Anatomy of the temporomandibular joint.

The temporomandibular joint (TMJ), also known as the mandibular joint, is an ellipsoid variety of the right and left synovial joints forming a bicondylar articulation. The common features of the synovial joints exhibited by this joint include a fibrous capsule, a disk, synovial membrane, fluid, and tough adjacent ligaments. Not only is the mandible a single bone but the cranium is also mechanically a single stable component; therefore, the correct terminology for the joint is the craniomandibular articulation. The term temporomandibular joint is misleading and seems to only refer to one side when referring to joint function. Magnetic resonance imaging has been shown to accurately delineate the structures of the TMJ and is the best technique to correlate and compare the TMJ components such as bone, disk, fluid, capsule, and ligaments with autopsy specimens.

CT features of abdominal plasma cell neoplasms.

The aim of this study was to describe the CT features of abdominal plasma cell neoplasms. We reviewed CT imaging findings in 11 patients (seven men, four women; mean age 62 years) with plasma cell neoplasms and abdominal involvement. Helical CT of the entire abdomen and pelvis was performed following intravenous administration of contrast material. Images were analyzed in consensus by two radiologists. Diagnoses were made from biopsy, surgery and/or clinical follow-up findings. Multiple myeloma was found in seven patients and extramedullary plasmacytoma in four patients. All patients with multiple myeloma had multifocal disease with involvement of perirenal space (4/7), retroperitoneal and pelvic lymph nodes (3/7), peritoneum (3/7), liver (2/7), subcutaneous tissues (2/7) and kidney (1/7). In three of the four patients with extramedullary plasmacytoma, a single site was involved, namely stomach, vagina and retroperitoneum. In the fourth patient, a double site of abdominal involvement was observed with rectal and jejunal masses. Plasma cell neoplasm should be considered in the differential diagnosis of single or multiple enhancing masses in the abdomen or pelvis. Abdominal plasma cell neoplasms were most frequently seen as well-defined enhancing masses (10/11).

Ultrasound of the pancreas: update and controversies.

The pancreas is an organ that often presents difficulties for ultrasound exploration due to the interference of abdominal gas in the stomach and duodenum. However, with technical experience and the use of a variety of examination techniques, such as filling the stomach with water or cellulose suspension, changing patient's position, or scanning at different moments of respiration, such as suspended inspiration or expiration, it can be seen in its totality in a high percentage of patients. In our opinion, especially as new technical advances have been incorporated into US equipment (color power Doppler, harmonics, and US pulse inversion) and new contrast agents are available, US can compete with CT in this field. Ultrasound can be as useful as CT in most patients with pancreatitis and pancreatic neoplasms. Furthermore, Endoscopic sonography (ES), as well as intraoperative and laparoscopic techniques, are also excellent for visualizing malignant pancreatic lesions and have a special role in preoperative staging. Finally, US is a good technique to guide fine-needle biopsy of the pancreas and for aspiration of inflammatory fluid collections and abscesses. Although CT has played a major role to date, US is presently the most widely available and economical means to visualize the pancreas.

Mycobacterium genavense infection in AIDS: imaging findings in eight patients.

This retrospective study included eight HIV-positive patients with a M. genavense infection. Seven of these patients had a CT scan of the abdomen and a US examination, whereas one patient with pulmonary symptoms had conventional chest radiographs and thin-section CT scan of the thorax. Multiple large retroperitoneal and mesenteric lymph nodes were demonstrated in seven patients; low-attenuation centers within enlarged nodes were identified in two patients. On CT scans two cases showed circumferential wall thickening of the proximal small bowel with a deep ulceration in one of these patients. Additional findings included focal lesions in the liver (n = 1), spleen (n = 2), splenomegaly (n = 6), and hepatomegaly (n = 4). The CT scans from the thoracic examination demonstrated multiple diffuse nodular infiltrates in both lungs. M. genavense infection should be considered in the differential diagnosis of AIDS patients with CD4 counts below 100 cells/mm3 presenting with abdominal lymphadenopathy, multinodular or homogeneous hepatosplenic enlargement and circumferential thickening of the small bowel wall.

