Alexander S. Mark

Magnetic resonance imaging of the TMJ disc in asymptomatic volunteers

Forty-two temporomandibular joints (TMJs) in 21 asymptomatic volunteers were visualized by magnetic resonance imaging (MRI). The subjects, 12 males and nine females, were between 23 and 43 years of age and had no history of TMJ pain, joint noise, limited opening, or previous treatment for TMJ disorder. A cephalometric head-holder was designed to position the TMJ in an accurate and reproducible manner and multisection parasagittal images were obtained perpendicular to the longitudinal axis of the condyle. MR images depicted anterior disc position in 32% of the asymptomatic joints (8/24 males, 5/18 females). Anterior disc position in asymptomatic subjects may be a predisposing factor to TMJ dysfunction or simply an anatomic variant whose prevalence must be considered when evaluating TMJ dysfunction.

Labyrinthine Enhancement on Gadolinium-Enhanced Magnetic Resonance Imaging in Sudden Deafness and Vertigo: Correlation with Audiologic and Electronystagmographic Studies

Sudden deafness with or without vertigo presents a difficult diagnostic problem. This article describes 12 patients with enhancement of the cochlea and/or vestibule on gadolinium–diethylenetriamine pentaacetic acid–enhanced magnetic resonance imaging (MRI), correlating the enhancement with the auditory and vestibular function. All patients were studied with T2-weighted axial images taken through the whole brain, enhanced 3-mm axial T1-weighted images taken through the temporal bone, and enhanced T1-weighted sagittal images taken through the whole brain. Cochlear enhancement on the side of hearing loss was found in all the patients. The vestibular enhancement correlated with both subjective vestibular symptoms and objective measures of vestibular function on electronystagmography. In 2 patients, the resolution of symptoms 4 to 6 months later correlated with resolution of the enhancement on MRI. No labyrinthine enhancement was seen in a series of 30 control patients studied with the same MRI protocol. Labyrinthine enhancement in patients with auditory and vestibular symptoms is a new finding and is indicative of labyrinthine disease. While abnormalities on electronystagmograms and audiograms are nonspecific and only indicate a sensorineural problem, enhanced MRI may separate patients with retrocochlear lesions, such as acoustic neuromas, from those in whom the abnormal process is in the labyrinth or the brain.

MR imaging of acute transverse myelitis and AIDS myelopathy

Acute transverse myelitis (ATM) is a well recognized clinical entity, though its etiology remains obscure. Only a few reports of magnetic resonance imaging of ATM appear in the literature. These reports describe conflicting findings with respect to the signal intensity of the spinal cord on long repetition time (TR) sequences. The purpose of this study is to present our experience with five cases of ATM in which long TR sequences demonstrated abnormal increase in signal intensity of the cord. Magnetic resonance imaging also demonstrated extension of abnormal cord signal intensity over at least six spinal segments and above the clinically determined sensory level in four of five cases. Cord expansion was noted in two of five cases with normal myelograms. A case of acquired immunodeficiency syndrome (AIDS) myelopathy that demonstrated a similar high signal intensity of the cord is also presented. Our findings suggest that both ATM and AIDS myelopathy should be considered in the list of conditions that may result in a diffuse increase in the signal intensity of the cord on long TR sequences.

Ultrasound-guided fine-needle aspiration and thyroid disease.

ABSTRACT BACKGROUND: Fine-needle aspiration represents a critical diagnostic test in determining proper management of thyroid disease and the use of ultrasound-guided fine-needle aspiration (USGFNA) has increased over the years. METHODS: A retrospective chart review of patients undergoing USGFNA. Two hundred fifteen patients underwent 234 procedures with 362 nodules aspirated within a 2 ½-year period. RESULTS: The mean ages of women and men were 51.9 and 57.8, respectively. The average size of nodules was 2.1 cm. A difficult to assess gland or nodule was the most common indication for USGF-NA (33%). The sensitivity was 88.2%, specificity was 80.0%, the PPV was 65.2%, the negative predictive value was 94.1%, and the accuracy was 82.5%. The cancer yield, inadequacy, and complication rates were 44%, 10.5%, and 8.5%, respectively. CONCLUSIONS: USGFNA aspiration is a safe and effective diagnostic modality in the management of thyroid disease, especially for nodules that are difficult to palpate.

CT of aortoenteric fistulas

We compared CT findings with endoscopic, angiographic and surgical results in ten patients suspected of having an aortoenteric fistula (AEF) because of gastrointestinal bleeding (seven) or recurrent sepsis (three). CT correctly diagnosed AEF in six patients and excluded it in the other four. CT findings of AEF consisted of perigraft fluid (PGF) (5/6) and/or gas within the bed of the graft (4/6) later than three months after graft surgery. All six patients with AEF had perigraft infections; PGF with gas was found in 50%, PGF alone in 33%, and in one patient perigraft gas alone was found. Angiography and endoscopy failed to identify AEF. Our findings indicate that CT should be the initial imaging procedure in patients with suspected AEF who do not require immediate surgical intervention.

