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Biomedical subjects

P M Som

Publications and source records attributed to P M Som.

At least 19 recordsLinked to original sources
PubMed1992

Central nodal necrosis and extracapsular neoplastic spread in cervical lymph nodes: MR imaging versus CT.

Computed tomographic (CT) scans and magnetic resonance (MR) images obtained in 24 patients with cervical lymphadenopathy were retrospectively and blindly evaluated by two readers for the presence of central nodal necrosis (CNN) and extracapsular nodal spread (ENS). The CT studies were all enhanced, and the MR images were obtained with short repetition time (TR)/echo time (TE), long TR/double echo, and enhanced short TR/TE fat-suppressed sequences. Each MR imaging sequence was interpreted separately and then collectively. Sixty lymph nodes were identified with CT. Sensitivity for CNN was 16%-67% with the unenhanced MR pulse sequences, 50% with enhanced sequences, and 83%-100% with CT. The most accurate reading of MR images for CNN was with the unenhanced T1-weighted and T2-weighted images (86%-87%); the accuracy of CT was 91%-96%. The accuracy of MR imaging for detecting ENS was maximal with T1-weighted images (78%-90%). Gadolinium-enhanced, fat-suppressed images did not improve accuracy in evaluating CNN or ENS. CT is currently more accurate than unenhanced or enhanced MR imaging in detecting CNN or ENS.

Carcinoma, Squamous Cell↗
PubMed1992

Detection of metastasis in cervical lymph nodes: CT and MR criteria and differential diagnosis.

Radiologists are frequently asked to evaluate cervical lymph nodes with CT or MR imaging to determine if metastases are present, how extensive the metastases are, and if they have spread from lymph nodes to critical adjacent structures such as the carotid artery and skull base. Accurate information of this type is essential if the most appropriate treatment is to be selected. The purpose of this report is to review the diagnostic criteria that are currently used with CT and MR imaging to diagnose metastases in cervical nodes by evaluating nodal size, shape, grouping, and necrosis and extranodal tumor spread. In addition, emphasis is placed on details that should be included in the CT and MR report, such as the location of the nodes, the presence of nodal calcification, and the presence of associated diseases such as parotid cysts that may suggest a specific diagnosis like HIV infection. Because optimal treatment planning depends on the combined information gleaned from the clinical evaluation and the imaging studies, it is essential that there be a close dialogue between clinicians and radiologists.

Carcinoma, Squamous Cell↗
PubMed1991

Lesions that manifest as medial cheek and nasolabial fold masses.

Seventeen cases were collected in which the patient presented with a medial cheek or nasolabial fold mass. Most of these lesions were uncommon, and some were rare. The most reliable differentiating finding was the type of associated bone involvement. The malignancies had bone erosion and as a group could be distinguished from the other masses. Computed tomographic attenuation and magnetic resonance imaging signal intensities were nonspecific and did not allow a definitive diagnosis to be made. The types of pathologic conditions and their sectional imaging findings are reviewed.

Cheek↗
PubMed1991

Simulated aggressive skull base erosion in response to benign sinonasal disease.

Benign sinonasal masses and slow-growing neoplasms tend to remodel the nasal vault and facial bones, and this is particularly true of nasal polyps and inverted papillomas. However, when such benign masses press against the floor of the anterior cranial fossa and the walls of the sphenoid sinuses, simulated aggressive bone destruction rather than bone remodeling usually occurs. This type of bone destruction implies to the radiologist that a carcinoma may also be present, and this information could dissuade a surgeon from operating with an attempt at cure. In fact, about 90% of the time with inverted papillomas and in virtually all cases of nasal polyposis, no carcinoma is present. The computed tomographic (CT) scans and magnetic resonance images of 14 patients are used to demonstrate these changes. In addition, the CT scans of three patients with malignancies are shown to illustrate the similarity in the bony skull base changes.

Diagnosis, Differential↗
PubMed1991

Hemangioma of the nasal vault: MR and CT features.

