A field study of a roof bolter canopy air curtain (2nd generation) for respirable coal mine dust control.

A 2nd generation roof bolter canopy air curtain (CAC) design was tested by National Institute for Occupational Safety and Health (NIOSH) at a Midwestern underground coal mine. During the study, the roof bolter never operated downwind of the continuous miner. Using a combination of personal Data Rams (pDR) and gravimetric samplers, the dust control efficiency of the roof bolter CAC was ascertained. Performance evaluation was determined using three methods: (1) comparing roof bolter operator concentrations underneath the CAC to roof bolter concentrations outside the CAC, (2) comparing roof bolter operator concentrations underneath the CAC to the concentrations at the rear of the bolter, and finally, (3) using the gravimetric data directly underneath the CAC to correct roof bolter operator concentrations underneath the CAC and comparing them to the concentrations at the rear of the bolter. Method 1 dust control efficiencies ranged from -53.9% to 60.4%. Method 2 efficiencies ranged from -150.5% to 52.2%, and Method 3 efficiencies ranged from 40.7% to 91%. Reasons for negative and low dust control efficiencies are provided in this paper and include: incorrect sampling locations, large distance between CAC and operator, and contamination of intake air from line curtain. Low dust concentrations encountered during the testing made it difficult to discern whether differences in concentrations were due to the CAC or due to variances inherent in experimental dust measurement. However, the analyses, especially the Method 3 analysis, show that the CAC can be an effective dust control device.

Testing the stand-alone microbeam at Columbia University.

The stand-alone microbeam at Columbia University presents a novel approach to biological microbeam irradiation studies. Foregoing a conventional accelerator as a source of energetic ions, a small, high-specific-activity, alpha emitter is used. Alpha particles emitted from this source are focused using a compound magnetic lens consisting of 24 permanent magnets arranged in two quadrupole triplets. Using a 'home made' 6.5 mCi polonium source, a 1 alpha particle s(-1), 10 microm diameter microbeam can, in principle, be realised. As the alpha source energy is constant, once the microbeam has been set up, no further adjustments are necessary apart from a periodic replacement of the source. The use of permanent magnets eliminates the need for bulky power supplies and cooling systems required by other types of ion lenses and greatly simplifies operation. It also makes the microbeam simple and cheap enough to be realised in any large lab. The Microbeam design as well as first tests of its performance, using an accelerator-based beam are presented here.

MR imaging of primary pancreatic leiomyosarcoma.

Primary leiomyosarcoma of the pancreas is a rare neoplasm with only 17 reported cases in the literature. Although the ultrasonic and computed tomographic appearances have been described, the magnetic resonance features of pancreatic leiomyosarcomas have not. In this report, we describe the MR characteristics of a primary pancreatic leiomyosarcoma which was an incidental finding on ultrasound. The unenhanced T1 weighted and T2 weighted images were the most useful in tumour localization whereas the enhanced images actually obscured the tumour within the pancreas. Differentiation from the much more commonly occurring adenocarcinoma was impossible.

Colloid cyst of the third ventricle: radiologic-pathologic correlation.

We describe a patient with a large colloid cyst of the third ventricle and resultant hydrocephalus. An unenhanced brain CT demonstrated the central portion of the mass to be of increased density relative to the peripheral portion. On T1-weighted images, the central portion of the mass was of increased signal intensity relative to brain, whereas the periphery was isointense. On T2-weighted images, the central portion was markedly hypointense to brain, while the peripheral portion was isointense. These imaging findings corresponded to an actual pathological difference between the central and peripheral portions of the mass. The central portion was solid, whereas the periphery was liquid. Since no histological difference was identified between the central and peripheral portions of the mass, we hypothesize that the differences in densities on CT and signal characteristics on MR were related to the state of hydration in the mass where the central portion possibly had a higher protein concentration than the periphery.

Transient osteoporosis of the knee.

The MR findings in transient osteoporosis of the knee have been described as showing a diffuse area of decreased signal intensity (relative to normal bone marrow) on T1-weighted images and increased signal intensity on T2-weighted images. We report a case of transient osteoporosis, in which MRI showed a crescentic area of abnormal signal intensity in the posterior portion of the lateral femoral condyle, which was bordered by a rim of low signal intensity, best seen on the T2-weighted images. This abnormality was shown to resolve on follow-up MR scans.

Spontaneous healing of basilar artery dissection: MR findings.

We report a case of a dissecting basilar artery aneurysm, which presented with subarachnoid hemorrhage in a 34-year-old woman. Although the natural history has been described as severe with mortality approaching 80%, this patient did well and spontaneous healing was demonstrated on MR and angiography.

MR imaging of the most commonly injured ankle ligaments. Part I. Normal anatomy.

