Comparison of Imaging Diagnosis of Pyo genic Abscess and Inflammatory Cancer in the Breast: Focused on MRI

PURPOSE: To compare the radiologic findings of pyogenic abscess(PA) and inflammatory cancer(IC) of the breast, as seen on mammograms, US, and MR images and to evaluate the usefulness of the differential diagnostic findings of MRI for differentiation of PA and IC of the breast. MATERIALS AND METHODS: We retrospectively analyzed the mammographic, US and MR findings of nine histopathologically proven cases of PA and four cases of IC of the breast. Parenchymal density, mass density, skin thickening and calcification were evaluated by mammography, and the extent of lesion and its morphologic characteristics and changes of dermal lymphatics by US and MRI. The latter was also used to analyse signal intensity and enhancement pattern. RESULTS: Mammographic findings for both lesions were nonspecific. US showed that the pyogenic abscess was a hypoechoic and anechoic complex lesion with posterior acoustic enhancement, while inflammatory cancer was a spiculated lesion with a heterogeneous hypoechoic echotexture. On 3D-GRE dynamic enhanced M-RI, PA was shown in six cases(66.7 %) to be a lesion with superficial periareolar involvement, in contrast to the deep parenchymal spread seen in all cases of IC. A central non- enhanced portion with an irregular thick peripheral enhanced rim was seen in eight cases of PA(88.9 %) , and in all cases of IC an inhomogeneously enhanced spiculated lesion in parenchyma and a diffusely enhanced dermal and subcutaneous layer was apparent. An MRI time-intensity curve showed that the enhancement pattern was slow in five cases of PA(55.6 % ) and irregular in four(44.4 %), while for IC it was rapid in three cases(33.3 %) and irregular in one(11.1 % ). CONCLUSION: As compared with mammography and US, 3D-GRE dynamic MRI was a useful method for the differential diagnosis of PA and IC of the breast. The characteristic MR findings of PA were a central non-enhanced portion with an irregularly thick peripheral enhanced rim, located mainly in the superficial periareloar area and spreading into the parenchymal layer. An inhomogeneously enhanced spiculated solid mass in the parenchyma associated with diffuse dermal thickening and lymphatic dilatation was more suggestive of IC.

MR Assessment of Distribution and Amount of Joint Effusion in Patients with Traumatic Knee Joint Disorders

PURPOSE: To clarify the distribution of joint effusion, and the relationship between type of injury andamount of joint effusion seen in traumatic knee joint magnetic resonance imaging (MRI). MATERIALS AND METHODS: Weretrospectively reviewed the MR images of 400 patients with traumatic knee joint effusion. The knee joint spacewas divided into four compartments: central portion (para-ACL, para-PCL), suprapatellar pouch, posterior femoralrecess, and subpopliteal recess, and we then compared the amount and distribution of effusion. For statisticalanalysis, the chi-square test was used. RESULTS: Among 400 MRI examinations of joint effusion, 383 knees (96%)showed homogeneous low intensity on T1-weighted images, and - except for ten cases of fluid-fluid levels-homogeneous high intensity on T2-weighted images. Knee joint effusion was clearly shown to be distributed mainlyin the suprapatellar pouch (345, 86%), followed by the central posterior femoral recess, and the subpoplitealrecess (p<0.001). Extensive joint effusion was less frequently found in the normal group, but was occasionallyfound in the combined injury group (p<0.001). The relationship between amount of joint effusion and type ofinjury was statistically significant (p<0.001), except in the case of medial and lateral collateral ligamentinjury. CONCLUSIONS: The distribution of joint effusion in patients with traumatic knee disorders is a reflectionof anatomic communication, and whether the amount of joint effusion was small or large depended on the anatomicallocation and type of injury.