Six patients with a history of epistaxis (five patients) or nasal obstruction (one patient) were found to have a capillary hemangioma of the nasal vault that involved one or more nasal turbinates. Four patients underwent computed tomographic (CT) examination; two of these also underwent magnetic resonance (MR) imaging. Four others underwent only MR imaging. At CT and MR, all of the lesions were well circumscribed and intensely enhancing, with contralateral deviation of the nasal septum. Remodeling of the surrounding bone was present in three patients. On T1-weighted MR images, the masses were intermediate in signal intensity. Varying degrees of T2 shortening were shown on T2-weighted MR images, with an appearance that suggested the presence of blood products surrounding an inner matrix of higher-signal-intensity tumor. Intense enhancement at CT and MR assisted differentiation of tumor from retained sinonasal secretions. In two patients, external carotid arteriography revealed small foci of pooling contrast material; in one of these patients, arteriovenous shunting was also present. Pathologic examination in all patients demonstrated capillary hemangiomas with varying degrees of fibrosis and hemosiderin deposition.

Adult↗
PubMed1990

Calcified sphenoid mucocele.

Sphenoid sinus mucoceles are uncommon lesions, and may rarely contain calcifications within their wall. We describe a new appearance of this lesion--sphenoid sinus mucocele with gross calcifications within its matrix.

Aged↗
PubMed1990

Multiple intracranial mucoceles associated with phaeohyphomycosis of the paranasal sinuses.

The purpose of this article is to alert clinicians to a new pathogenic fungus of the paranasal sinuses called Exserohilum rostratum. Exserohilum species are one of the etiologic agents of phaeohyphomycosis, a constellation of entities caused by dematiaceous fungi. This class of fungal sinus infection has emerged only in the past decade; it occurs primarily in immunocompetent individuals and produces a tenacious, progressive pansinusitis. To our knowledge, this study describes the first case of multiple intracranial mucoceles secondary to E rostratum. The diagnostic workup includes computed tomography and magnetic resonance imaging followed by direct microscopic examination of tissue biopsy specimens. A craniotomy followed by a bilateral external ethmoidectomy was necessary for complete extirpation of the infected mucoceles. Aggressive surgical management of this mycotic infection is described.

Adult↗
PubMed1990

Streaming hypointensity in hemorrhagic glioblastoma multiforme. An illustrative case.

The computed tomography, the magnetic resonance and the angiographic features of a patient with the unusual findings of multicentric intraparenchymal, subependymal and intraventricular hemorrhage in association with glioblastoma multiforme are presented. The utility of MR in demonstrating an irregular, streaming pattern of hypointensity within the lesion (and thereby suggesting an underlying neoplasm) is briefly discussed.

Brain↗
PubMed1990

Perineural tumor extension through the foramen ovale: evaluation with MR imaging.

Perineural tumor extension is a form of metastatic disease in which primary tumors spread along neural pathways and gain access to non-contiguous regions. The treatment and prognosis are altered when perineural extension occurs. Awareness and proper evaluation are critical for the radiologist. The third (mandibular) division of the trigeminal nerve (V3), passing through the skull base via the foramen ovale, is a common route of perineural spread of head and neck lesions. Seven patients with perineural tumor involvement of the mandibular nerve were evaluated with magnetic resonance imaging with use of standard spin-echo pulse sequences emphasizing T1-weighted information. Three patients had adenoid cystic carcinoma, three had squamous cell carcinoma, and one had well-differentiated lymphocytic lymphoma of the orbit. MR imaging signs of perineural involvement included smooth thickening of V3, concentric expansion of the foramen ovale, replacement of the normal trigeminal cistern hypointensity by an isointense mass, lateral bulging of cavernous sinus dural membranes, and atrophy of masticator muscles.

Carcinoma, Adenoid Cystic↗
PubMed1990

Hypointense MR signal in chronically inspissated sinonasal secretions.

Six patients with chronically obstructed sinuses were examined with computed tomography (CT) and magnetic resonance (MR) imaging prior to surgical decompression. In all six patients, hypointense signal was present on all MR sequences despite CT evidence of the presence of high-attenuation material filling the sinus. At surgery, all specimens were viscid or pastelike with no evidence of hemorrhagic products as a cause for the MR findings. Sinonasal secretions may have a spectrum of MR signal intensity, ranging from hyperintense to signal void with all pulse sequences. These findings must be kept in mind when interpreting images of patients with suspected chronic sinusitis.

Adult↗
PubMed1990

Hypointense paranasal sinus foci: differential diagnosis with MR imaging and relation to CT findings.