To determine the optimum foot position and imaging plane at magnetic resonance (MR) imaging of each ankle ligament, 10 cadaver ankles were dissected to visualize the orientation, precise attachment sites, and relationships of each ligament. Then eight cadaver ankles were studied with MR imaging and were cryosectioned in the optimum imaging planes. The ankles of 12 healthy volunteers were imaged to ensure consistency in identifying the normal ligaments. With the foot taped into full dorsiflexion of 10 degrees-20 degrees, axial imaging provided optimum views of the anterior, posterior, and inferior tibiofibular ligaments and of the anterior and posterior fibulotalar ligaments and provided an overview of the deltoid ligament. Coronal images provided full-length views of the tibiospring, tibiocalcaneal, and posterior tibiotalar parts of the deltoid ligament. With the foot taped into full plantar flexion of 40 degrees-50 degrees, axial imaging optimized visualization of the fibulocalcaneal ligament and of the tibionavicular and anterior tibiotalar parts of the deltoid ligament. Sagittal images provided the best full-length views of the spring ligament.

Retroaortic renal vein with tumor thrombus: MR findings.

The magnetic resonance (MR) findings in a case of tumor extension into a retroaortic renal vein from a renal cell carcinoma are reported. The signal characteristics of the tumor thrombus paralleled those of the renal mass, and the preoperative recognition of the anomalous vessel lead to an altered surgical approach.

Case report 723. Popliteal artery aneurysm.

An unusually large, noncalcified popliteal artery aneurysm causing cortical erosion was erroneously diagnosed as a soft-tissue sarcoma. The case stresses the importance of excluding a vascular cause of a mass whenever biopsy is considered. We review the clinical and radiological features of popliteal artery aneurysm and describe the appearance of the aneurysm on MR.

Hemodialysis-related amyloidomas of bone.

Lytic bone lesions secondary to amyloid deposition are a recently described complication of long-term hemodialysis. The authors refer to these tumorlike deposits as amyloidomas in a review of the subject and four proved cases. This entity typically appears as multiple well-defined, juxta-articular lytic lesions without matrix calcification. The duration of hemodialysis is probably the greatest risk factor for development of these intraosseous amyloidomas. Ultrastructurally, this new type of amyloid originates from beta 2-microglobulin, a low-molecular-weight serum protein that is not filtered by standard dialysis membranes.

Sonographically guided paracentesis for palliation of symptomatic malignant ascites.

The technique, results, and complications of 109 consecutive sonographically guided therapeutic paracenteses performed on 43 patients with malignant ascites are summarized. A 5.5-French Sacks One-Step Catheter was used in all cases but five in which tissue resistance prohibited passage of the catheter through the abdominal wall. The procedure was performed on an inpatient basis 70 times and in an outpatient setting 39 times. Colonic, ovarian, and breast carcinomas accounted for over 50% of the tumors resulting in malignant fluid collections. Three complications (hypotension, 2.6%) were directly related to the procedure; two of them were fatal (1.6%). The amount of ascitic fluid drained within the first 24 hr averaged 3.5 l at rates of 100-150 ml/sec. Ninety-five procedures (87%, in 39 patients) resulted in improvement of symptoms after drainage as manifested by decreased pain from abdominal distention, alleviation of nausea, improved appetite, or decreased dyspnea. The duration of symptomatic relief ranged from 4 days to 45 days (mean, 10.4 days). Sonographically guided paracentesis is an effective procedure that can be performed for short-term relief of symptoms caused by malignant ascites.

Isolated avulsion fracture of the lesser tuberosity of the humerus: report of two cases.

Isolated avulsion fractures of the lesser tuberosity of the humerus are exceptionally rare. Two cases are reported here, each involving a 12-year-old boy. The mechanism of injury appears to be a strong external rotatory force applied while the arm is at maximum external rotation and approximately 60 degrees of abduction. In children and adolescents the fracture most likely occurs through the apophyseal plate of the lesser tuberosity (traction epiphysis). In adults, clinical differentiation from the far more common calcific peritendinitis of the rotator cuff can be difficult. Whereas large, displaced fractures can be easily demonstrated on anteroposterior radiographs with internal and external rotation of the humerus, the axillary view is often necessary to detect smaller fragments with little displacement.

Intravascular bronchioloalveolar tumor: CT and pathologic correlation.

Intravascular bronchioloalveolar tumor of the lung is an unusual neoplasm that usually presents as multiple pulmonary nodules in asymptomatic young women. The course of the disease is often indolent with some patients eventually dying of respiratory failure secondary to progressive tumor infiltration of the pulmonary interstitium. The cell of origin appears to be an endothelial cell, and epithelioid hemangioendothelioma of liver or other soft tissues is a pathologically identical neoplasm. Open lung biopsy is necessary for diagnosis. The radiologist should be aware of this tumor and suggest the diagnosis in the appropriate clinical setting.

Popliteal venous aneurysm.

Two new cases of popliteal venous aneurysm, confirmed with findings from venography, are added to seven previously reported cases revealed in the authors' search of the English-language literature. This rare anomaly usually shows as recurrent pulmonary emboli in patients with no underlying predisposition to deep venous thrombosis. Physical examination is usually not helpful in the diagnosis. Results of combined real-time and Doppler ultrasound should indicate the diagnosis, but venography is necessary for confirmation and further anatomic detail. Surgical treatment has been fraught with complications. Eight patients, including these two new cases, have undergone surgery, and none have had a recurrence of pulmonary embolism following surgery.