CT Arthrography and Virtual Arthroscopy in the Diagnosis of the Anterior Cruciate Ligament and Meniscal Abnormalities of the Knee Joint

Objective

To determine the diagnostic accuracy of CT arthrography and virtual arthroscopy in the diagnosis of anterior cruciate ligament and meniscus pathology.

Materials and Methods

Thirty-eight consecutive patients who underwent CT arthrography and arthroscopy of the knee were included in this study. The ages of the patients ranged from 19 to 52 years and all of the patients were male. Sagittal, coronal, transverse and oblique coronal multiplanar reconstruction images were reformatted from CT arthrography. Virtual arthroscopy was performed from 6 standard views using a volume rendering technique. Three radiologists analyzed the MPR images and two orthopedic surgeons analyzed the virtual arthroscopic images.

Results

The sensitivity and specificity of CT arthrography for the diagnosis of anterior cruciate ligament abnormalities were 87.5%-100% and 93.3-96.7%, respectively, and those for meniscus abnormalities were 91.7%-100% and 98.1%, respectively. The sensitivity and specificity of virtual arthroscopy for the diagnosis of anterior cruciate ligament abnormalities were 87.5% and 83.3-90%, respectively, and those for meniscus abnormalities were 83.3%-87.5% and 96.1-98.1%, respectively.

Conclusion

CT arthrography and virtual arthroscopy showed good diagnostic accuracy for anterior cruciate ligament and meniscal abnormalities.     

Percutaneous needle biopsy of the spine

The purpose of this review article is to provide a brief overview of the recent literature on the two main types of percutaneous biopsy methods done in the spinal column: fine needle aspiration biopsy (FNAB) and core needle biopsy (CNB). FNAB is the process of obtaining a sample of cells and bits of tissue for examination by applying suction through a fine needle attached to a syringe. Core needle biopsy involves extracting a cylindrical sample of tissue using a large, hollow needle. The decision for needle biopsy is a joint effort between the clinician, pathologist, radiologist, surgeon, and patient. Specific techniques and approaches with varying needle systems are described for each spinal region. Percutaneous image-guided spine biopsy is a safe and effective procedure. It is the procedure of choice in definitive diagnosis of pathologic lesions of the spine.     

Effect of joint position and ligament tension on the MR signal intensity of the cruciate ligaments of the knee

Six cadaveric lower extremities were imaged with T1-weighted spin-echo pulse sequences with the knees extended and flexed to 90°. Magnetic resonance signal intensities of the anterior cruciate ligament (ACL) and posterior cruciate ligament (PCL) were compared. Changing from extension to flexion resulted in decreased signal intensity in six of six ACLs and five of six PCLs. Two of the knees were then imaged with and without tension applied to the ACL. Both specimens showed a decrease in signal intensity with tension, followed by an increase in signal intensity with release of the tension. Finally, in three of the limbs the ACL was surgically reconstructed and then imaged with and without tension applied to the tension graft. Signal intensity decreased with tension and increased with release of the tension in all three specimens. Thus, joint position and changes in ligament tension affect the signal intensity of the ACL and PCL, generally resulting in a signal intensity decrease with tension.     

Three-dimensional MR visualization of the intracisternal course of the cranial nerves V-VIII by virtual cisternoscopy

Purpose:
A post-processing protocol for 3D visualization of the cranial nerves V-VIII along their intracisternal course is presented. Material and Methods:
Six healthy volunteers underwent MR imaging (1.5 T) to obtain high-resolution heavily T2-weighted data sets (3DFT CISS) with isotropic voxels (0.5 mm³). The data sets were post-processed by using volume rendering software in order to visualize the intracisternal courses of the cranial nerves V-VIII as well as their root entry zones. The data acquisition and post-processing protocol was then applied in 14 patients with a suspected neural compression syndrome according to the clinical findings as well as cross-sectional images and evaluated with respect to image quality and diagnostic value by two neuroradiologists, using a five-point scale. Results:
Virtual cisternoscopy allowed a comprehensive intracisternal 3D visualization of the affected cranial nerves in 12/14 patients. The mean post-processing time amounted to 13.1/5.6/13.7 min for the cranial nerves V/VI/VII and VIII. The mean score for image quality was 4.2, that for diagnostic value 4.1. 2D and/or 3D reference images were indispensable for appreciating the spatial information provided by virtual cisternoscopy. Conclusion:
The data acquisition and post-processing protocol presented here allows comprehensive and standardized intracisternal 3D visualization of the cranial nerves V-VIII in a routine setting as a complementary imaging procedure.     

