An incoherent HIFU transducer for treatment of the medial branch nerve: Numerical study and in vivo validation.

BACKGROUND: Chronic back pain due to facet related degenerative changes affects 4-6 million patients a year in the United States. Patients refractory to conservative therapy may warrant targeted injections of steroids into the joint or percutaneous medial branch nerve denervation with radiofrequency ablation. We numerically tested a novel noninvasive high intensity focused ultrasound transducer to optimize nerve ablation near a bone-soft tissue interface. METHODS: A transducer with 4 elements operating in an incoherent mode was modeled numerically and tested pre-clinically under fluoroscopic guidance. After 6 lumbar medial branch nerve ablations were performed in 2 pigs, they were followed clinically for 1 week and then sacrificed for pathological evaluation. RESULTS: Simulations show that the acoustic spot size in water at 6 dB was 14mm axial x 1.6mm lateral and 52mm axial x 1.6mm lateral for coherent and incoherent modes, respectively. We measured the size of N = 6 lesions induced in vivo in a pig model and compared them to the size of the simulated thermal dose. The best match between the simulated and measured lesion size was found with a maximum absorption coefficient in the cortical bone adjusted to 30 dB/cm/MHz. This absorption was used to simulate clinical scenarios in humans to generate lesions with no potential side effects at 1000 and 1500 J. CONCLUSION: The elongated spot obtained with the incoherent mode facilitates the targeting during fluoroscopic-guided medial branch nerve ablation.

Imaging of penetrating thoracic trauma.

The management of penetrating chest injuries has evolved significantly over the past few years, with an increasing emphasis on less invasive diagnostic and therapeutic modalities. Only 15% of patients need a therapeutic operative procedure. The challenge is to detect and treat these injuries rapidly while maximizing the use of noninvasive examinations and decreasing costs. The areas potentially at risk for injury include the heart, major vessels, thoracoabdomen, neck, spine, and aerodigestive tract. A review of injuries to these areas, including the use of new diagnostic modalities such as echocardiography and computed tomography (CT) scans, are discussed.

Noninvasive imaging of cervical vascular injuries.

Various imaging examinations can be used to diagnose cervical vascular injuries. The challenge in the current medical environment is to choose the imaging examination that is the most rapid, least invasive, and least costly. One must recognize the ability of each technique to detect lesions, taking into consideration the type of abnormality and whether the carotid or vertebral arteries are at risk for injury.

CT-revealed choroidal effusions as a sign of carotid cavernous fistula.

Choroidal effusions may appear as subtle abnormalities on CT scans. Recognition of choroidal effusions, however, is critical because they may be an early sign of ocular pathologic abnormality. After detection, the various causes of choroidal effusions, such as carotid cavernous fistulas, ocular hypotony, tumors, and inflammatory conditions, should be considered.

The acute diagnosis of Takayasu's arteritis based on helical CT angiography of the chest and neck in the emergency room.

Recently, a young woman presented acutely with a left hemispheric stroke and differing blood pressures in the arms as her initial manifestation of Takayasu's arteritis. Helical CT angiography, performed to rule out aortic dissection, revealed a thickened wall of the aortic arch with stenoses and occlusions of the great vessels, suggesting the diagnosis. The sequence of imaging studies and findings in this unusually catastrophic presentation of a typically insidious disease are highlighted.

Helical CT of cervical spine and soft tissue injuries of the neck.

Helical CT of the neck has revolutionized the diagnostic evaluation of trauma and emergency room patients. This comprehensive examination, with high resolution and fast acquisition times, allows the radiologist to make expeditious diagnoses concerning cervical spine fractures, vascular injuries, and aero-digestive tract lesions. This allows for the more rapid triaging and treatment of various injuries resulting in improved patient priate radiographic examination for each clinical scenario.

The use of duplex ultrasonography in penetrating neck trauma.

OBJECTIVE: To compare intraoperative findings and/or angiography with color-flow duplex scan. DESIGN: This prospective double-blind study was performed on all stable patients with zone 1, 2, or 3 penetrating neck trauma. Results of angiographic or intraoperative findings were compared with the results of duplex ultrasonographic scans. MAIN OUTCOME MEASURES: Fifty-five patients were studied over a 2-year period in which the distribution of injuries included 23 stab wounds (42%), 30 gunshot wounds (54%), and 2 motor vehicular lacerations (4%). There were 42 patients (76%) with normal ultrasonographic results and 13 patients (24%) with abnormal ultrasonographic results. The true-negative rate was 100%; however, there were 2 false positives resulting in 100% sensitivity and 85% specificity. CONCLUSIONS: Duplex ultrasonography provides an excellent diagnostic modality with cost-saving, patient-friendly characteristics and a low rate of morbidity. It should be instituted as the primary diagnostic procedure of choice for penetrating neck trauma.