Despite the plethora of information provided by magnetic resonance (MR) imaging that allows differentiation of some substances that are indistinguishable at computed tomography (CT), there are diagnostic problems. In particular, there are several quite disparate substances that all appear as either low signal intensity or signal void on T1-weighted images and even lower signal intensity or signal void on T2-weighted images. These substances include air, desiccated secretion, mycetomas, acute hemorrhage, calcium, bone, and enamel. When they are surrounded by material that has long T1 and T2 relaxation times, a not uncommon MR appearance in the sinonasal cavities, they may be impossible to differentiate from one another. The current explanations for the low signal intensities are presented, the similarities in the MR appearance are illustrated, and the use of CT to resolve diagnostic problems is discussed. CT appears to be the best modality for initially examining patients with suspected routine inflammatory disease or fungal infection.

Aspergillosis↗
PubMed1989

Lingual osteoma.

The 29th patient with a lingual osteoma is presented. This is the first case, to our knowledge, with preoperative radiographic and computed tomographic documentation. This rare, benign tumor almost always occurs as a pedunculated solitary mass that arises from the posterior tongue near the foramen cecum. The patients are usually young women who complain wf dysphagia or fullness in the base of the tongue. The imaging findings and theories of the origin of this tumor are described.

Adult↗
PubMed1989

Chronically obstructed sinonasal secretions: observations on T1 and T2 shortening.

Clinically assessed chronic proteinacious sinonasal secretions usually have long T1 and T2 relaxation times reflecting their high water content. However, in some cases variable combinations of short and long T1 and T2 relaxation times are found. To study the causes of these findings, the magnetic resonance (MR) images of 41 patients with surgically proved, chronically obstructed sinonasal secretions were studied. The relative signal intensities on both T1- and T2-weighted sequences of the sinus specimens were correlated with the gross viscosity of the specimens at surgery. Ten specimens were collected that were not contaminated with either blood or saline. UV spectrophotometric analysis of four of these samples excluded the presence of methemoglobin. Total protein content was determined in five samples, and in vitro T1 and T2 values were measured in one sample. These T1 and T2 relaxation times were accurately predicted with use of a standard pure lysozyme protein solution with the same concentration as the specimen. In addition, the observed T1- and T2-weighted signal intensities on the 41 MR images were predicted from an analysis of pure protein solutions. This study concludes that the primary causes of the variable T1 and T2 relaxation times of chronic sinonasal secretions are the macromolecular protein concentration, the amount of free water, and the specimen viscosity. Furthermore, an orderly and predictable transition of these signal intensities occurs over time.

Chronic Disease↗
PubMed1989

Benign and malignant sinonasal lesions with intracranial extension: differentiation with MR imaging.

Most sinonasal lesions that extend into the anterior cranial fossa are malignant tumors. However, benign inflammatory polypoid disease can also rarely be manifested in this manner. Fourteen surgically proved cases of such benign and malignant disease were studied with magnetic resonance (MR) imaging. The appearances of the benign and the malignant lesions were quite different and allowed the seven chronic polypoid lesions to be distinguished from the tumors. The benign lesions had nonhomogeneous appearances on MR images due primarily to varying degrees of free-water resorption and protein concentration. The tumors had primarily homogeneous low-to-intermediate signal intensities due to their highly cellular composition.

Carcinoma, Squamous Cell↗
PubMed1989

High-grade malignancies of the parotid gland: identification with MR imaging.

Most tumors in the parotid gland are either benign neoplasms or low-grade malignancies. The magnetic resonance (MR) images of 29 patients with such tumors were reviewed. These masses typically have low T1-weighted and high T2-weighted signal intensities and have clearly defined margins. The signal characteristics presumably reflect the serous and mucinous products that are characteristic of these lesions. The MR images of six patients with aggressive parotid tumors were reviewed and correlated with operative and pathologic findings. These high-grade parotid lesions are uncommon, usually have poorly defined margins, and have low T1- and T2-weighted signal intensities. These signal characteristics presumably reflect the lack of serous and mucinous products, the high mitotic ratio, and the high nuclear to cytoplasmic ratios that are characteristic of these lesions. The authors conclude that the findings of these tumors on MR images are characteristic and should be suggestive of their diagnosis. The preoperative diagnosis of these high-grade tumors allows a more radical surgical treatment to be well planned before surgery. The primary differential diagnoses of these aggressive tumors with MR imaging include fibrosis and sialolithiasis.

Humans↗