Management of intracranial meningeal hemangiopericytomas: outcome and experience

Hemangiopericytomas represent rare intracranial tumors that have a tendency to recur locally and have the unique characteristic of giving extracranial metastases. Our current communication reviews a series of patients diagnosed with hemangiopericytoma who were treated in our facility. Eleven patients with a mean age of 51.2 years underwent follow-up for a mean time of 7.1 years. Their neuroimaging preoperative evaluation included plain skull X-rays, head CT scans, brain MRI, angiograms, and (1)HMRS. Preoperative embolization of the tumor was employed in 6/11 patients. All patients underwent craniotomy for tumor resection and postoperative radiation treatment was employed on all but one. Grade I resection was accomplished in 6/11 (54.5%), grade III in 4/11 (36.4%), and grade IV in 1/11 (9.1%). Local recurrence was detected in 3/11 (27.3%) at a mean period of 5 (range 2-7.5) years. Extracranial metastatic disease was documented in 4/11 (36.4%) patients at a mean of 4.9 (range 2.5-7) years after the initial diagnosis. The GOS score was: 7/11 (63.6%) scored 5, while 4/11 (36.4%) died at a mean time of 5.5 (range 3-8) years after the initial diagnosis. Intracranial hemangiopericytomas management requires aggressive surgical resection, postoperative radiation treatment, and extensive follow-up to rule out local recurrences and delayed extracranial metastases.

The development and evaluation of the UK national telepathology network

AIMS

As technology advances and costs fall, it may be anticipated that soon every histopathologist will expect to be able to exchange electronic images with colleagues. Arguing that the value of a network increases as more people are connected, we sought to install a simple, low-cost telepathology system into any histopathology laboratory which requested it within the UK.

METHODS AND RESULTS

We assumed that laboratories had microscopes, computers and internet access. We offered low-cost video cameras, video input cards, software and training to any histopathology department requesting installation, limited only by resources supplied by the UK government. We also established central servers and a website with 'help' files. After 1 year we studied system use and pathologists' opinions by circulating a questionnaire. Installations were completed in 35 laboratories; there are currently 66 registered users of the system, with 16 identified 'experts' covering most organ systems. Serious difficulties were caused by institutional firewalls and reluctance of local information technology (IT) staff to make changes to facilitate the installation or to help resolve subsequent network problems. After installation, many of the telepathology systems remain unused. Concerns were expressed about image quality, though mainly by pathologists who had not used the system for diagnostic work. The system remains available, but the level of use is low.

CONCLUSIONS

This project has not achieved its aims. The reasons are complex, but mainly relate to human attitudes. Pathologists with excessive workloads were reluctant to use time to learn new skills which were not directed to reducing workload. IT staff did not perceive the project as part of their routine work. There were also numerous technological problems, but although image quality was cited by many, it was not a complaint of those who actively used the system. These problems have not been encountered by previous projects which involved small groups of committed enthusiasts.

Determination of appropriate clomipramine dosage among depressed African outpatients in Dar es Salaam, Tanzania

In an open clomipramine dose finding study, 33 depressed indigenous African outpatients were randomly assigned to two regimens of treatment with 125 mg and 75 mg oral medications daily. At the end of eight weeks of treatment, 16 patients (48.5 pc) were on the 75 mg regime, and 17 (54.8 pc) were on 125 mg. Analysis of depression scores on the Beck-Rafaelsen scale indicated improvements of depression in both regimes of equal magnitude. Analysis of variance showed no statistically significant difference on dose response between the two regimes. The higher doses, however, were associated with more drowsiness and tremulousness. It is suggested that Black African patients respond to tricyclic antidepressants in much lower doses than those recommended in Western textbooks. It is also apparent that side effects of tricyclic antidepressants, which have been implicated in non-compliance to medication, could be avoided without compromising treatment outcome.