Immediate postgadolinium spoiled gradient-echo MRI for evaluating the abdominal aorta in the setting of abdominal MR examination

To assess the reproducibility and image quality of immediate postgadolinium chelate spoiled gradient-echo MRI in demonstrating disease of the abdominal aorta. All patients (27 patients: 21 men, 6 women) with substantial disease of the abdominal aorta, who underwent abdominal MR examinations at 1.5 T between 1991 and 1995, were entered in the study. Patients were referred for evaluation of suspected aortic disease (14 patients) or other abdominal diseases (13 patients). Three experienced investigators manually measured luminal and external aortic wall diameters and rated image quality, definition of inner and outer walls, extent of disease, and presence of other abdominal abnormalities, in an independent fashion. A cardiovascular surgeon then rated all studies to determine whether clinical management could be based on the MR findings alone. There was 98 to 99% agreement in measurements of luminal and external wall diameter between the three investigators. Overall image quality was rated as good in 77.8 to 88.9% of patients. A total of 31 additional nonaortic abdominal abnormalities were detected by all observers. The cardiovascular surgeon rated 25 of 27 studies as adequate to determine clinical management based on MR findings alone. Immediate postgadolinium spoiled gradient-echo MRI is a reproducible technique for the demonstration of abdominal aortic disease and possesses good image quality. Advantages of this technique include simultaneous evaluation of other nonvascular diseases of the abdomen, short examination time, and easy implementation as part of routine abdominal MRI scanning protocol.     

Localized proton MR spectroscopy of the brain in children

Small-voxel (3.0–8.0 cm³), magnetic resonance (MR) imaging–guided proton MR spectroscopy was performed in 54 patients (aged 6 days to 19 years) with intracranial masses (n = 16), neurodegenerative disorders (n = 34), and other neurologic diseases (n = 4) and in 23 age-matched control subjects without brain disease. A combined short TE (18 msec) stimulatedecho acquisition mode (STEAM) and long TE (135 and/or 270 msec) spin-echo point-resolved spatially localized spectroscopy (PRESS) protocol, using designed radio-frequency pulses, was performed at 1.5 T. STEAM spectra revealed short T2 and/or strongly coupled metabolites; prominent resonances were obtained from N-acetyl aspartate (NAA), choline-containing compounds (Cho), and total creatine (tCr). Lactate was well resolved with the long TE PRESS sequence. Intracranial tumors were readily differentiated from cerebrospinal fluid (CSF) collections. All tumors showed low NAA, high Cho, and reduced tCr levels. Neurodegenerative disorders showed low or absent NAA levels and enhanced mobile lipid, glutamate and glutamine, and inositol levels, consistent with neuronal loss, gliosis, demyelination, and amino acid neuro-toxicity. Preliminary experience indicates that proton MR spectroscopy can contribute in the evaluation of central nervous system abnormalities of infants and children.     

MR imaging of disorders of the brachial plexus

The authors evaluated 64 consecutive patients with suspected brachial plexus (BP) abnormalities of diverse cause with magnetic resonance (MR) imaging, using the body coil and a standardized protocol. Of the 43 patients for whom follow-up was available, 25 were suspected of having neoplastic involvement of the BP, nine had sustained injuries, and nine presented with BP symptoms of uncertain cause. MR imaging was 63% sensitive, 100% specific, and 77% accurate in demonstrating the abnormality in this diverse patient population. When patients with neoplastic and traumatic disorders were considered separately, sensitivity increased to 81%, accuracy to 88%, and specificity remained unchanged. In the patients with a clinical diagnosis of idiopathic or viral plexitis, the MR imaging findings were normal, serving to exclude other structural abnormalities. It is concluded that MR imaging is valuable in the assessment of a wide range of BP disorders.     

Interventional procedures in the upper urinary tract

The introduction and acceptance of percutaneous nephrostomy as a safe and effective alternative to surgical nephrostomy served as the impetus for the development and expansion of an ever-increasing number of techniques that are encompassed by the term “interventional uroradiology.” This article reviews many of the non-vascular interventional techniques that have proliferated during the past decade and that are currently used in the kidney, ureter, and perinephric space. The authors emphasize those procedures that are most frequently employed, as well as their own preferences and perspectives on these procedures.     

