Germ cell tumors (GCTs) occur most frequently in the gonads and are relatively rare in other sites, such as the pineal gland, neurohypophysis, mediastinum, and retroperitoneum. GCTs are thought to originate from primordial germ cells, which migrate to the primitive gonadal glands in the urogenital ridge. Extragonadal GCTs might also originate from these cells when the cells are sequestered during their migration. Pathologic subtypes of GCTs vary, and the prevalence of mixed tumors is high. These factors produce a diversity of radiologic findings and make prospective radiologic diagnosis difficult in many cases. However, similar radiologic findings have been observed in pathologically equivalent tumors in varying sites. Seminomas appear as uniformly solid, lobulated masses with fibrovascular septa that enhance intensely. Nonseminomatous GCTs appear as heterogeneous masses with areas of necrosis, hemorrhage, or cystic degeneration. Fat and calcifications are hallmarks of teratomas, most of which are benign. In immature teratomas, scattered fat and calcification within larger solid components are occasionally seen. These imaging characteristics reflect the pathologic features of each tumor, and histologically similar GCTs at varying sites have similar radiologic features. Knowledge of the pathologic appearances of GCTs and their corresponding radiologic appearances will allow radiologists to diagnose these tumors correctly.

There are many kinds of ovarian tumors and tumorlike conditions that produce estrogen or androgen. Magnetic resonance imaging can demonstrate not only ovarian tumors but also an enlarged uterus with a thick endometrium, even in cases of a clinically latent excess of estrogen. These clinical and indirect imaging findings can aid in the differential diagnosis of ovarian tumors. Granulosa cell tumor and thecoma are well-known estrogen-producing tumors. In pediatric or postmenopausal patients, they manifest as precocious pseudopuberty or postmenopausal bleeding, respectively. Conversely, Sertoli-Leydig cell tumor is representative of hormone-producing tumors that cause virilization. However, there are other functioning ovarian tumors besides the sex cord-stromal tumors. It is well known that metastatic ovarian tumors often have androgen-producing stroma and that mucinous cystadenoma sometimes produces estrogens. Most other ovarian tumors can produce sexual hormones in their stroma. In addition, some endocrinologic abnormalities (eg, polycystic ovary syndrome) also cause virilization.

Diagnosis of injuries to the ligamentous structures of the wrist can be a challenge, particularly when there is involvement of the small, complex structures of the proximal wrist. Recent advances in magnetic resonance (MR) imaging, especially in spatial and contrast resolution, have facilitated more precise visualization of these structures. However, there are a number of pitfalls that may cause difficulty in diagnosis of injuries to the triangular fibrocartilage complex (TFCC), lunotriquetral ligament, and scapholunate ligament. Use of inappropriate MR imaging sequences and MR imaging artifacts may decrease the accuracy of diagnosis of injuries to the TFCC and wrist ligaments, whereas variant anatomy of the proximal wrist structures may mimic disease of the TFCC and wrist ligaments. Knowledge of the detailed anatomy of the wrist, as well as variant patterns of structure morphology and signal intensity, can help differentiate actual disease from normal or variant appearances at assessment with MR imaging.

No abstract

The middle arterial phase imaging with k-space centered at 12.6 sec after the peak aortic enhancement was optimal for detecting HCC and showed diagnostic accuracy equivalent to that of the whole triple arterial phase imaging.

High-resolution MR images of the normal wrist using microscopy coils were superior to those using a conventional surface coil qualitatively and quantitatively. High-resolution MR imaging with a microscopy coil would be a promising method to diagnose TFCC lesions.

The proximal zone of the LTL showed a broad spectrum of normal variations in shape and signal intensity on high-resolution MR images with a microscopy coil.

Purpose: To investigate correlations with ulnar variance and the triangular fibrocartilage complex (TFCC) or cartilage of ulnar side of the wrist on high-resolution MRI with a microscopy coil. Materials and Methods:We reviewed ulnar variance, TFCC, and cartilage of the ulnar side of the wrist in 93 subjects (29 asymptomatic volunteers and 64 patients with suspected TFCC injury) with high-resolution MRI using a 47-mm microscopy surface coil. All MR images were obtained with a 1.5 T scanner. Coronal 2D gradient recalled echo T 2 *-weighted images were used for analysis. For qualitative analysis we measured ulnar variance, TFCC angle, thickness in the central portion of TFCC disc proper, and cartilage thickness of the lunate and the ulnar head on MRI and calculated the correlation coefficient between measured values. We also examined the relationship between ulnar variance and age or sex.Results: High-resolution MR images clearly demonstrated TFCC and cartilage of the wrist and ulnar variance. The mean ulnar variance on MRI was ϩ0.26 mm (range, Ϫ4.59 to ϩ3.71 mm). The mean TFCC angle and TFCC thickness were 23.9°(range, Ϫ4.6 to ϩ54.1°) and 1.11 mm (range, 0.4 to 3.22 mm), respectively. Ulnar variance and TFCC angle were positively correlated (r ϭ 0.84), and ulnar variance and TFCC thickness were negatively correlated (r ϭ Ϫ0.71). However, ulnar variance and lunate or ulnar head cartilage thickness were not significantly correlated. Conclusion:High-resolution MRI with a microscopy coil is a useful tool for evaluating the relationship between ulnar variance and ulnar side structures.