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Biomedical subjects

C A Carlsson

Publications and source records attributed to C A Carlsson.

At least 19 recordsLinked to original sources
PubMed1999

Imaging modalities in x-ray computerized tomography and in selected volume tomography.

This review of different principles used in x-ray computerized tomography (CT) starts with attenuation (transmission) CT. The pros and cons of different geometrical solutions, single-ray, fan-beam and cone-beam, are discussed. Attenuation CT measures the spatial distribution of the linear attenuation coefficient, mu. The contributions of different interaction processes to mu have also been used for CT. Fluorescence CT is based on measurements of the contribution, cZtauZ/rho, from an element Z with concentration cZ, to the linear attenuation coefficient. Diffraction CT measures the differential coherent cross section d sigma (theta)(coh)/d omega, Compton CT the incoherent scatter cross section sigma. The usefulness of these modalities is illustrated. CT methods based on secondary photons have a competitor in selected volume tomography. These two tomography methods are compared. A proposal to perform Compton profile tomography is also discussed, as is the promising method of phase-contrast x-ray CT.

Algorithms↗
PubMed1997

Long-lasting cervical radicular pain managed with surgery, physiotherapy, or a cervical collar. A prospective, randomized study.

STUDY DESIGN: This prospective, randomized study compares the efficacy of surgical and conservative treatments in patients with long-lasting cervical radicular pain. OBJECTIVES: To compare the effects of surgery, physiotherapy, and a cervical collar. SUMMARY OF BACKGROUND DATA: There are no previous controlled outcome studies that have compared surgical treatment with nonsurgical treatment of patients with cervical radicular pain. METHODS: The study group comprised 81 patients with cervicobrachial pain of at least 3 months' duration, in whom the distribution of the arm pain corresponded to a nerve root that was significantly compressed by spondylotic encroachment with or without an additional bulging disc, as verified by magnetic resonance imaging or computed tomographic myelography. The patients were randomly allocated to surgery (Cloward technique), individually adapted physiotherapy, or a cervical collar. The therapeutic effects were evaluated with respect to pain intensity by the visual analogue scale, function by the Sickness Impact Profile, and mood by Mood Adjective Check List. The measurements were performed before treatment (control 1), shorter after treatment (control 2), and after a further 12 months (control 3). RESULTS: At control 1, the groups were uniform. At control 2, the surgery group reported less pain (visual analogue scale) and, like the physiotherapy group, better function (Sickness Impact Profile) than the collar group. At control 3, there was no difference in visual analogue scale, Sickness Impact Profile, and Mood Adjective Check List measurements among the groups. CONCLUSIONS: In the treatment of patients with long-lasting cervical radicular pain, it appears that a cervical collar, physiotherapy, or surgery are equally effective in the long term.

Adolescent↗
PubMed1997

Cervical radiculopathy: pain, muscle weakness and sensory loss in patients with cervical radiculopathy treated with surgery, physiotherapy or cervical collar. A prospective, controlled study.

This prospective, randomised study compares the efficacy of surgery, physiotherapy and cervical collar with respect to pain, motor weakness and sensory loss in 81 patients with long-lasting cervical radiculopathy corresponding to a nerve root that was significantly compressed by spondylotic encroachment, with or without an additional bulging disk, as verified by MRI or CT-myelography. Pain intensity was registered on a visual analogue scale (VAS), muscle strength was measured by a hand-held dynamometer, Vigorometer and pinchometer. Sensory loss and paraesthesia were recorded. The measurements were performed before treatment (control 1), 4 months after the start of treatment (control 2) and after a further 12 months (control 3). A healthy control group was used for comparison and to test the reliability of the muscle-strength measurements. The study found that before start of treatment the groups were uniform with respect to pain, motor weakness and sensory loss. At control 2 the surgery group reported less pain, less sensory loss and had better muscle strength, measured as the ratio of the affected side to the non-affected side, compared to the two conservative treatment groups. After a further year (control 3), there were no differences in pain intensity, sensory loss or paraesthesia between the groups. An improvement in muscle strengths, measured as the ratio of the affected to the non-affected side, was seen in the surgery group compared to the physiotherapy group in wrist extension, elbow extension, shoulder abduction and internal rotation, but there were no differences in the ratios between the collar group and the other treatment groups. With respect to absolute muscle strength of the affected sides, there were no differences at control 1. At control 2, the surgery group performed some-what better than the two other groups but at control 3 there were no differences between the groups. We conclude that pain intensity, muscle weakness and sensory loss can be expected to improve within a few months after surgery, while slow improvement with conservative treatments and recurrent symptoms in the surgery group make the 1-year results about equal.

Adult↗
PubMed1997

Hidden compartments in AVMs--a new concept.

