New symptomatic compression fracture after percutaneous vertebroplasty at the thoracolumbar junction.

BACKGROUND AND PURPOSE: The purpose of this study was to investigate the risk factors for new symptomatic vertebral compression fractures after vertebroplasty at the thoracolumbar junction. MATERIALS AND METHODS: We conducted a retrospective analysis of 53 patients treated with percutaneous vertebroplasty at the thoracolumbar junction (T12, L1). The follow-up period was 15-27 months. The occurrence of new symptomatic vertebral compression fractures was recorded after vertebroplasty. We evaluated patient age and sex, amount of injected cement, vacuum clefts in the collapsed bodies, initial wedge angle of the compression fracture, change of the wedge angle after vertebroplasty, intradiskal cement leak, and percentage of height restoration of the vertebral body. In this report, we surveyed the possible risk factors for new symptomatic vertebral compression fractures. RESULTS: Thirty-nine (74%) of the 53 patients had fluid and/or air in the compression fracture at the thoracolumbar junction (T12, L1). Eight (20.5%) of the 39 patients with vacuum clefts had new symptomatic compression fracture after vertebroplasty between 1 month and 4 days after surgery to 23 months and 4 days after surgery. The patients with new symptomatic compression fracture had higher initial wedge angle and wedge angle change (more than 7 degrees ) after vertebroplasty than those without fractures; these data were considered statistically significant. CONCLUSIONS: The incidence of vacuum clefts in the compression fracture at the thoracolumbar junction is high (74%). The severity of initial wedge angle and wedge angle change affects the incidence of new symptomatic compression fracture.

Dynamic CT perfusion imaging with acetazolamide challenge for evaluation of patients with unilateral cerebrovascular steno-occlusive disease.

BACKGROUND AND PURPOSE: Perfusion CT (PCT) has the ability to measure quantitative values and produce maps of cerebral blood flow (CBF), cerebral blood volume (CBV), and mean transit time (MTT). We assessed cerebral hemodynamics by using these parameters and acetazolamide challenge in patients with cerebrovascular steno-occlusive disease. METHODS: Fifteen patients underwent PCT with acetazolamide challenge. Comparison of mean CBF, CBV, and MTT was determined between hemispheres and before and after acetazolamide challenge. Hemispheric ratio and percent change due to acetazolamide administration were also calculated. Absolute values and percent changes 2 SDs outside the mean from the nonstenotic hemispheres were defined as abnormal. RESULTS: Significant decreases in CBF (-25.1%, P = .003) and significant increases in MTT (47.1%, P < .001) were found in stenotic hemispheres. After acetazolamide challenge, significant changes in CBF (-39.5%, P < .001) and MTT (92.9%, P < .001) were also seen. The acetazolamide test significantly decreased CBF hemispheric ratio (-20.3%, P < .001) and increased MTT hemispheric ratio (30.8%, P = .002), making both maps more asymmetric. Significance in CBF and MTT percent changes (P < .001 and P = .005, respectively) was found between hemispheres. When CBF percent changes were assumed to represent the true determinant of hemodynamic impairment, normal ranges of baseline MTT value and MTT percent changes demonstrated sensitivities of 66.7% and 100% and specificities of 58.3% and 75%, respectively, for detecting patients with hemodynamic impairment. CONCLUSION: Parameters obtained from PCT with acetazolamide are promising for the evaluation of cerebral hemodynamics in patients with cerebrovascular steno-occlusive disease.

CNS Clostridium perfringens infection: a rare complication of preoperative embolization of meningioma.

Gas gangrene is a severe form of gangrene (tissue death) that usually is caused by Clostridium perfringens. It generally occurs at the site of trauma or a recent surgical wound. We report the case of a 45-year-old woman with sphenoid-ridged meningioma who received preoperative transarterial embolization with polyvinyl alcohol. The patient later developed an intratumoral C perfringens infection and died despite intensive medical care. The case represents an extremely rare complication following transarterial embolization of meningioma.

MR findings of penile lymphoma.

Penile lymphoma is extremely rare and secondary involvement of the penis by lymphoma may be due to retrograde spread or to direct extension from neighbouring organ. The appearance of penile lymphoma varies and can be mistaken for other soft tissue tumours. We report on a case with malignant lymphoma of the penis. MRI findings revealed soft-tissue mass of homogeneous isointensity around the middle to distal part of penis on T(1) weighted imaging and T(2) weighted imaging. It was well encapsulated, minimally enhanced and distinct from corpus cavernosum and corpus spongiosum.

