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The purpose of this article is to describe, with 5 clinical cases, the physiological communications between the inner ear and the subarachnoid spaces (SAS) and present the imaging features with regard to. Therefore we briefly illustrate abnormal communications between SAS and perilymphatic fluids in certain cochlear and internal acoustic meatus (IAM) malformations and their consequences. Imaging features may depict diffusion pathway of bacterial meningitis to membranous labyrinth via the cochlear aqueduct or via the IAM. Rarely, in some patients referred for cochleovestibular symptoms, imaging features may display skull base tumors involving the area of cochlear or vestibular aqueduct aperture. Therefore, in patients referred for cochleovestibular symptoms, MR and CT study should carefully scrutinise not only the IAM but also the aperture of the cochlear and the vestibular aqueducts and the cerebellopontine meninges.

Developmental cysts are the most common retrorectal cystic lesions in adults, occurring mostly in middle-aged women. They are classified as epidermoid cysts, dermoid cysts, enteric cysts (tailgut cysts and cystic rectal duplication), and neurenteric cysts according to their origin and histopathologic features. Although developmental cysts are often asymptomatic, patients may present with symptoms resulting from local mass effect (eg, constipation, rectal fullness, lower abdominal pain, dysuria), with a palpable retrorectal mass at digital rectal examination, or with a complication. Infection with fistulization, bleeding, and malignant degeneration are the major complications of developmental cysts. A well-defined, unilocular or multilocular, thin-walled cystic lesion is the main imaging feature. Uncommonly, a sacral bone defect and calcifications are associated with developmental cysts. The differential diagnosis includes cystic sacrococcygeal teratoma, anterior sacral meningocele, anal duct or gland cyst, necrotic rectal leiomyosarcoma, extraperitoneal adenomucinosis, cystic lymphangioma, pyogenic abscess, neurogenic cyst, and necrotic sacral chordoma. Complete surgical excision is indicated to establish the diagnosis and avoid complications.

Filter placement within the inferior vena cava is performed to prevent pulmonary embolism in patients with contraindications or failure of anticoagulant therapy. Several complications of vena cava filters have been described. However, mechanical complications related to IVC filters may not be of any clinical significance. The purpose of this pictorial essay is to present the imaging features of complications related to inferior vena cava filter placement.

Objective: We used MR angiography to examine and follow up the changes of dissecting aneurysms of the extracranial internal carotid artery (ICA)., Materials and Methods: We retrospectively reviewed the records of 101 consecutive patients with dissecting aneurysms of the extracranial ICA. Twenty patients with 26 spontaneous dissecting aneurysms were followed up with MR angiography every 1-2 years (men, 16; women, four; age range, 28-67 years; mean age, 51 years)., Results: The mean duration of follow-up was 41 months (range, 10-93 months). At MR angiography follow-up, 20 aneurysms did not change, four decreased from their original size by 33-53% (mean, 43%), and two resolved. One patient had an asymptomatic recurrent dissecting aneurysm of the extracranial ICA. Clinically, no patient had a thromboembolic stroke or transient ischemic attack during the follow-up period., Conclusion: MR angiography revealed that dissecting aneurysms of the extracranial ICA remain stable, decrease in size, or resolve--but they do not increase in size.

Diffuse cavernous hemangioma of the rectosigmoid colon (DCHR) is an uncommon disease that affects mainly young adults. As the main symptom is non-specific chronic rectal bleeding, the clinical diagnosis is difficult and often delayed. In this essay, we illustrate the imaging features of DCHR, including plain radiograph, barium enema, CT and MR study, and echoendoscopy. Pitfalls in diagnosis and the role of imaging study in the diagnosis, in the preoperative staging, and in the follow-up of the patients are defined.

Objective: We retrospectively reviewed five pathologically proven cases of diffuse cavernous hemangioma of the rectosigmoid colon to define the MR imaging features of this entity., Conclusion: Diffuse cavernous hemangioma of the rectosigmoid colon is revealed as rectosigmoid wall thickening with high signal intensity on T2-weighted MR images. Such wall thickening is associated with abnormal perirectal fat. The extent of bowel involvement and extrarectal locations are well shown on T2-weighted MR images.