High-resolution magnetic resonance imaging of the knee joint: normal anatomy

Excellent morphologic detail was depicted in thin-section, high-resolution magnetic resonance (MR) images obtained with the use of a solenoid surface coil specifically designed for the knee joint. The multiplanar anatomy of the knee was determined by correlating MR images of six fresh cadavers and 10 normal adult knees with corresponding photographs of cryoplaned specimens and by a cross-referencing multiplanar imaging technique.     

Diagnostic imaging of the normal anatomy of the temporomandibular joint

Computed tomography (CT) and magnetic resonance imaging (MRI) are well established imaging modalities to examine the TMJ. MRI is superior to CT in delineating the morphological architecture of the TMJ, not only in cases of normal anatomy, inflammation or tumors, but also if dysfunction of the TMJ is present. This review article presents anatomy as well as imaging strategies of the TMJ.     

Elbow joint: normal anatomy on MR images

The normal anatomy of the elbow joint in axial, sagittal, and coronal planes was evaluated by comparing 30 magnetic resonance (MR) images of eight healthy volunteers with microtomed cryosections prepared from six cadaver elbows. MR images provided depiction of muscles and tendons, bone marrow, articular cartilage, and neurovascular structures. Cross-referencing of MR images from one plane to another was useful in the evaluation of complicated, obliquely oriented muscle bundles and other soft tissues.     

MR imaging of the scrotum: normal anatomy

High-resolution magnetic resonance (MR) imaging with a surface coil was utilized to evaluate the normal scrotum. Scrotal contents, spermatic canal, and inguinal regions were visualized within the same field of view. Differences in signal intensity in the testis, epididymis, tunica albuginea, fluid, fat, and spermatic cord allowed for clear delineation of these structures in detail. The high contrast and spatial resolution of MR imaging, coupled with the wide field of view and absence of ionizing radiation, make MR imaging well suited for evaluation of the scrotum.     

MR imaging of the prostate gland: normal anatomy

MR images of the male pelvis in 55 subjects were analyzed retrospectively for depiction of the zonal anatomy of the prostate gland as related to different repetition (TR) and echo (TE) times, slice thickness, plane of imaging, chronologic age of the patient, and different magnetic field strengths. With imagers operating at 0.35 and 1.5 T, T2-based tissue-contrast images were needed for the demonstration of the internal anatomy of the prostate gland. The display of zonal anatomy was improved when continuous 0.5-cm slices were used. Evaluating sequential sections, the peripheral, central, and transition zones could be differentiated. The peripheral zone showed higher signal intensity than either the central or transition zone and was discerned in the coronal, sagittal, and transverse planes. The central zone was of low signal intensity and was well displayed in the coronal and sagittal planes. The central zone was seen in 31 of the 32 young men (aged 25-35 years) but in only eight of the 23 older men (aged 40 years and older). The transition zone had intrinsic MR parameters similar to the central zone, and the two could be distinguished from each other only by the knowledge of their respective anatomic location. The low-intensity transition zone blended with the periurethral glands and the preprostatic sphincter. The transition zone was of homogeneous low signal intensity in young men but varied in size and signal intensity in older men. Such a detailed display of the prostate zonal anatomy offers a unique potential for the evaluation of prostatic physiology and disease.     

High-resolution magnetic resonance imaging of the wrist: normal anatomy

Magnetic resonance imaging (MRI) provided adequate depiction of carpal soft tissue structures in normal volunteers, as well as accurate anatomic correlation with cadaveric specimens. Using a high field strength system and surface coil techniques, the intricate anatomy of the wrist was best defined on long TR short TE images. However, from a practical view, T1 weighted images (TR 600 ms, TE 25 ms) were most useful because of short imaging times, satisfactory image quality, and the absence of motion artifacts. The coronal plane provided the clearest definition of important structures. Potential diagnostic limitations exist due to the inability of MRI ot clearly delineate articular cartilage, joint capsules, and small interosseous ligmaents. The presence of intra-articular fluid in both living subjects and cadaveric specimens, however, allowed for fine depiction of these structures on T2 weighted images.     

High-resolution magnetic resonance imaging of the ankle: normal anatomy

An imaging-anatomic correlative study of ankle anatomy based upon six healthy adults and six fresh cadaveric specimens was performed to evaluate the diagnostic capabilities of magnetic resonance imaging (MRI). Optimal pulsing sequences and imaging planes for various structures of interest were established. MRI afforded exquisite depiction of anatomic detail, particularly the diagnostically important collateral ligaments. Limitations in the ability to delineate the joint capsule and articular cartilage were documented, with the former detectable only on T2 weighted images in the presence of synovial fluid.     

