Foramen tympanicum or foramen of Huschke: anatomical cone beam CT study

Objective

The foramen of Huschke (foramen tympanicum) represents a developmental defect in the antero-inferior aspect of the bony external auditory meatus. The foramen is located at the antero-inferior aspect of the external auditory canal, posteromedial to the temporomandibular joint. The aim of this study is to define the prevalence and location of the foramen of Huschke.

Methods

We retrospectively examined 207 cone beam CT (CBCT) studies (414 ears). We used flat panel detector (FPD)-based CBCT (New Tom FP; Quantitative Radiology, Verona, Italy) for imaging in our department. We noted the location of the foramen tympanicum and calculated its prevalence as a percentage.

Results

We found a foramen tympanicum in 37 (17.9%) of 207 patients. This was unilateral in 24 patients (11.6%) and bilateral in 13 patients (6.3%). Mean axial diameter was 5 mm and mean sagittal diameter was 2 mm.

Conclusion

The foramen tympanicum is an uncommon disorder and is well demonstrated on CBCT. This is the first study to detect the foramen tympanicum using FPD-based CBCT.     

Jugular foramen: anatomic and computed tomographic study

The computed tomographic (CT) appearance of the jugular foramen was examined in detail, and anatomic and CT sections were correlated. The pars nervosa and pars vascularis were identified, and, with intravenous contrast enhancement, a rapid sequence of scans at a gantry angle of +30 degrees to the canthomeatal line demonstrated cranial nerves IX, X, and XI. The osseous margins of the jugular foramen were best shown by CT at planes of sections parallel and positive (0 degrees - 30 degrees) of the canthomeatal line. CT can be used to evaluate osseous anatomy and the jugular foramen with precision sufficient to confidently exclude an intracanalicular mass.     

The bicipital groove: radiographic, anatomic, and pathologic study

By using patient radiographs and pathologic specimens, the bicipital groove of the humerus was studied to determine the normal configuration and common abnormalities of this region. Factors analyzed in evaluating the bicipital groove included the medial wall angle, depth and width of the intertubercular sulcus, and presence or absence of bony spurs arising from the floor or medial wall of the groove. The supratubercular ridge was observed as an osseous protuberance in about one-half of the population; it does not seem to be of pathologic significance. A specific radiographic projection is described, which allows evaluation of the bicipital groove.     

Postoperative anatomic and pathologic findings at CT following gastrectomy.

Helical computed tomography (CT) is useful in identifying postoperative anatomic changes, complications, and tumor recurrence in gastric cancer patients who have undergone gastrectomy. Postoperative anatomic changes can usually be identified on consecutive CT scans. Complications include anastomotic leakage, duodenal stump leakage, intraabdominal bleeding, wound complications, and other less common complications (postoperative pancreatitis, retention of surgical foreign bodies, diffuse peritonitis). The degree and extent of bowel wall thickening is important in diagnosing tumor recurrence; however, CT lacks specificity. Large or conglomerated lymph node metastases can be easily diagnosed at CT; however, small solitary or focal metastases may not be detected or differentiated from nonmetastatic nodes. Ascites, a common finding with peritoneal seeding in gastrointestinal tumors, is well depicted at CT. Hematogenous metastases from gastric carcinoma are most frequently seen in the liver and are best demonstrated with helical CT performed during the portal venous phase of enhancement (sensitivity >90% for the detection of lesions >1 cm). The sophisticated surgical procedures used in gastrectomy can alter normal anatomy and make image interpretation difficult; thus, familiarity with the appearance of postoperative anatomic changes, complications, and tumor recurrence is essential for accurate CT evaluation of affected patients.     

The diaphragm: anatomic, pathologic, and radiologic considerations

The diaphragm, by virtue of its complex anatomy and multiple ligamentous connections to both thoracic and abdominal structures, is more than a simple partition between the chest and abdomen. Cross sectional images of the diaphragm and peridiaphragmatic processes can be confusing unless the radiologist is aware of the normal structure of the diaphragm, its attachments to the body wall, and the multiple ligaments that attach to the diaphragm.     