Color Doppler sonography in penetrating injuries of the neck.

PURPOSE: To determine whether color Doppler sonography can be a sensitive alternative to screening arteriography for identifying arterial injury in patients with penetrating traumatic neck injuries. METHODS: Fifty-two patients admitted to our trauma center with penetrating neck injuries (gunshot wounds and lacerations) were examined prospectively with color Doppler sonography, and findings were compared with the results of angiography (n = 44), with findings at surgery (n = 4), and with clinical status (n = 4). RESULTS: Color Doppler sonography correctly detected all serious injuries of the carotid arteries (n = 6; 5 diagnosed at angiography and 1 at surgery) and all injuries of the vertebral arteries (n = 4; all diagnosed at angiography). Sonography missed 1 instance of reversible narrowing of the internal and external carotid arteries and did not show 2 normal vertebral arteries. CONCLUSION: Color Doppler sonography was as accurate as angiography in screening clinically stable patients with zone II or III injuries and no signs of active bleeding. Our initial results suggest that in the future, sonography may be used as a screening examination for arterial lesions in patients with penetrating neck injuries.

Enhancing meningeal blood vessels masquerading as leptomeningeal spread of tumor in obstructive hydrocephalus.

MR showed an enhancing mass in the pineal region and hydrocephalus and leptomeningeal enhancement, thought to indicate pinealoblastoma with leptomeningeal spread. During resection there was no evidence of spread, and repeat MR showed no residual tumor or meningeal enhancement, so the patient was not treated for metastasis. Because there were no signs of leptomeningeal tumor 4 months after surgery, the meningeal enhancement is thought to have been related to venous stasis secondary to obstructive hydrocephalus.

CNS Nocardia in AIDS patients: CT and MRI with pathologic correlation.

OBJECTIVE: Since CNS nocardiosis is an often fatal yet potentially treatable infection in HIV patients, we sought to identify and characterize imaging features that may suggest the diagnosis in the appropriate clinical setting. MATERIALS AND METHODS: The CT scan (six), MR scans (one), or both (two) were evaluated in nine HIV patients with pathologically proven CNS Nocardia asteroides. Chest X-ray films were available in seven patients. Findings were correlated with pathologic examination. RESULTS: All nine patients had brain abscesses, and in seven that received intravenous contrast agent, all lesions demonstrated ring enhancement. Five of nine patients had hydrocephalus and four of these had clinical evidence of meningitis. Small subependymal nodules were seen in five of nine patients and four of these also had meningitis. Pathologic examination in three of nine cases demonstrated a dense inflammatory infiltrate lining the ventricles that extended through the ependymal lining, producing small subependymal abscesses. Six of seven available chest X-ray films demonstrated infiltrates due to Nocardia. CONCLUSION: Our radiologic-pathologic correlation indicates that in an HIV-positive patient with enhancing parenchymal lesions, the additional findings of subependymal nodules and/or meningitis may suggest the diagnosis of nocardiosis. An associated pulmonary infiltrate can provide a clue to the diagnosis and serve as more accessible site for biopsy or culture.

Low-dose urokinase regimen for the treatment of lower extremity arterial and graft occlusions: experience in 132 cases.

In a retrospective review, a low-dose urokinase (UK) infusion regimen (mean, 87,000 U of UK per hour and 100 U of heparin per hour) was evaluated for lower extremity arterial and graft occlusions. Results of 132 infusions in 111 patients were analyzed to determine efficacy, limb salvage, and complications. Angiographic success was achieved with 126 infusions (95%), and amelioration of presenting signs and symptoms was achieved after 116 infusions (88%). Patients who underwent additional percutaneous procedures were more likely to have a successful outcome. There was no significant difference in success rates for patients receiving low-dose heparin through the arterial sheath (n = 101) versus those receiving concomitant systemic heparinization (n = 29), (P = .08) [corrected]. Of 88 threatened extremities (with rest pain, cold, ulcers, or gangrene), nine were amputated (limb salvage = 90%), accounting for 82% (nine of 11) of amputations in the overall study. Patients with zero- or one-vessel runoff before infusion were more likely to require limb amputation compared with the group with two- or three-vessel runoff before infusion (P less than .01). Major periprocedural complications occurred in nine of 132 (7%) infusions, five of which necessitated specific surgery and/or transfusion for bleeding. Pericatheter thrombosis was not encountered in either subgroup. This standard local low-dose infusion represents a safe and effective treatment for lower extremity arterial and graft occlusions.