PURPOSE: The concept of hidden compartments in cerebral arteriovenous malformations (AVMs), which is hereby launched, offers a new explanation for the neurosurgical and neuroradiological controversies concerning patients with AVMs. MATERIAL AND METHODS: Three patients who were considered completely cured of their AVMs, subsequently developed new areas of malformed vessels as revealed by later angiograms. RESULTS: These 3 cases support our hidden compartment hypothesis and are reported on here, illustrated with relevant angiograms. The clinical implications of the hidden compartment concept refer to phenomena such as AVM growth, AVM recurrence after surgical excision, irradiation or embolization as well as per- or postoperative hemorrhage and swelling. CONCLUSION: The incidence of hidden compartments in the AVM population is unknown but further studies, particularly in the realm of superselective embolization, could reveal their presence.

Adult↗
PubMed1995

Methodologic aspects of computed microtomography to monitor the development of osteoporosis in gastrectomized rats.

RATIONALE AND OBJECTIVES: We investigated the methodologic development of computed microtomography (CMT) for monitoring the development of osteoporosis in male Sprague-Dawley rats. METHODS: Eight rats were gastrectomized and eight rats were sham operated. Femurs, tibias, and tails were prepared, and CMT scans with spatial resolutions of 5-500 microns were made. Bone diameters, bone areas, and moments of inertia were determined from the CMT scans. Optimal slice position and the need for spatial resolution and energy optimization for future in vivo applications were investigated. RESULTS: Gastrectomy caused dramatic changes in the bone architecture of the tibia and the femur. The main features were vacuolization of the bone and reduced amounts of compact bone. Although the outer diameters of tubular bones (femur and tibia) were largely unaffected, their inner diameters were greatly increased following gastrectomy. Relative bone area and moment of inertia were greatly reduced. The optimal photon energy was 12 keV. CONCLUSION: It is possible to monitor gastrectomy-evoked changes in bone morphology at various sites in rats using CMT scanning. The changes are suggestive of osteoporosis. By optimizing the energy spectrum and spatial resolution, as well as choosing the proper slice position, it should be possible to keep absorbed doses low enough to avoid acute radiation injury in repeated in vivo measurements.

Animals↗
PubMed1994

Shaping X-ray spectra with filters in X-ray diagnostics.

The influence on image contrast, tube load and patient mean absorbed dose of different ways of shaping diagnostic X-ray spectra by placing filters in the beam is derived fro two radiographic models (abdominal screen-film radiography and intra-oral, dental radiography) using a computational model. The filters are compared at either equal tube load (keeping tube potential constant) or equal contrast (adjusting the tube potential with the different filters), but always at equal energy imparted per unit area to the image receptor. Compared at equal tube load and relative to standard aluminum filtration, reductions in the mean absorbed dose in the patient of 15-25% can be achieved using filters of Cu, Ti, W and Au (increasing the tube load by 30-40% compared with standard aluminium filtration). However, contrast is also reduced by 7%. Compared at equal contrast, the dose reductions are smaller, about 10%. Filters of copper are generally recommended, as are filters of aluminium. The use of bandpass filters (K-edge filters) should be restricted to examinations where the need for substantial variation in tube potential from patient to patient is small. The benefit of using thicker filters than those commonly used today (increasing tube load by factors of 1.4-2.0 compared with no added filter) is small as the dose reduction is most rapid for small initial values of added filters, and the increase in tube load increases steadily with increasing filter thickness.

Humans↗
PubMed1993

Cellular differentiation: a theory based on simulation with computer graphics.

Rules are outlined in order to construct graphically a computer model that deals with cell growth, multiplication and differentiation. The process starts with a multicoloured stem cell and the end product will be differentiated cells represented by different colours. Various biological processes and neoplastic transformation can also be simulated. Based on the idea that the model corresponds to real events, predictions are made about the possible results of future experiments.

Animals↗
PubMed1989

The neurogenic overactive bladder. Classification based on urodynamics.

The aetiology and pathogenesis of bladder overactivity are very variable and the classification is rather crude. By careful interpretation of clinical findings and urodynamic assessments, refinement of the diagnosis is possible. From a therapeutic and prognostic stand-point, it is of interest to distinguish between "idiopathic detrusor instability" and the "uninhibited overactive bladder". Based on neurological investigation and cystometric recordings, including the ice water test, characteristics of the 2 entities are described.

Adult↗
PubMed1988

Epidural spinal electrical stimulation in severe angina pectoris.

The short term effects of epidural spinal electrical stimulation were studied in 10 patients with angina pectoris of New York Heart Association functional class III or IV. The antianginal pharmacological treatment given at entry to the study was regarded as optimal and was not changed during the study. The effects of epidural spinal electrical stimulation were measured by repeated bicycle ergometer tests. Treatment with epidural spinal electrical stimulation increased the patients' working capacity, decreased ST segment depression, increased time to angina, and reduced the recovery time. The observed effects did not seem to be correlated with any changes in myocardial oxygen demand during epidural spinal electrical stimulation and were additional to the benefits of the pharmacological treatment.

