Carbon dioxide and gadopentetate dimeglumine venography to guide percutaneous vertebroplasty.

Percutaneous vertebroplasty with polymethylmethacrylate (PMMA) is an effective procedure for relieving pain due to vertebral body compression fractures. The technique employs iodinated contrast venography to exclude needle placement directly within the basivertebral complex. We present two cases in which carbon dioxide (CO2) and gadopentetate dimeglumine venography was used to guide percutaneous vertebroplasty in patients with a contraindication to iodinated contrast.

Optic neuritis: imaging with magnetization transfer.

OBJECTIVE: Our objective was to prospectively examine the optic nerves in patients with clinically severe unilateral optic neuritis, using routine spin-echo and magnetization transfer MR imaging. SUBJECTS AND METHODS: For 39 patients with such lesions, we calculated the magnetization transfer ratio along the involved intraorbital optic nerve and along the asymptomatic contralateral optic nerve in a mirror-image location. Magnetization transfer ratios were correlated with the imaging findings on routine spin-echo MR imaging. RESULTS: Magnetization transfer ratios were decreased in 33 of the 39 clinically symptomatic optic nerves, including 12 of the 18 clinically symptomatic optic nerves in which no abnormality was seen on routine spin-echo MR images obtained before and after administration of gadopentetate dimeglumine. CONCLUSION: Magnetization transfer imaging reveals intraorbital optic nerve abnormalities in patients with optic neuritis even when such lesions are otherwise occult on routine magnetization transfer imaging.

Cervical prevertebral soft-tissue measurements and chest radiographic findings in acute traumatic aortic injury.

Acute traumatic aortic injury (ATAI) results in several characteristic chest radiographic findings, most notably mediastinal widening. This study was based on the hypothesis that blood or fluid in the widened mediastinum might track up into the neck and be detected on lateral cervical radiographs. In a blinded, retrospective, case-control review of radiology files, 13 consecutive adult cases of ATAI were identified and compared with 19 cases of negative aortography (NAO) and 18 multiple trauma victims (MT) without aortography. Cases with inadequate cervical films or cervical injury were excluded. Measurements included the cervical soft-tissue (ST) width at the third (C3) and sixth (C6) cervical vertebrae, mediastinal width, mediastinal-chest width ratio, and the presence of several characteristic chest radiograph findings of ATAI. The C3 ST measurements averaged 9.1 +/- 2.8 mm, 8.5 +/- 2.7 mm, and 6.9 +/- 2.2 mm for the ATAI, NAO, and MT groups, respectively. The C6 ST measurements averaged 19.2 +/- 4.5 mm, 18.6 +/- 3.9, and 16.5 +/- 3.8 mm for the ATAI, NAO, and MT groups, respectively. These cervical ST values were not significantly different between groups at either C3 (P = .188) or C6 (P = .148). The incidence of abnormal ST swelling of >7 mm at C3 was 38%, 53%, and 33% for the ATAI, NAO, and MT groups, respectively. The incidence of abnormal ST swelling of >20 mm at C6 was 54%, 42%, and 11% for the ATAI, NAO, and MT groups, respectively. Cervical ST measurements at C3 or at C6 did not correlate with mediastinal-chest width ratios. Mediastinal widening, aortopulmonic window opacification, and blurring of the aortic knob were the most sensitive chest radiography findings in ATAI, although each of these lacked useful specificity and accuracy. Cervical ST swelling is not a useful marker for ATAI.

Magnetization transfer imaging of periventricular hyperintense white matter in the elderly.

PURPOSE: To characterize with magnetization transfer imaging the pathologic substrate of the nonspecific periventricular hyperintense white matter changes seen on T2-weighted images of elderly patients. METHODS: Twenty-one elderly patients with periventricular hyperintense white matter on T2-weighted MR images and eleven control subjects were studied using MT technique. Magnetization transfer ratios (MTRs) were calculated for the periventricular hyperintense white matter and normal-appearing white matter. These MTRs were correlated with histopathologic changes that have previously been reported as well as with established MTRs for other lesions. RESULTS: The MTRs (mean, 35.2; SD, 1.2) in the periventricular hyperintense white matter are lower than those in the normal white matter of the patient (mean, 40.8; SD, 1.4) and control (mean, 41.3; SD, 1.8) groups. These MTRs are much higher than those of demyelinating lesions but are similar to those of experimental lesions with just edema. CONCLUSION: Because MTR may reflect to some extent histopathologic changes and thus provide more specificity than conventional pulse sequences, the main pathologic substrate accounting for the lower MTR in periventricular hyperintense white matter is probably the increased water content in reactive astrocytes.