Ultrasonography features of the diaphragmatic crura: normal anatomy and its variants

PURPOSE: To report the various US patterns of the diaphragmatic crura and the changes occurring during the different phases of respirations. The diaphragm has two US patterns: the central membranous part appears highly reflective while the posterior, upper and lateral muscular portions are hypoechoic and thick. The crura can sometimes appear quite bulky, which appearance is easy to misinterpret. MATERIAL AND METHODS: We carried out a three-stage work: first we reviewed the US examinations of 23 subjects with a nodular appearance of the posteromedial bundles and studied the changes in thickness during respiration. Second we studied the diaphragmatic crura in 30 subjects aged 18-71 years, 15 men and 15 women. We used a commercially available unit with sector and convex 3.5 MHz probes at baseline and during breath hold and acquired multiple parasagittal and transverse scans. The crura thickness was measured in all patients. Last, we studied the diaphragmatic regions of 10 patients with right pleural effusion and of 8 patients with associated ascites and pleural effusion using 2.0-5.0 MHz convex phased-array transducers. RESULTS: We found focal thickening of the crura in 11 of 23 patients with US findings of diaphragmatic nodules, but only in deep inspiration. The thickening was 1.5-2.2 cm long and maximum thickness was 10 mm. In the other 12 subjects we found 9 small lobules in the right and 3 in the left crus. In the anatomic study, we observed a 3-band appearance of the diaphragmatic crura, probably referable to muscle bundles, in 30 subjects on sagittal images, in 12 on coronal images and in 28 on anterior transverse images. The diaphragmatic crura were identified in 26 subjects only. The left posterior crus was identified in 29 subjects on left coronal images and in 15 on anterior transverse images; it was demonstrated on anterior sagittal images in close proximity to the aorta in only 4 subjects. Right crus thickness, measured on sagittal scans, ranged 3-10 mm in deep inspiration and 1-4 mm in expiration while the left crus was 3-6 mm in inspiration and 1-2 mm in expiration. The length of the right crus, studied in the preaortic portion, ranged from 7 cm in deep inspiration to 9.7 cm in expiration while the left one was 6.5 to 8.8 cm. The right lateral diaphragmatic bundles were seen in 28 subjects only on repeated subcostal oblique scans and the the left ones in 11 subjects only. Finally the thin anterior bundles were shown on parasagittal images in 13 cases in the right side and in 2 in the left. A 2-band appearance of the diaphragm was seen in 10 patients with pleural effusion and in 8 patients with associated ascites. A single band was found only in the tendinous portion of the diaphragm. DISCUSSION AND CONCLUSIONS: US is presently considered the imaging method of choice in the assessment of changes in thickness and length of the diaphragmatic crura. These structures have different US patterns and can sometimes appear quite bulky and thus be easily mistaken for other anatomic or abnormal structures; orthogonal scans may be required for the differential diagnosis.     

Computed tomography of the knee joint: technique of study and normal anatomy

Computed tomography was employed in 100 cases to examine the knee joint, without the use of intraarticular contrast medium administration. For greater resolution, only one leg of the patient was introduced into the gantry, and the limb being examined was immobilized and flexed at 8-10 degrees. Computed tomography clearly demonstrated all the anatomical structures that are of clinical interest such as menisci, cruciate and collateral ligaments, and articular and paraarticular soft tissues and tendons. The exact knowledge of the anatomy in axial view and in the indispensable sagittal and coronal reconstructions is fundamental in the identification of pathological conditions.     

MR imaging of the intraparotid facial nerve: normal anatomy and pathology

Three normal volunteers, 58 normal patients, and three patients with parotid tumors were studied with a 0.3 T permanent-magnet imaging system to directly image the intraparotid facial nerve. On T1-weighted images the nerve appeared as a curvilinear structure of relatively low signal intensity within the fatty, high-signal parotid parenchyma. Its major divisions and branches could be imaged only with specially angled axial scan planes. To verify our observations MR imaging was compared with whole-organ cryomicrotome sections cut at the same angles. Normal variations in the appearance of the nerve and pitfalls in its visualization are discussed. Three cases of parotid tumors, with surgical confirmation of the relationship of the facial nerve to the tumor, are presented. MR is the only imaging technique capable of direct imaging of the facial nerve in the parotid bed: it may assist materially in the surgical management of tumors of the parotid gland.     

Esophageal imaging by MR and CT: study of normal anatomy and neoplasms

In 20 patients with normal esophagi, spin-echo magnetic resonance (MR) imaging was performed to determine the appearance at different pulse sequences and T1 and T2 values. Twelve patients with esophageal carcinoma were also studied by both MR and computed tomography (CT); in ten, there was correlation with surgical and pathologic findings. Both MR and CT showed low accuracy in staging the tumors (40% and 70%, respectively), mainly because of difficulty in detecting tumor invasion through the muscle layer into periesophageal fat. Relatively T1-weighted images (repetition time, 0.5 second; echo time, 28 msec) were best for depiction of both normal esophageal anatomy and esophageal tumors. T1 and T2 measurements varied widely for both normal and abnormal esophagi and thus were not useful in predicting histologic findings.