortical volume loss adjacent to the dysgenesis. RESULTS: Seventy-one patients had cortical dysgenesis, including 27 with cellular proliferation abnormalities, 18 with migration abnormalities, 25 with cortical organization abnormalities, and one with miscellaneous anomalies. Histologic correlation was available in 20 patients. There was an associated cortical dimple in 29 (41%) patients. This association was strongest in patients with cortical organization abnormalities: It was present in 22 of the 25 (88%) patients. In 12 (48%) patients with abnormalities of cortical organization, the CSF cleft was easier to detect than other features of cortical dysgenesis or contributed directly to the MR imaging diagnosis. CONCLUSION: The cleft-dimple complex is a marker for subtle cases of focal cortical dysgenesis and may be due to maldevelopment. In patients with seizures, the presence of a cleft-dimple complex should alert the physician to scrutinize adjacent regions for developmental anomalies.     

18 F-FDG PET显像对致痫灶的定位诊断价值

目的　探讨 18F -脱氧葡萄糖 (FDG)PET显像对癫痫灶的定位诊断价值。方法　难治性癫痫患者 2 2例 ,男 15例 ,女 7例 ,平均年龄 19.0岁 ,平均病程 8.2年。所有患者均进行常规 18F -FDGPET显像 ,结合脑电图 (EEG)及MRI、CT对 2 1例患者进行开颅手术 ,术中在皮层脑电图 (EcoG)监测下行致痫灶切除术 ,并送病理学检查 ;另 1例进行立体定向杏仁、海马损毁术。所有患者术后随访疗效。结果　 2 2例癫痫患者中 ,2 1例 18F -FDGPET显像阳性 (95 .5 % ) ,2 0例表现为发作间期低代谢灶 ,1例为发作期高代谢灶 ;EEG检查阳性 17例 (77.3 % ) ,其中 8例无定位意义 ;CT、MRI阳性者 5例 (2 2 .7% ) ;18F -FDGPET定位的致痫灶与EcoG一致的有 18例 (85 .7% ) ,不完全一致的 2例 ,不一致的 1例 ;18F -FDGPET显像阳性 19例中 ,18例手术病理异常 (94.7% ) ,PET阴性的 1例手术病理为正常脑组织 ;开颅手术治疗后 ,癫痫发作完全消失者 9例 (4 2 .9% ) ,癫痫发作次数减少 5 0 %以上者 9例 (4 2 .9% ) ,发作次数无明显变化 3例 (14 .3 % ) ;另 1例进行立体定向杏仁海马损毁术的患者癫痫发作次数无明显变化。结论　18F -FDGPET显像对致痫灶的定位诊断灵敏、准确 ,对指导癫痫外科手术有重要的临床价值     

Computertomographische Ergebnisse bei Kindern mit Cerebralen Anfällen

Summary A total of 228 children suffering from seizure disorders were investigated by means of cranial computerized tomography (CT). Their age ranged from 3 weeks to 15 years. Structural abnormalities were assessed in 63% of these cases. The greatest incidence of organic abnormalities occurred in children with major epilepsy (83%) and with focal seizures (71%). Clinical data and the course of illness may require additional angiographic and repeated CT investigations.     

Magnetic resonance and cranial ultrasound characteristics of periventricular white matter abnormalities in newborn infants

OBJECTIVE: To characterize the range of abnormalities within the periventricular white matter (PVWM) in a cohort of newborns using magnetic resonance (MR) brain imaging and to compare the focal MR abnormalities with the cranial ultrasound (CUS) findings. METHODS: Retrospective study of MR brain and CUS findings of infants born in the 18-month period 1998-1999. PVWM abnormalities were identified by MR and focal lesions were characterized by size, number and distribution using a grading scale. Correspondence with CUS findings was assessed. RESULTS: 175 MR examinations corresponding to n = 105 preterm infants, (median GA 28, range 23-36 weeks) and n = 25 term infants (median GA 39, range 37-42 weeks) were analysed for PVWM abnormalities. In the preterm group, MR demonstrated a normal PVWM in n = 76, focal areas of altered signal intensity (SI) in PVWM in n = 26 and venous infarction in n = 3. In the term group, MR demonstrated a normal PVWM in n = 15, focal areas of altered SI in PVWM in n = 4, oedematous PVWM in n = 2 and a middle cerebral artery infarction in n = 4. All infants with normal MR had normal CUS findings. A focal PVWM SI abnormality detectable on MR corresponded with an abnormality on CUS in only n = 10/30. CONCLUSIONS: MR appears considerably more sensitive than CUS in demonstrating the existence and extent of focal PVWM lesions in newborn infants. Satisfactory correspondence between the two imaging investigations is obtained only for cystic PVWM lesions.     