CT diagnosis of unsuspected traumatic cataracts in patients with complicated eye injuries: significance of attenuation value of the lens.

OBJECTIVE: The purpose of this study was to determine whether the CT attenuation value of the lens is helpful in diagnosing acute traumatic cataracts in patients with complicated eye injuries that preclude evaluation by any other means. SUBJECTS AND METHODS: The CT attenuation values of the lenses of 69 patients with acute orbital trauma, including 24 patients with clinically and surgically diagnosed acute traumatic cataracts, were compared with attenuation values of their own contralateral lens and with the attenuation values of the lenses of 103 consecutive asymptomatic control subjects. The study group was composed of consecutive patients with unilateral orbital trauma who were clinically evaluated and referred for CT examination within 48 hr after their initial injury. In all patients, attenuation measurements of the injured lenses were obtained and compared with those of the contralateral lens as an internal control. All surgically diagnosed cataracts were histologically confirmed. RESULTS: The CT attenuation measurement of a lens in any asymptomatic control subject was identical (within the range of the standard deviation) to the measurement of the contralateral lens of that control patient. In patients with orbital injury, the CT attenuation of the patient's cataractous lens was markedly lower than in the contralateral lens (mean density difference, 30 H, p < .0001). This decreased attenuation corresponds to acute cataract formation with increased fluid within the lens. No patient with normal attenuation values of the lens in the traumatized globe (as compared with the contralateral lens) was found to have an acute traumatic cataract or have a cataract develop within a 1-year follow-up period. CONCLUSION: CT may be useful in the examination of patients with acute traumatic cataracts, unsuspected lens injury, opacification of the anterior chamber, or other injuries of the globe with complications that preclude lens evaluation by any other means. This prompt diagnosis may allow timely removal of the lens in appropriate clinical circumstances, preventing damage to the anterior chamber of the globe and other complications of delayed diagnosis and treatment. Further, normal CT findings at the time of trauma suggest that the lens will not undergo acute traumatic cataract formation.

Metastatic lesions of the brain: imaging with magnetization transfer.

PURPOSE: To study solitary metastatic lesions of the brain with routine spin-echo (SE) and magnetization transfer (MT) magnetic resonance (MR) imaging. MATERIALS AND METHODS: In 15 patients with such lesions, the MT ratio (MTR) was calculated in the center and at the periphery of the metastatic lesion, and distally in adjacent white matter, from the periphery of the lesion radially to the most distant cortex. It also was calculated for mirror-image locations in the opposite hemisphere to provide control values. RESULTS: MTRs were decreased in and immediately around the site of the metastatic focus. MTRs also were lower than control values far distal to the metastatic focus, even when no abnormality was seen on SE MR images obtained before and those obtained after administration of gadopentetate dimeglumine. CONCLUSION: MT enables demonstration of white matter abnormalities in patients with metastatic lesions not seen on SE MR images. These changes can be found in white matter far distal to the lesion and surrounding areas of edema.

Magnetic resonance imaging of the shoulder.

The authors have reviewed the field of magnetic resonance imaging of the shoulder. This review includes abnormalities of the rotator cuff mechanism and glenoid labrum, and other disorders.

Computed tomography of musculoskeletal trauma.

Radiology plays a crucial role in the evaluation of the acutely traumatized patient by providing information that allows timely and appropriate management to be instituted. With few exceptions, notably the skull, plain films remain the primary imaging technique for the diagnosis of skeletal trauma. Computed tomography (CT) has become an important adjunctive procedure in the evaluation and diagnosis of trauma, particularly in complex anatomic areas, including the sternoclavicular joint, the pelvis, and the spine, and in many hospitals has virtually replaced conventional tomography. It may be combined with arthrography or enhanced by intravenous or intrathecal contrast material. This article reviews the uses of CT in the diagnosis and evaluation of musculoskeletal trauma and its complications.