Evaluation of the cervical spine in the obtunded patient

Assessment of cervical spine stability in the posttraumatic obtunded patient can be difficult to accomplish with currently available imaging modalities. Dynamic fluoroscopy during passive flexion and extension has been proposed by some authors as a method for the evaluation of cervical spine stability. We present our experience with dynamic fluoroscopy, the general opinions of multiple trauma centers, and alternative methods for evaluating cervical spine stability in the obtunded patient. The potential risks and problems associated with each method are discussed.     

Trauma of the chest

Trauma to the chest may cause a wide range of injuries including fractures of the thoracic skeleton, contusion or laceration of pulmonary parenchyma, damage to the tracheobronchial tree, diaphragmatic rupture or cardiac contusion. Conditions affecting primarily extrathoracic sites may have indirect effects on the lungs causing adult respiratory distress syndrome or fat embolism. Laceration of the aorta is the typical and likewise most life threatening complication of massive blunt chest trauma necessitating immediate diagnosis and repair.Conventional radiography rather than cross-sectional imaging is the mainstay in diagnosing thoracic trauma. During the critical phase with often concomitant shock, pelvic and spinal injuries tailored radiographic views or even upright chest radiographs are impractical. The severely traumatized patient is usually radiographed in the supine position and suboptimal roentgenograms may have to be accepted for several reasons. It is well documented that many abnormalities detected on CT were not apparent on conventional radiographs, but CT is reserved for hemodynamical stable patients. Nevertheless certain situations like aortic rupture require further evaluation by CT and aortography.The value of conventional radiography, CT, MRI and aortography in chest trauma is reviewed and typical radiographic findings are presented.     

Some borderlands of the cervical spine

The complexity of the structure of the cervical spine as well superimposition by the parts of adjacent vertebrae, as well as other structures may cause some abnormalities to be overlooked. Among those abnormalities are, the short sagittal diameter, neoplasm in the cancellous part of the vertebral bodies, spurs in the apophyseal joints, trauma, infection and others.     

MRI of the post-discectomy lumbar spine

Laminectomy and discectomy are common procedures in the management of symptomatic lumbar disc herniation. Complications of such surgery include recurrent/residual disc herniation, epidural scar formation, discitis, arachnoiditis and pseudo-meningocele. Gadolinium-enhanced MRI is the technique of choice for investigating recurrent symptoms following discectomy. This article reviews the normal early and late post-laminectomy MR appearances, as well as the pathological findings associated with the above-mentioned complications.     

MR imaging characteristics of noncancerous lesions of the prostate.

Radical prostatectomy specimens from 53 men with clinical stage A or B prostate cancer were retrospectively reviewed and compared with correlative axial T2-weighted magnetic resonance (MR) images obtained just before surgery. Non-cancerous lesions were evaluated for signal intensity and location. Focal high-signal-intensity areas (n = 72) were present in 81% of patients. The 26% of lesions seen in the central gland all correlated with cystic atrophy. Of the 53 lesions seen in the peripheral prostate, 47 (89%) were cystic atrophy without associated cancer, four (7.5%) cystic atrophy with cancer, and two (3.8%) focal inflammation. Focal low-signal-intensity areas (n = 42) were present in 60% of patients. Of the 31% of lesions in the central prostate, one-fifth correlated with benign prostatic hyperplasia (BPH) and four-fifths with fibrous tissue. Of the 69% of peripheral lesions, 83% corresponded to fibrous tissue, 10% to BPH, and 7% to normal tissue. Mixed lesions (n = 42) were present in 64% of patients; 86% of these were located centrally and 14% peripherally. All mixed central lesions were BPH; the peripheral lesions were areas of combined cystic atrophy and fibrosis. BPH of low or mixed signal intensity can extend into the peripheral prostate and mimic cancer. High-intensity cystic atrophy associated with cancer can mimic normal tissue.     