Fire eater's pneumonia: radiographic and CT findings.

Acute aspiration of petroleum by fire eaters can cause a distinct type of chemical pneumonitis known as fire eater's pneumonia that manifests on radiologic studies with unilateral or bilateral lung consolidations, well defined nodules, and pneumatoceles. We report three cases of fire eater's pneumonia that manifested with well-defined cavitary nodules (pneumatoceles) on radiographs and CT. One patient developed a bronchopleural fistula and spontaneous pyopneumothorax. CT is valuable for identifying and localizing complications to guide therapy.

Clear cell sarcoma of the abdominal wall with peritoneal sarcomatosis: CT features.

Clear cell sarcoma, also called malignant melanoma of soft parts, is an uncommon neoplasm that involves tendons or aponeuroses of the lower extremity. The CT features of a clear cell sarcoma arising from the abdominal wall with later peritoneal dissemination are described. Peritoneal sarcomatosis from soft tissue sarcomas is a very rare condition previously unreported in the radiologic literature. Metastases to peritoneal surfaces must therefore be considered a possible site for systemic dissemination of soft tissue sarcomas.

Sclerosing mesenteritis: imaging findings in 17 patients.

OBJECTIVE: The purpose of this study was to evaluate the radiologic findings of sclerosing mesenteritis and to describe certain signs that suggest the diagnosis. CONCLUSION: Sclerosing mesenteritis represents a single disease with two radiologically different variants. In an appropriate clinical setting, radiologic features can suggest the diagnosis, delineate the extent of the process, and prescribe or limit surgical procedures. The "fat ring" sign and the presence of a tumoral pseudocapsule are important findings for the diagnosis of the disease.

MR imaging of benign soft-tissue masses of the foot and ankle.

Approximately 75% of all biopsy-proved soft-tissue masses of the foot and ankle are benign tumors or nontumoral lesions representing a variety of histologic types. In some cases, it may be difficult if not impossible to identify the lesion; however, careful analysis of the magnetic resonance (MR) imaging findings and correlation of these findings with the patient's clinical history can usually suggest a more specific diagnosis, particularly in the most common benign tumors of the foot (e.g., fibromatosis, cavernous hemangioma) and in nonneoplastic soft-tissue lesions such as Morton neuroma, ganglion cyst, and plantar fasciitis. In addition, a specific diagnosis can almost always be made in patients with pigmented villonodular synovitis (PVNS) or giant cell tumor (GCT) of the tendon sheath. The MR imaging appearance of PVNS consists of multiple synovial lesions with low or intermediate signal intensity on T1-weighted images and low signal intensity on T2-weighted and gradient-echo images. GCTs of the tendon sheath usually have areas of low signal intensity on both T1- and T2-weighted images due to the paramagnetic effect of hemosiderin. Awareness and understanding of the underlying pathologic findings in lesions of the foot and ankle aid in MR imaging interpretation.

The normal and pathologic ischiorectal fossa at CT and MR imaging.

A wide spectrum of disease processes involve the ischiorectal fossa, including congenital and developmental lesions; inflammatory, traumatic, and hemorrhagic conditions; primary tumors; and pathologic processes outside the ischiorectal fossa with secondary involvement. Both computed tomography (CT) and magnetic resonance (MR) imaging are useful in the definitive diagnosis of these pathologic conditions, with MR imaging being the modality of choice because of its superior contrast resolution and multiplanar capability. In Gartner duct cyst, both CT and MR imaging demonstrate a well-defined, round mass; in tailgut cyst, CT demonstrates a well-defined retrorectal mass with a solid or cystic appearance. MR imaging in particular plays a major role in the assessment of fistula in ano, infection, and hematoma. Lipoma and pelvic plexiform neurofibroma typically have low attenuation and high signal intensity at CT and MR imaging, respectively. Recurrent rectal tumor appears at both modalities as an irregular soft-tissue mass with or without central necrosis in the presacral space, perineum, or pelvic sidewall. Familiarity with the imaging features and differential diagnoses of various ischiorectal pathologic processes will facilitate prompt, accurate diagnosis and treatment.