Using helium-oxygen mixtures in the emergency management of acute upper airway obstruction.

Helium (80%)-oxygen (20%) mixtures (He-O2) are less dense and less viscous than room air. Respiratory work to overcome upper airway obstruction from a number of pathologic conditions may be reduced by inhaling He-O2 instead of room air. We present the case of a 23-year-old woman with a history of asthma and tracheal angioedema refractory to conventional antiasthma and even immunosuppressive therapy. She had previously required frequent intubation and mechanical ventilatory support. During the most recent episode of respiratory distress, prior to intubation as access for mechanical ventilatory support, the patient was placed on He-O2 by a nonrebreathing face mask. She improved clinically within minutes, and continuous pulse oximetry showed a rise in oxygen saturation from 91% to 98%. The patient's condition stabilized and intubation was not required during the subsequent hospitalization. He-O2 may be beneficial in certain patients with acute upper airway obstruction as a noninvasive, temporizing therapy with minimal adverse effects. We recommend close monitoring of the clinical response and the use of continuous pulse oximetry, substantiated by arterial blood gases when feasible.

Pharmacologic treatment of occlusive mesenteric ischemia in rats.

This study assessed the contribution of angiotensin II, oxygen-free radicals, and vasopressin to the mortality of acute mesenteric ischemia in rats. Rats received saline replacement (16 ml/kg/hr) for 3 hr during and after 85 min of superior mesenteric artery (SMA) occlusion. Only 21% of rats that received saline alone (n = 14, control) survived 48 hr, significantly less than the 100% survival of sham-operated rats (no SMA occlusion, n = 5, P less than 0.01). Neither teprotide (an angiotensin converting-enzyme inhibitor), allopurinol (to reduce oxygen-free radical formation), nor a specific vasopressin antagonist [1-(beta-mercapto-beta,beta-cyclopentamethyleneproprionic acid), 2-(O-methyl) tyrosine arginine-vasopressin] improved 48-hr survival, which was 17% in each group (n = 6, each). Survival improved significantly to 86% (n = 7, P less than 0.001) when intravenous glucagon (1.6 micrograms/kg/min) was given for 2 hr after SMA reperfusion. Survival after dopamine infusion (12 micrograms/kg/min iv) was 67% at 48 hr, a nearly significant improvement (n = 9, P less than 0.06). These results suggest that angiotensin II, oxygen-free radicals, and vasopressin do not contribute significantly to the high mortality observed after acute intestinal ischemia in this rat model, but that glucagon, and to a lesser extent, dopamine, are potentially therapeutic.

Effect of thromboxane synthetase inhibition on canine autogenous vein grafts.

This study examined the effect of an orally active thromboxane (TXA2) synthetase inhibitor (TSI) on the patency, TXA2 production, and platelet accumulation of reversed autogenous vein grafts. Ten dogs received TSI (U-63557A) 10 mg/kg po q8 hr for 6 weeks, beginning 24 hr prior to surgery, while 15 control dogs were untreated. One jugular vein was harvested and stored in 37 degrees C saline for 1 hr to induce mild endothelial injury (stored). Normal and stored jugular vein grafts (8 cm) were then implanted in opposite femoral arteries while 3-cm segments of the same veins were implanted in the carotid arteries. Femoral graft flow was restricted with a 5 Fr distal arterial stenosis and patency determined by arteriography at 1, 2, 4, and 6 weeks. Vein graft endothelial surface TXB2 production was measured by RIA at graft implantation and in carotid grafts harvested at 1 week. 111In-labeled platelets were given iv 24 hr prior to carotid graft harvest to determine graft-platelet deposition. TSI treatment improved early (1 week) femoral vein graft patency from 63 to 89% (P less than 0.05), a trend that persisted for 6 weeks. Warm saline storage reduced 1-week graft patency from 83 to 63% (P less than 0.05), a difference that decreased with time. TSI treatment resulted in a marked decrease in TXB2 production, but was not associated with decreased 111In-labeled platelet deposition in carotid vein grafts. Warm saline storage increased graft-platelet deposition which was predominant at the arterial anastomoses. TSI treatment may improve early vein graft patency during the transient period of endothelial injury.