CT angiography of intracranial aneurysms: advantages and pitfalls.

OBJECTIVE: To determine the clinical usefulness of computed tomography (CT) angiography in the evaluation of cerebral aneurysms. MATERIALS AND METHODS: From October 1994 through April 1996, 26 patients with 30 surgical proven intracranial aneurysms underwent both CT angiography and catheter cerebral angiography. The findings of the two methods were reviewed independently and then compared with each other. RESULTS: Comparing with catheter angiography, CT angiography was superior in demonstrating the aneurysmal neck in seven aneurysms but was inferior in one. The thrombosed part and calcification of aneurysms were clearly demonstrated on CT angiograms. CT angiography also aided in differentiating tight vascular loops from aneurysms. On CT angiograms, one posterior communicating arterial aneurysm was overlooked and another anterior choroidal artery aneurysm was misinterpreted as a posterior communicating artery aneurysm. Of note were two patients in whom the infundibulum of the orbitofrontal artery was misinterpreted as the anterior communicating artery aneurysm. CONCLUSION: CT angiography can compliment conventional catheter angiography for its better demonstration of the 3-dimensional anatomy. It can provide surgical information about the neck, calcification and thrombosed part of an aneurysm and its relation to adjacent structures. However, caution is advocated because CT angiography may fail to demonstrate small but important vessels such as posterior communicating, anterior choroidal and orbitofrontal arteries. Recognition of the limitations of CT angiography is important in minimizing interpretation errors.

Errors in bound water measurements using centrifugal settling method.

Centrifugal settling method (CSM) is commonly used to estimate the bound water content in sludges. The sludge sediment matrix should be purely plastic for accurate measurements to the bound water content. This communication, however, addressed for the first time that, owing to the inhibited elasticity of the sludge matrix, sediment height rebound was commonly observed for the flocculated sludge. Also, different sludges could have distinct elastic responses after centrifugation. There existed no simple correlation to incorporate the elastic rebound of sludge sediment in bound water measurement. The possible errors incorporated into CSM for measuring bound water contents were highlighted.

High-speed sludge freezing.

The investigation examined the feasibility of applying a "high-speed freezing technique, using liquid nitrogen freezing, to condition activated sludges and alum sludges. Experimental results indicate that the freezing speed is much faster than that adopted in most previous works on sludge freezing. Although the filterability and settleability of the alum sludge is improved by 3-min liquid nitrogen freezing, no similar improvement is observed for activated sludge. Moreover, curing affects neither sludge after liquid nitrogen freezing, but affects the slow-freezing activated sludge.

Advective flow and floc permeability.

This work monitored advection flow through a floc by bubble tracking. Close examination of the motion of a swarm of hydrogen bubbles that passed over a free-falling floc allowed the extent of advection flow to be estimated at 53% for the original activated sludge floc, and 12% for the flocculated floc. The interior permeability of the sludge flocs was estimated from this information. The fluid force exerted on the falling floc was also considered.

Preoperative embolization of meningiomas: comparison of superselective and subselective techniques.

We retrospectively compared the efficacy of preoperative superselective and subselective embolization for intracranial meningiomas. Between January and December 1996, 22 patients (7 men, 15 women, mean age 51 +/- 15.5 yr) underwent superselective embolization with 45 to 150 mm polyvinyl alcohol particles after superselective catheterization of the feeding vessels with a microcatheter system. Another 30 patients (12 men, 18 women, mean age 50 +/- 12.9 yr) underwent subselective embolization between January and December 1995 with 150 to 300 mm Gelfoam particles after catheterization of the terminal external carotid artery just proximal to the orifice of the maxillary artery with a 4- or 5-F angiocatheter. The mean intraoperative blood loss (918 versus 1450 mL, p < 0.05), amount of blood transfused (4.9 versus 7.5 units, p = 0.09), and surgical resection time (422 versus 529 min, p < 0.05) were all lower in the superselective group than in the subselective group, while the occurrence of fresh ischemic necrosis (59% versus 53%, p = 0.68), hemorrhage (77% versus 60%, p = 0.19), and embolic material (55% versus 13%, p < 0.05) on pathologic examination were higher in the superselective group. No procedure-related complications occurred in the superselective group, whereas two patients in the subselective group had postoperative scalp necrosis. Our findings show that superselective embolization is more effective than subselective embolization for preoperative endovascular devascularization of meningiomas, with significant reductions in intraoperative blood loss and surgery time. Preoperative embolization of meningiomas, if indicated, should be done with the superselective technique whenever feasible.