Primary Sjögren's syndrome and associated lung disease: CT findings in 50 patients.

OBJECTIVE: We prospectively evaluated the high-resolution CT findings in 50 nonsmoking patients with proven primary Sjögren's syndrome. CONCLUSION: High-resolution CT is a sensitive technique in assessing pulmonary involvement in patients with primary Sjögren's syndrome. Interstitial lung disease and bronchiolar inflammatory changes are common abnormal findings seen on CT scans in primary Sjögren's syndrome.

Mycotic aneurysm of the abdominal aorta: CT finding in three patients.

We present three cases of mycotic aneurysms of the abdominal aorta that were initially diagnosed with computed tomography (CT). The accuracy of CT as the first imaging technique in the diagnosis of this condition is reviewed in light of our results and those reported in the literature.

AIDS-related primary esophageal lymphoma.

AIDS-related primary esophageal lymphoma should be considered in the differential diagnosis of a patient with AIDS who presents with dysphagia and a large ulcerated esophageal mass. Endoscopy is mandatory in those patients to establish a definitive diagnosis and to rule out the possibility of an infectious cause of the mass.

[Tuberculous pancreatic abscess: differential diagnosis and favorable response to medical treatment]. / Absceso tuberculoso pancreático: diagnóstico diferencial y respuesta favorable al tratamiento médico.

Pancreatic tuberculosis is rare and may present differential diagnostic problems, specially with cancer of the pancreas. An immunocompetent patient with a pancreatic tuberculous abscess whose clinical manifestations were epigastric pain and a toxic syndrome of one month of evolution is presented. A cystic mass was detected on computerized axial tomography in the tail of the pancreas suggestive of irresectable carcinoma because of vascular invasion with negative percutaneous cytologic puncture for malignant cells. The patient was surgically treated with no histologic confirmation of malignancy. A second laparotomy was performed at 6 months since spontaneous size reduction, external pancreatic fistula with miliary peritoneal dissemination and biopsy compatible with tuberculous granulomas was found. Staining for resistant acid-alcohol bacilli were always negative. Medical treatment achieved complete disappearance of the pancreatic tumor in one year.

Synovial hemangioma of the knee: MRI findings in two cases.

The findings in two patients with histologically proven synovial hemangioma of the knee are described. Both cases emphasize the typical appearance of this unusual tumor on magnetic resonance imaging. Additional radiologic findings, such as adjacent osseous involvement, are discussed.

Malignant neuroectodermal tumour of the chest wall (Askin tumour): CT and MR findings in eight patients.

Malignant neuroectodermal tumour of the chest wall (Askin tumour) is an uncommon malignant neoplasm affecting young adults. We retrospectively reviewed the clinical and pathological information and radiologic studies in our archives on eight cases of this tumour. All cases were pathologically proven. Plain films, CT scans and radionuclide images were available in all cases. MR images were also available in two patients. Although rare, Askin tumour should be included in the differential diagnosis when a chest wall or thoracic paraspinal mass is identified in a young individual.

CT manifestations of peritoneal leiomyosarcomatosis.

CT findings of six patients with pathologically proved malignant peritoneal disease secondary to leiomyosarcomas were reviewed. Peritoneal implants, hepatic metastases and ascites were found in five, five and two, of the six patients, respectively. Neither lymphadenopathies, diffuse peritoneal mesenteric involvement, nor intralesional calcification were observed. Although infrequent, peritoneal leiomyosarcomatosis should be included in the differential CT diagnosis of carcinomatosis.