Development of methods to analyse transcranial Doppler ultrasound signals recorded in microgravity

During space flights, several clinical syndromes may be the result of changes in cerebral circulation. The purpose of the paper is to describe the development and initial evaluation of a system for recording, processing and displaying transcranial Doppler ultrasound (TCD) waveforms from the middle cerebral artery (MCA) in microgravity. Volunteers were repeatedly subjected to 15-20 s intervals of microgravity ('near zero gravity') during flights on the KC-135 military aircraft. Continuous TCD recordings from the MCA were stored on magnetic tape. The paper describes the system that was developed to digitise the Doppler ultrasound data and markers that corresponded to the various levels of microgravity, obtain the maximum and mean Doppler waveforms, identify the waveforms and quantify them. The results demonstrate the feasibility of making TCD recordings in a microgravity environment and illustrate excellent performance of the system and its ease of operation. Quantitative waveform analysis of the recordings from the first subject studied in the supine position showed statistically significant changes in MCA velocity waveforms during microgravity.

A new pulsatile flow visualization method using a photochromic dye with application to Doppler ultrasound

A nonintrusive method for the visualization of pulsatile flow velocity profiles is described. The method is based on the use of a photochromic dye that is added to the fluid being studied and a nitrogen laser which excites the dye producing a marker "line" whose movement can be photographed. A microcomputer is used as a system controller, to coordinate the system timing and to manage the data transfer. The method used for analysis of the photographs to determine the velocity profiles is described. Examples are presented of instantaneous velocity profiles obtained from velocity waveforms that are similar to those of the femoral artery. In addition, application of the system for studying the relationship between Doppler ultrasound spectral recordings and flow velocity profiles is discussed.

Spectral analysis of Doppler flow velocity signals: assessment of objectives, methods, and interpretation

The objective of this paper is to review the theoretical basis and clinical application of electrical impedance plethysmography in the noninvasive evaluation of peripheral arterial and venous disease. Theoretical, experimental and clinical studies have not demonstrated a direct relationship between electrical impedance changes and limb volume changes. Potential sources of error have also been identified. This has led to the development of clinical tests based on impedance plethysmography for the detection of peripheral arterial disease, venous insufficiency and venous outflow obstruction. Impedance plethysmography, using the method of venous occlusion, is presently the most commonly employed noninvasive method for the detection of deep venous thrombosis.

Comparative study of four methods for quantifying Doppler ultrasound waveforms from the femoral artery

Currently, there is no agreement as to the best method for quantifying Doppler ultrasound recordings from peripheral arteries in order to detect occlusive disease. The four methods assessed in this study are: the pulsatility index, height-width index, path length index, and a Laplace transform function index. Recordings of the Doppler ultrasound spectral waveforms from the common femoral artery of 232 limbs were digitized to obtain the maximum velocity waveforms. This data was analyzed and the various indices were computed and then compared with the arteriographic grades. The effect of distal disease was also examined. The diagnostic accuracy of each index was determined from receiver operating characteristics curves. We concluded that all four indices were capable of detecting significant aortoiliac disease with approximately equal diagnostic accuracy of 90-95% but that pulsatility index had the advantages of simplicity and ease of calculation.

An in vitro model and its application for the study of carotid Doppler spectral broadening

A new in vitro model has been developed for studying the changes in the ultrasound Doppler spectrum that occur in the region of a stenosis. Pulsatile flow in rigid acrylic tubes was produced by means of a modified hemodialysis pump. The Doppler spectral waveforms were measured using a continuous wave Doppler system, a probe of a known field pattern, a real-time high resolution frequency analyzer, and a video display and recording system. The flow velocity waveforms were found to be nearly identical to those seen in the human carotid. Measurements were made to determine the critical stenosis and the results are similar to those reported from in vivo studies. In a preliminary study, the extent of spectral broadening was found to be dependent on the recording site in relation to the stenosis, the severity of the stenosis, and the flow rate. Using qualitative methods it was not possible to determine either the influence of the shape of the stenosis or the phase of the cardiac cycle on spectral broadening.