MR spectroscopy and MR perfusion character of cerebral sparganosis: a case report.

The authors report the case of a 46-year-old woman with cerebral sparganosis resulting from infection with a larva of Spirometra. Computed tomography and magnetic resonance imaging revealed a mass lesion with prominent perifocal oedema in the left parietal lobe. Advanced imaging pulse sequences, including MR spectroscopy and MR perfusion, were performed. During surgery for the removal of a granuloma, the parasite was discovered and excised. Following treatment, the patient's neurological deficits markedly improved.

Coronary artery air embolism: a potentially fatal complication of CT-guided percutaneous lung biopsy.

CT-guided transthoracic lung biopsy is becoming a widely accepted procedure for the diagnosis of pulmonary lesions. The rate of severe complications following such a procedure has been reported. Of these complications, air embolism is the most likely to be fatal. We report a case of right coronary air embolism resulting in myocardial infarction after a CT-guided percutaneous needle biopsy of the lung. The patient died from underlying malignant disease 4 months later.

Reinforcement of acrylic denture base resin by incorporation of various fibers.

This study was designed to evaluate improvements in the mechanical properties of acrylic resin following reinforcement with three types of fiber. Polyester fiber (PE), Kevlar fiber (KF), and glass fiber (GF) were cut into 2, 4, and 6 mm lengths and incorporated at concentrations of 1, 2, and 3% (w/w). The mixtures of resin and fiber were cured at 70 degrees C in a water bath for 13 h, then at 90 degrees C for 1 h, in 70 x 25 x 15 mm stone molds, which were enclosed by dental flasks. The cured resin blocks were cut to an appropriate size and tested for impact strength and bending strength following the methods of ASTM Specification No. 256 and ISO Specification No. 1567, respectively. Specimens used in the impact strength test were reused for the Knoop hardness test. The results showed that the impact strength tended to be enhanced with fiber length and concentration, particularly PE at 3% and 6 mm length, which was significantly stronger than other formulations. Bending strength did not change significantly with the various formulations when compared to a control without fiber. The assessment of Knoop hardness revealed a complex pattern for the various formulations. The Knoop hardness of 3%, 6 mm PE-reinforced resin was comparable to that of the other formulations except for the control without fiber, but for clinical usage this did not adversely affect the merit of acrylic denture base resin. It is concluded that, for improved strength the optimum formulation to reinforce acrylic resin is by incorporation of 3%, 6 mm length PE fibers.

Nasopharyngeal carcinoma: MRI and CT assessment.

Precise assessment of the extent of nasopharyngeal carcinoma (NPC) represents the basic step towards optimal treatment. We compared the capacity of CT and MRI in assessing the extent of NPC in 67 patients. MRI was superior to CT in demonstrating lesions in the retropharyngeal node, skull base, intracranial area, carotid space, longus colli muscle and levator palatini muscle. Of 25 cases in which retropharyngeal adenopathy was recognised only on MRI, seven had been reported as showing oropharyngeal involvement and 18 as primary extension to the carotid space on CT. MRI showed skull-base involvement in 40 patients compared with 27 on CT and intracranial involvement in 38 patients versus 24 on CT. There was not a single case in which skull base invasion was seen on CT but not on MRI. MRI enabled improved recognition of tumour infiltration of longus colli muscles (34 cases compared with 15 on CT). It allowed us to clarify 12 questionable sinonasal opacities on CT. Overall, T-staging was changed in 18 of 67 patients (26.9%), including upstaging in 15 cases and down-staging in 3 cases, after comparing CT with MRI. The nodel status was changed from negative on CT to positive on MRI in 4 of 67 patients (6%). We believe that MRI allows more accurate evaluation of the extent of NPC than CT and should be the primary mode of investigation.