The value of interictal brain SPECT in epilepsy patients without mesial-temporal sclerosis

PURPOSE: Most of the literature concerning interictal SPECT brain scanning in patients with seizures has involved the evaluation of those with temporal lobe epilepsy. The authors' aim was to determine the utility of interictal SPECT in patients with neocortical epilepsy. MATERIALS AND METHODS: Eighty-four patients with neocortical epilepsy were evaluated with 95 interictal SPECT scans and magnetic resonance imaging (MRI). RESULTS: Fifty-four percent of studies with normal MRI findings had SPECT images without regions of hypoperfusion. Sixty-one percent of patients with abnormal MRI results had matching defects visible on SPECT images. Fourteen scans (only 24%) had focal hypoperfusion by SPECT and no obvious matching MRI finding. CONCLUSIONS: Interictal SPECT, without a comparison ictal study, is of potentially limited value in localizing neocortical seizure foci. SPECT findings usually match MRI findings. Interictal SPECT, however, may still be of value in confirming abnormalities detected by ictal examination.     

Recurrent pyogenic cholangitis: comparison between MR cholangiography and direct cholangiography

PURPOSE: To compare the accuracy of magnetic resonance (MR) cholangiography with that of direct cholangiography for the evaluation of recurrent pyogenic cholangitis. MATERIALS AND METHODS: Twenty-four patients with recurrent pyogenic cholangitis underwent MR cholangiography before surgery, and 18 of these 24 also underwent direct cholangiography. Two reviewers evaluated MR cholangiograms and direct cholangiograms and focused on identifying intrahepatic ductal dilatation, stricture, and calculi, as well as coexistent parenchymal abnormalities, on the basis of the classification of the internal lobes and segments of the liver. These observations were compared with surgical findings. RESULTS: According to examination results in the surgical specimens, 24 patients had 46 segmental abnormalities. MR cholangiography depicted all 46 (100%) segments with ductal dilatation, 22 (96%) of 23 segments with focal ductal stricture, and 43 (98%) of 44 segments with ductal calculi. Eighteen patients who underwent direct cholangiography had 32 segmental abnormalities according to examination results in the surgical specimens. Direct cholangiography depicted 15 (47%) of 32 segments with ductal dilatation, eight (44%) of 18 segments with focal ductal stricture, and 14 (45%) of 31 segments with ductal calculi. CONCLUSION: MR cholangiography is superior to direct cholangiography for accurate topographic evaluation of recurrent pyogenic cholangitis because it is able to depict all of the biliary tree, despite obstruction or stenosis.     

Carotid canal dehiscence in the human skull

Abnormalities of the floor of the carotid canal have been studied in 538 skulls. These abnormalities range from a fissure to total absence of the floor. This variation may be caused by abnormalities of the internal carotid artery or deficiencies in ossification of the skull base. CT suggests that these changes should be taken into account by surgeons working on the skull base. Received: 19 June 1998 Accepted: 14 October 1998     

Focal cortical dysplasias: MR imaging,histopathologic, and clinical correlations in surgically treated patients with epilepsy

BACKGROUND AND PURPOSE: Focal cortical dysplasia (FCD) covers a spectrum of conditions in which the neuropathologic and electroclinic presentations and the surgical outcomes vary. The aim of this study was to identify the MR features of histologic subtypes of FCD that would be useful for differential diagnosis. METHODS: We reviewed the MR data of 49 patients treated surgically for intractable partial epilepsy, who received a histologic diagnosis of FCD not associated with other brain abnormalities except hippocampal sclerosis and who were classified by histologic criteria as having architectural dysplasia (28 patients), cytoarchitectural dysplasia (six patients), or Taylor's FCD (15 patients). RESULTS: From the MR features, it was generally possible to distinguish Taylor's FCD from architectural or cytoarchitectural dysplasias (non-Taylor's FCD). Findings suggesting Taylor's FCD were focal cortical thickening, blurring of the gray-white matter junction, and hyperintensity (on T2-weighted images) of subcortical white matter often tapering toward the ventricle. Focal brain hypoplasia with shrinkage and moderate signal intensity alterations in the white matter core were present in most patients with architectural dysplasia. The lesion was generally extratemporal in Taylor's FCD and temporal in architectural dysplasia. Ipsilateral hippocampal sclerosis was often present in architectural dysplasia (dual abnormality). CONCLUSIONS: In patients with FCD, Taylor's FCD and non-Taylor's FCD can usually be distinguished with MR imaging, although some overlap exists. A provisional MR diagnosis is important for presurgical investigations and surgical planning and may have prognostic implications.     