Relationship between Doppler pulsatility index and direct femoral pressure measurements in the diagnosis of aortoiliac occlusive disease

One hundred and seventy-five aortofemoral segments were studied in order to determine the role of CW Doppler ultrasound combined with real-time spectral analysis in the assessment of aortoiliac disease. The pulsatility index (PI), determined from the maximum velocity waveform, was compared to the systolic pressure difference between the aorta and common-femoral artery as measured at the time of angiography. Receiver operating characteristic curves were constructed and the optimum sensitivities and specificities measured. Results show that if a PI(max) of 5.5 is taken as the threshold level, then the PI is 95% sensitive and specific in detecting hemodynamically significant aortoiliac disease that corresponds to a resting aortofemoral pressure difference of 10 mm Hg or greater. We also carefully examine those technical aspects of Doppler recording and analysis that influence the accuracy of PI measurements.

Problems of carotid Doppler scanning which can be overcome by using frequency analysis

The value of the concomittant use of a real time frequency analyzer along with a continuous wave carotid Doppler scanner is demonstrated in this study of 118 cases. With a colour-coded Doppler scanner alone, internal carotid stenoses greater than 35% were diagnosed with a sensitivity of 95% and a specificity of 82%. With the addition of frequency analysis certain inherent problems with Doppler scanning were overcome and with the measurement of the peak Doppler frequency, the specificity was improved to 93%.

A critical study of ultrasound Doppler spectral analysis for detecting carotid disease

The results of in vitro and in vivo studies to determine the application and limitations of frequency analysis for CW Doppler ultrasound assessment of carotid stenoses are reported. In the in vitro study, the peak Doppler frequency and a new spectral broadening index were determined proximal to, at, and distal to axisymmetric and asymmetrical model stenoses. Good correlations with percent area stenoses were found. In the clinical study, 162 cases were examined using a 4 MHz Doppler system and by standard four-vessel arteriography. Peak frequencies of greater than 3.8 KHz were diagnostic of internal carotid stenoses of 3.2 mm minimum lumen diameter or less, with a sensitivity of 92% and a specificity of 94%. Spectral broadening, evaluated by subjective grading, yielded similar results.

Cerebrovascular assessment using a Doppler carotid scanner and real-time frequency analysis

The results of two methods for noninvasively diagnosing carotid disease are described. In the first study, a color-coded continuous-wave Doppler scanner was used. As evaluated by arteriography in 56 sides, the sensitivity and specificity of the Doppler scanner for diagnosing carotid lesions with greater than 50% stenosis was 71% and 82%, respectively. We found that many of our initial problems could be overcome by the concomitant use of a real-time frequency analyzer. Specifically, when the Doppler waveforms were displayed, we found that: 1) signals that had been attenuated by calcification or plaques, or had reduced velocity as a result of a proximal stenosis, could still be detected; 2) when the velocity of flow was increased to compensate for a contralateral carotid stenosis, the waveforms could still be of diagnostic value; 3) distinguishing between the internal and external carotid arteries was easier than relying on the audio signal alone; 4) when the scan showed internal carotid occlusion, morphological evaluation of the external and common carotid waveforms was helpful in verifying the scan result; and 5) artifactual noise on the Doppler waveform could be recognized. In the second study, frequency analysis recordings were evaluated semiquantitatively by measuring peak frequency and the fractional width of the Doppler frequency spectrum at peak systole Our preliminary results show that this approach is of diagnostic value in that it has the potential to detect minor stenoses.

An automatic, multi-function pressure cuff control unit

A fully automatic blood pressure cuff control system is described. The system is designed for use in the assessment of peripheral vascular disease and helps reduce the amount of operator attention required to carry out such measurements properly. It also provides repeatable control of specific functions, thereby eliminating a potential source of variability. The system incorporates a pneumatic control system, an integrated silicon pressure transducer, and a digital readout. The design, modes of operation, safety features, and use of the system are described.