Changes in Size and Magnetic Resonance Signal Intensity of the Cerebral Csf Spaces During the Cardiac Cycle as Studied by Gated, High-resolution Magnetic Resonance Imaging

In 1966, du Boulay demonstrated the pulsatile nature of CSF flow in the cerebral aqueduct by using air cineventriculography, which disturbs normal CSF dynamics by replacing part of the incompressible CSF with air. To investigate this phenomenon noninvasively, 35 normal volunteers were studied using high-resolution, cardiac-gated MR imaging. Specifically, we wished to document changes in size and configuration of the CSF spaces and the incidence and magnitude of signal loss (an indication of CSF motion) in these spaces as they related to time in the cardiac cycle. Changes in size and configuration were measurable in the third ventricle only (size increased during systole in seven of the 35 volunteers). Except for the lateral ventricles, some loss in signal intensity was seen in all CSF spaces at least during systole in all 35 volunteers--findings consistent with those of du Boulay. However, contrary to du Boulays observations, asymmetric loss of signal, consistent with pulsatile CSF flow, was demonstrated at the level of the foramen of Monro in 15 of the 35 volunteers. Based on the pattern of flow void at the level of the foramen of Monro and on the expansion of the third ventricle during systole, we propose a theory of synchronous CSF flow at the foramen of Monro and aqueduct, which unifies our MR findings with du Boulays cineventriculographic observations.

VIRAL COCHLEITIS WITH GADOLINIUM ENHANCEMENT OF THE COCHLEA ON MAGNETIC RESONANCE IMAGING SCAN

Sudden hearing loss is a clinical diagnosis describing hearing losses of sensorineural origin. The time period before onset is usually 72 hours. Many also characterize the loss by a decrement of at least 30 dB in 3 contiguous test frequencies. 1 , 2 The causes are numerous, but one of the most frequent causes is a viral infection. 3 – 6 One strong indication of a viral cause is an acute antibody titer elevation with a subsequent 4-fold reduction in titer during the next 2 months. 3 – 6 Articles in the radiologic literature have chronicled the findings of enhancement of the inner ear with gadolinium MRI scans in cases of presumed viral infections. 7 , 8 This is the first article to report the MRI enhancement of the cochlea in 2 patients with seroconversion evidence of a viral cochleitis.

Gated acquisition of MR images of the thorax: Advantages for the study of the hila and mediastinum

Gated and nongated magnetic resonance (MR) scans of the chest were compared in five normal volunteers and 20 patients with chest disease to determine possible advantages of gated MR for delineation of noncardiac mediastinal anatomy. In order to compare gated and nongated images of the chest using similar imaging parameters, five spin-echo sequences were obtained in each of five normal volunteers: TR: 1000 msec, TE: 30 msec; gated to every heart beat (TR approximately 1000 msec, TE: 30 msec); TR: 2000 msec, TE: 30 msec; gated to every other heart beat (TR approximately 2000 msec), TE: 30 msec; TR: 500 msec, TE: 30 msec. In the 20 patients, the gated images were gated to every heart beat and the nongated images were obtained using a TR of 2000 msec, both with a TE of 30 msec. The noise in the periphery and in the center of the gated and nongated images at the level of the carina was compared in the five normal volunteers, using the signal intensity of the posterior chest wall as a control. There was 92% +/- 44% greater noise in the central region and 63% +/- 60% greater noise in the peripheral region on the nongated studies (TR: 1000 msec), than on the studies gated to every heart beat. In three of the five volunteers, the measured noise was greater on the nongated long TR (2000 msec) images than on the images gated to every other heart beat. However, the mediastinal structures below the level of the aortic arch were much better defined on the gated images in all five subjects.(ABSTRACT TRUNCATED AT 250 WORDS)

Sonographic evaluation of the rejecting ureter

In 10 mongrel dogs, the sonographic features of the pelvocaliceal system and ureteral peristalsis during acute rejection were correlated with the electromyographic (EMG) findings and histologic appearance. There were significant alterations of the ureteral dynamics during rejection as demonstrated by changes in the pressure tracings, the progressive decrease of electrical activity of the ureteral muscle, and decreased peristalsis with pelvicaliectasis as demonstrated on real-time ultrasound. The sonographic changes of peripelvic and periureteral thickening corresponded to histologic changes of edema and inflammatory infiltrate with disruption of the muscular layer. In the presence of clinical and sonographic findings of kidney rejection, the demonstration of hydronephrosis and thickened pelvic wall should be considered as another measure of the rejection process.