Changes in the blood-labyrinth barrier. Assessments by magnetic resonance

PURPOSE: Recent progress in magnetic resonance imaging (MRI), with contrast-enhanced and steady-state sequences, allows fine depiction of labyrinth abnormalities related to neoplastic, inflammatory, ischemic, degenerative or traumatic disorders. We examined 488 patients with sensorineural hearing loss, vertigo or dizziness, but normal CT findings, to evaluate MR capabilities in showing labyrinth conditions. MATERIAL AND METHODS: January 1994 to May 1998, four hundred and eighty-eight patients with labyrinthine symptoms were submitted to CT. Sixty-eight of them, with normal CT findings, were also examined with MRI, which was performed using quadrature head or surface coils and a single dose (0.1 mmol/kg) Gd-DTPA administration. Conventional T1 and T2 high resolution SE images were acquired. The labyrinth was studied of 52 patients with normal CT findings and no abnormalities in the cerebello-pontine angle or internal auditory canal. RESULTS: Fourteen of 52 patients (27%) exhibited labyrinth enhancement from tumor (5%), hemorrhage (3%), infection (15%), surgical (2%) or radiosurgical (2%) procedures. GRASS sequences allowed differentiation of mass lesions (e.g., tumors, clots) from other conditions. CONCLUSION: Generally the labyrinth exhibits no contrast enhancement even after a triple Gd-DTPA dose. In inflammatory conditions, enhancement is not always diffuse, as expected, but may be focal. Spontaneous hemorrhages can account for labyrinth enhancement. In neoplastic conditions, enhancement may persist for as many as 6 months, and a mass effect against labyrinthine fluids may appear on GRASS images. Although there are no reports on labyrinthine degeneration after radiation therapy, one of our patients submitted to irradiation 7 years previously, had focal bilateral cochlear enhancement, which suggested a correlation with previous treatment.     

Magnetic resonance imaging of epilepsy at 3 Tesla

Patients with epilepsy often have a structural cause for their seizures and may benefit from surgical resection. As recommended in the National Institute of Health and Clinical Excellence (NICE) guidelines, magnetic resonance imaging (MRI) is used to screen for structural abnormalities in these patients and there is increasing evidence that 3T MRI has better sensitivity and specificity than 1.5T. This article reviews the imaging findings of many of the common diseases that can cause epilepsy.     

High-resolution magnetic resonance imaging of the anal sphincter using a dedicated endoanal receiver coil

The use of a surface coil in MR imaging improves signal-to-noise ratio of adjacent tissues of interest. We therefore devised an endoanal receiver coil for imaging the anal sphincter. The probe is solid and re-usable: it comprises a saddle geometry receiver with integral tuning, matching and decoupling. It is placed in the anal canal and immobilised externally. Both in vitro and in vivo normal anatomy is identified. The mucosa is high signal intensity, the submucosa low signal intensity, the internal sphincter uniformly high signal intensity and the external sphincter low signal intensity on T1- and T2-weighted images. In females, the transverse perineal muscle bridges the inferior part of the external sphincter anteriorly. In perianal sepsis, collections and the site of the endoanal opening are identified. In early-onset fecal incontinence following obstetric trauma/surgery, focal sphincter defects are demonstrated; in late-onset fecal incontinence external sphincter atrophy is seen. In fecally incontinent patients with scleroderma, forward deviation of the anterior sphincter musculature with descent of rectal air and feces into the anal canal is noted. The extent of sphincter invasion is assessed in low rectal tumours. In children with congenital anorectal anomalies, abnormalities of the muscle components are defined using smaller-diameter coils. Such information is invaluable in the assessment and surgical planning of patients with a variety of anorectal pathologies. Received: 17 March 1998; Revision received: 19 May 1998; Accepted: 27 May 1998     

Comparison of a conventional cardiac-triggered dual spin-echo and a fast STIR sequence in detection of spinal cord lesions in multiple sclerosis