Lymphoepithelial cyst of the pancreas: radiological and pathological findings

We report a case of a rare lymphoepithelial cyst of the body of the pancreas that developed in a woman complaining of constipation for 15 years. Ultrasonography revealed a homogeneous isoechoic lesion, while CT demonstrated a polycystic homogeneous mass with central scar and calcification. Cytological investigation of a CT-guided biopsy permitted diagnosis of lymphoepithelial cyst. The patient was operated on and had an uneventful recovery. The histological finding was of a cyst wall lined with keratinised squamous epithelium surrounded by lymphoid tissue with reactive follicular hyperplasia. The radiological findings and differential diagnosis are discussed. Correspondence to: D. Regge     

Three-dimensional steady-state MR angiography of the lower extremities

Volume steady-state black-blood magnetic resonance imaging was evaluated as a method for depicting lower extremity vasculature. In steady-state imaging, flow has low signal intensity because motion destroys the coherence of transverse magnetization. To optimize image contrast, computations and measurements were obtained for the three-dimensional (3D) GRASS (gradient-recalled acquisition in the steady state) and 3D SSFP (steady-state free precession) sequences and a range of TRs and flip angles to determine optimal vessel-muscle contrast. The best results were achieved with a 3D GRASS sequence with a TR msec/TE msec of 25/5 and a flip angle of 30°. Coronal images of the femoral and popliteal vessels were obtained in healthy volunteers with various fields of view and voxel sizes. Inflow of unsaturated spins from outside the image region, yielding high signal intensity, could be a potential drawback in steady-state black-blood imaging; however, problems can be avoided by using coronal acquisitions and large fields of view. Steady-state black-blood imaging depicts vessels with high accuracy and is faster and free of flow artifacts.     

CT and US of the pancreas

The diagnostic capabilities of pancreatic imaging continue to improve with technological advancements in computed tomography (CT), ultrasound (US), and magnetic resonance imaging (MRI). To update the practicing radiologist, this article summarizes the current literature on pancreatic imaging, with particular emphasis on CT and US. Pertinent clinical considerations of the disease entities are included, along with illustrative material from the authors' experience.     

Flow pattern analysis in the abdominal aorta with velocity-encoded cine MR imaging

The sites of deposition of atherosclerotic plaque on the aortic wall are considered to be influenced by secondary and retrograde flow patterns that cause regions of altered shear stress. To detect secondary flow patterns and areas of retrograde flow in the abdominal aorta, velocity-encoded cine (VEC) magnetic resonance (MR) imaging was performed at five different levels of the abdominal aorta in nine healthy volunteers. Net retrograde flow (expressed as a percentage of antegrade flow) increased from proximal to distal levels and was maximal (13.8% ± 11.8) just distal to the origin of the renal arteries. An increase in the duration of retrograde flow over the cardiac cycle was observed from proximal to distal levels. Whereas retrograde flow was present at end systole and early diastole in each volunteer at every level, the duration and amount of retrograde flow during diastole showed high interindividual variation. Such differences suggest the possibility of variable vascular geometric risk factors in the population for the development of atherosclerotic plaque. The location of retrograde flow in the abdominal aorta demonstrated in vivo with VEC MR imaging was close to that obtained with in vitro flow visualization studies in models of the abdominal aorta.     

Fast spin-echo imaging of the temporomandibular joint

The applicability of a fast spin-echo (PSE) technique for magnetic resonance imaging of the tem-poromandibular joint (TMJ) was studied, and the technique compared with a conventional spin-echo (CSE) technique. Sagittal Tl-weighted CSE and dual-echo FSE images of 50 TMJs in 25 patients with symptoms of internal TMJ derangement were compared. CSE and FSE images were diagnostically comparable in 22 TMJs (44%). The FSE technique was rated better than CSE imaging for delineation of the disk in 26 joints (52%), whereas the CSE technique was rated better in only two joints (4%). The FSE technique was preferred overall in 54% of the joints. Mild to moderate joint effusion was detected in 17 joints because additional T2-weighted data were provided with the dual-echo FSE technique. The study showed that FSE imaging is an effective technique for evaluation of the TMJ. It is faster and diagnostically comparable to or better than CSE imaging, with the added advantage of providing T2-weighted data.     

Left femoral vein approach for the percutaneous placement of the Bird's Nest Filter

The Bird's Nest Filter femoral catheter set has proven to be too short in some patients to permit placement in close proximity to the renal veins via the left femoral vein approach. The use of the longer, but otherwise identical Bird's Nest Filter jugular catheter set via the left femoral vein eliminates this problem.     

产前超声预警征象对胎儿主动脉缩窄的诊断价值

目的 探讨产前超声诊断预警征象对胎儿主动脉缩窄(COA)的诊断价值.资料与方法 回顾性分析21例COA胎儿的临床及影像学资料,根据随访与产前诊断结果分为真阳性组及假阳性组,比较两组胎儿临床资料、超声图像及相关测量参数.结果 真阳性组10例,假阳性组11例,真阳性率为47.6％.真阳性组与假阳性组胎儿首次诊断孕周[(25...