Orbital apex: correlative anatomic and CT study

A detailed analysis of the coronal anatomic and CT appearances of the orbital apex is presented. In cadavers, coronal CT 9800 scans of the orbital apex and precisely corresponding cryomicrotomic sections were obtained. The CT appearance of the optic nerve, anulus of Zinn, and cranial nerves III-VI at the superior orbital fissure and orbital apex were determined. These anatomic structures were also demonstrated in clinical CT studies. Practical applications of the anatomic landmarks in evaluating orbital apex tumors are illustrated.     

Selective arteriography of glomus tympanicum and jugulare tumors: techniques, normal and pathologic arterial anatomy

Glomus tympanicum and jugulare tumors arise within the middle ear and jugular fossa, respectively, but often extend into the adjacent areas of the skull base and posterior fossa. Multiple branches of the external carotid, internal carotid, and vertebral arteries may contribute to the vascular supply of these lesions. The arteriograms of 15 patients with glomus tumors were correlated with the surgical findings to determine if selective arteriography could define precisely the involvement within the middle ear, jugular fossa, and mastoid. The arteriographic mapping correlated well with the surgical findings in nine of 13 cases that had surgery, but a few important limitations were found. Therefore, a new arteriographic projection, called a transcanalicular view, is proposed that separates the middle ear from the jugular fossa, allowing for better visualization and assessment of the tumor blush.     

Volume-rendered 3D CT of the mesenteric vasculature: normal anatomy, anatomic variants, and pathologic conditions.

Multi-detector row computed tomography (CT) offers important advantages over more conventional imaging methods in the evaluation of the mesenteric vasculature. It allows faster scanning, which practically eliminates motion and breathing artifacts, as well as thinner collimation. These advances, coupled with rapid intravenous administration of contrast material, allow excellent opacification of the mesenteric arteries and veins. This improves the quality of the three-dimensional (3D) data sets, which in turn leads to improved 3D vascular maps and more accurate assessment of various conditions such as arterial or venous encasement in patients with pancreatic cancer, mesenteric ischemia, or inflammatory bowel disease. Three-dimensional multi-detector row CT also allows better visualization of arterial and venous branching, thereby improving detection of more distal vascular involvement. In addition, 3D multi-detector row CT may help detect hemodynamic changes in patients with active inflammation and hyperemia of a bowel segment because it can be used to measure bowel wall enhancement over time. Carcinoid tumors that have infiltrated the mesentery have a characteristic CT appearance, and other conditions such as lymphoma or sclerosing mesenteritis can also manifest as an infiltrating mass that envelops mesenteric vessels. Three-dimensional multi-detector row CT represents a significant advance in CT technology and can help ensure prompt, accurate evaluation of the mesenteric vasculature.     

Chronic submasseteric abscess: anatomic,radiologic, and pathologic features

Herein we present five cases of submasseteric abscess that most commonly occurred in patients with a history dental disease. CT has been the main imaging method for diagnosing lesions in the masticator space and adjacent to the mandible; however, we found that, in some of our cases, CT defined the lesion poorly or not at all. In some cases, MR imaging defined the lesion better. Radiologic manifestations of this condition and pathologic correlations are discussed.     

Primary retroperitoneal neoplasms: CT and MR imaging findings with anatomic and pathologic diagnostic clues.

Primary retroperitoneal neoplasms are a rare but diverse group of benign and malignant tumors that arise within the retroperitoneal space but outside the major organs in this space. Although computed tomography and magnetic resonance imaging can demonstrate important characteristics of these tumors, diagnosis is often challenging for radiologists. Diagnostic challenges include precise localization of the lesion, determination of the extent of invasion, and characterization of the specific pathologic type. The first step is to determine whether the tumor is located within the retroperitoneal space. Displacement of normal anatomic structures of the retroperitoneum is helpful in this regard. For tumors that are located within the retroperitoneum, the next step is to identify the organ of origin. Specific signs, including the "beak sign," the "embedded organ sign," and the "phantom (invisible) organ sign," are useful for this purpose. When there is no definite sign that suggests the organ of origin, the diagnosis of a primary retroperitoneal tumor becomes likely. Awareness of specific patterns of spread, specific tumor components, and tumor vascularity help in further narrowing the differential diagnosis. Attention to these diagnostic clues is essential in making an accurate radiologic diagnosis of primary retroperitoneal tumors and in obtaining clinically significant information. Copyright RSNA, 2003.     