The current optimal imaging protocol in spinal cord MR imaging in patients with multiple sclerosis includes a long TR conventional spin-echo (CSE) sequence, requiring long acquisition times. Using short tau inversion recovery fast spin-echo (fast STIR) sequences both acquisition time can be shortened and sensitivity in the detection of multiple sclerosis (MS) abnormalities can be increased. This study compares both sequences for the potential to detect both focal and diffuse spinal abnormalities. Spinal cords of 5 volunteers and 20 MS patients were studied at 1.0 T. Magnetic resonance imaging included cardiac-gated sagittal dual-echo CSE and a cardiac-gated fast STIR sequence. Images were scored regarding number, size, and location of focal lesions, diffuse abnormalities and presence/hindrance of artifacts by two experienced radiologists. Examinations were scored as being definitely normal, indeterminate, or definitely abnormal. Interobserver agreement regarding focal lesions was higher for CSE (ϰ = 0.67) than for fast STIR (ϰ = 0.57) but did not differ significantly. Of all focal lesions scored in consensus, 47 % were scored on both sequences, 31 % were only detected by fast STIR, and 22 % only by dual-echo CSE (n. s.). Interobserver agreement for diffuse abnormalities was lower with fast STIR (ϰ = 0.48) than dual-echo CSE (ϰ = 0.65; n. s.). After consensus, fast STIR showed in 10 patients diffuse abnormalities and dual-echo CSE in 3. After consensus, in 19 of 20 patients dual-echo CSE scans were considered as definitely abnormal compared with 17 for fast STIR. The fast STIR sequence is a useful adjunct to dual-echo CSE in detecting focal abnormalities and is helpful in detecting diffuse MS abnormalities in the spinal cord. Due to the frequent occurrence of artifacts and the lower observer concordance, fast STIR cannot be used alone. Received: 9 September 1999; Revised: 14 December 1999; Accepted: 16 December 1999     

Foreign-body granuloma of the kidney: CT, MR and pathologic correlation

The differential diagnosis of renal masses containing fatty foci is limited to a small number of well-defined tumors, angiomyolipoma being the most frequent. In recent years clear cell carcinomas with intratumoral fatty foci have been reported, due to either entrapment of local fat or to regressive adipose metaplasia. Demonstration of focal calcifications is a valuable sign, being relatively common in carcinomas while rare in more benign lesions. We report a case of a foreign-body granuloma of the kidney, containing both calcifications and foci of fat. The value of this case, in our opinion, is that it demonstrates that detection of the previously mentioned features in a renal mass does not necessarily imply a presumptive diagnosis of renal cell carcinoma. Received: 11 June 1998; Revision received: 3 November 1998; Accepted: 23 November 1998     

Transient globus pallidus T 1 shortening associated with polycythaemia and dystonia

We report a child who concurrently developed polycythaemia, dystonia, and T 1 shortening in the globus pallidus, medial cerebral peduncle and superior cerebellar peduncles on MRI. With spontaneous resolution of the polycythaemia after about 2¹/₂ years, the dystonia and MRI abnormalities also resolved. Although the physiological cause of the T 1 shortening is not known, this appears to be another cause of T 1 shortening in the basal ganglia. Received: 1 June 1998 Accepted: 11 August 1998     

Focal liver lesions: Doppler ultrasound

Echo patterns of focal liver lesions as well as other morphological criteria do not suffice for differential diagnosis. In an attempt to increase the specificity of ultrasound of focal liver lesions, several years of Doppler-flow information was evaluated. Recent advances in ultrasound technology (power Doppler imaging, second harmonic imaging) as well as commercial availability of an intravenous signal enhancer (contrast agent) have additionally improved results of this technique. Received: 9 January 1998; Revision received: 18 May 1998; Accepted: 14 July 1998     

Epilepsy.

As surgical treatments for adult and pediatric forms of epilepsy have become more refined, methods for noninvasive localization of epileptogenic foci have become increasingly important. Detection of focal brain metabolic or flow abnormalities is now well recognized as an essential step in the presurgical evaluation of many patients with epilepsy. Positron emission tomography (PET) scanning is most beneficial when used in the context of the total clinical evaluation of patients, including scalp EEG, invasive EEG, neuropsychologic testing, etc. Metabolic PET studies also give insight into pathophysiologic mechanisms of epilepsy. The dynamic nature of the interictal hypometabolism observed with 18[F]FDG in some patients suggests that excitatory or inhibitory neurotransmitters and their receptors may be involved. An exciting current application of PET scanning is the use of tracers for neurotransmitter receptors in the study of epilepsy patients. Mu and non-mu opiate receptors have been extensively studied and are beginning to give new insights into this disorder. Increased labeling of mu receptors in temporal neocortex using 11C-carfentanil has been demonstrated and, in some patients, supplements the clinical localization information from 18[F]FDG studies. Increased mu opiate receptor number or affinity is thought to play a role in anticonvulsant mechanisms. Specificity of increased mu receptors is supported by the absence of significant changes in non-mu opiate receptors. Other brain receptors are also of interest for future studies, particularly those for excitatory neurotransmitters. Combined studies of flow, metabolism, and neuroreceptors may elucidate the factors responsible for initiation and termination of seizures, thus improving patient treatment.