CT and anatomic study of postcatheterization hematomas.

The appearance of hematomas resulting from transfemoral catheterization as depicted with computed tomography (CT) has been infrequently reported. The authors devised a system for classifying the CT appearance of such iatrogenic hematomas that is based on the anatomic location and route of bleeding. There are four different types of hematomas: retroperitoneal, intraperitoneal, groin and thigh, and abdominal wall. Bleeding spreads along the fascial planes, and the type of hematoma probably depends on whether the bleeding is confined to the femoral sheath or spreads into the femoral triangle. Recognition of the different types is essential as they may have different clinical implications.     

Left infrarenal region: anatomic variants, pathologic conditions, and diagnostic pitfalls

Computed tomography (CT) is the preferred method for evaluating the left periaortic infrarenal region. Structures larger than 11 mm in cross-sectional diameter in this region are considered abnormal and should be evaluated for lymphadenopathy, hydroureter, or a vascular abnormality such as venous thrombosis or varicoceles. Normal structures include inferior mesenteric vessels, left gonadal vein and artery, and ureter. The diagnostic process may be complicated by variations in anatomy, including double inferior vena cava, left inferior vena cava, retroaortic left renal vein, circumaortic left renal vein, horseshoe kidney, crossed-fused renal ectopia, renal agenesis, and ureteral duplication. Familiarity with the anatomy of this region and awareness of normal variants are necessary to avoid errors in diagnosis. Radiologists should also be aware of problems in CT technique (nonopacified bowel, dynamic and unenhanced scanning) that can confuse the diagnosis.     

Bridging septa of the perinephric space: anatomic, pathologic, and diagnostic considerations

The perinephric space is not a simple fat-filled chamber through which fluid may be distributed unhindered. It is divided into multiple compartments by fibrous lamellae, the bridging septa. Some of these structures arise from the renal capsule and extend to the perinephric fascia; others are attached only to the renal capsule and are arranged more or less parallel to the renal surface. Still others connect the anterior to the posterior leaves of the perinephric fascia. The resulting compartments exert an important influence on pathologic processes, resulting, for example, in limitation of the spread of pus and tamponade of bleeding points. The configuration of many perinephric collections can only be understood by knowledge of the existence and arrangement of these lamellae. The current criteria for differentiation of subcapsular from perinephric hematomas are shown to be in error, and a new sign for such differentiation is described. There are also implications regarding therapeutic drainage of perinephric abscesses, particularly by the percutaneous route. A new classification of the perinephric fascia is proposed.     

Computed tomography of the larynx: correlation with anatomic and pathologic studies in cases of laryngeal carcinoma

High-resolution real-time ultrasonography of the lumbosacral spine was performed in 10 control patients and in six patients with suspected spinal dysraphism. The spinal cord was readily visualized in both groups. Lack of ossification of the posterior arch of the spine in normal infants and the presence of a bony defect in patients with spina bifida permit sonographic investigation of the spinal canal and its contents. It is concluded that the diagnosis of spinal cord tethering can be established rapidly by high-resolution real-time ultrasonography, which may be used in screening patients with suspected occult spinal dysraphism.     

Elastofibroma dorsi: CT, MR and pathologic study in a new case.

As reported before elastofibroma dorsi is a rare benign tumor of elastic connective tissue with typical clinical and suggestive radiological features. We evaluated the CT and MR characteristics of this periscapular lesion in a new case, before and after contrast enhancement, and tried to determine in how far the nature and extent of the tumor can be predicted.