Aged↗
PubMed1987

Surgical and conservative treatment of cervical spondylotic radiculopathy and myelopathy.

One hundred and fourteen patients were admitted to our department for evaluation of their cervical spondylogenetic symptoms, including local cervical pain, radiculopathy and myelopathy. This retrospective study gives the results, expressed as improved, unchanged or worse, of anterior surgery, posterior surgery and conservative treatment. Local cervical pain improved in about half of the patients, without any difference between the groups. The effect of surgery on radiculopathy was superior to that of conservative treatment, 71 percent and 74 percent respectively, being improved after anterior and posterior surgery, compared to 19 percent in the conservatively treated group. The majority of patients with myelopathy were treated with posterior surgery and 69 percent had improved. The results were not influenced by the patients age or the duration of symptoms. It is argued that the positive effects of surgery on the radiculopathy are due to a segmental stabilisation rather then to decompression. The immediate post-operative improvement of the myelopathy is undoubtedly caused by the decompression while the long-termed improvement cannot with certainty be attributed to the operation.

Adult↗
PubMed1987

Long-term results by epidural spinal electrical stimulation (ESES) in patients with inoperable severe lower limb ischaemia.

Arterial reconstruction is the treatment of choice for patients with severe lower limb ischaemia, but may at times be technically impossible. Thirty-two consecutive patients with impending (n = 24) or already established (n = 8) distal arteriosclerotic or diabetic lower limb gangrene, in whom vascular surgery was either technically impossible or had failed, were treated with epidural spinal electrical stimulation (ESES) for 27 +/- 16 (S.D.) months. All patients had severe rest pain, which was reduced by ESES in 91% of the cases. Improved ulcer healing was noted in 58% of the patients who had skin ulceration. Eighty-three percent of those patients who did not have established gangrene when ESES was started, retained their leg after 1 year, and 54% after 3 years. These results suggest that ESES often provides pain relief and improves skin healing in patients with impending arteriosclerotic or diabetic gangrene in whom vascular surgery is impossible or has failed. Epidural spinal electrical stimulation (ESES) does not affect the progression of established gangrene but may provide pain relief. The observed outcome of severe limb ischaemia in this study could be used to compare with those after arterial reconstruction performed in patients with poor run-off vessels, and may allow us to examine the natural history of this disease when adequate pain relief is provided. The results reported here and the previously reported enhancement of cutaneous blood flow in severely ischaemic extremities by ESES may suggest, that ESES enhances limb salvage by improving skin blood flow.

Aged↗
PubMed1987

Treatment of spinal cord injuries in the thoracolumbar region.

Forty patients with spinal cord injuries in the thoracolumbar region were studied. Clinical and experimental data support the conservative approach. In some patients acute stabilisation is needed and in a few patients operative decompression may be considered. Promising experimental non-invasive techniques to improve recovery are presented, but there are no convincing clinical results so far. The authors believe that regeneration will be the key area for future research.

Early Ambulation↗
PubMed1986

Contelle: pelvic floor stimulator for female stress-urge incontinence. A multicenter study.

The clinical efficacy of a new device for treatment of female incontinence was studied in a multicenter trial. The device consists of an inflatable electrode carrier and an external stimulator unit. Forty women were treated: 10 had primary or recurrent genuine stress incontinence, 15 had urge incontinence due to idiopathic detrusor instability, not responding to drug treatment, and 15 had stress incontinence combined with detrusor instability. Twenty-five patients were improved by the treatment. Another 8 reported an excellent result of treatment and remained free of symptoms for more than six months after withdrawal of the treatment. The results were more favorable in patients with bladder hyperactivity than in genuine stress incontinence. The patients' general ratings of treatment efficacy correlated well with their recordings of urinary frequency and consumption of incontinence pads. The functional bladder capacity increased in improved patients, but normalization of urodynamic parameters was no prerequisite for clinical improvement. We found intravaginal electrical stimulation to be a valuable alternative to medical and surgical intervention in patients with detrusor instability.

Adult↗
PubMed1986

Generalised use of contrast degradation and contrast improvement factors in diagnostic radiology. Application to vanishing contrast.

Although field area and object thickness are important parameters in comparisons of techniques for optimal reduction of scattered radiation to the image, they are in practice seldom varied. For this reason, we suggest that contrast degradation (CDF) and contrast improvement (CIF) factors be more frequently used and appropriately defined to make the dependence of CDF and CIF on field area (collimation) and object thickness (compression) explicit. Definitions are formulated and the results of experiments and Monte Carlo calculations (comprising effects of collimation, compression, air gap, antiscatter grid, detector thickness) cited to illustrate their usefulness. Currently used expressions for CIF (derived assuming monoenergetic radiation) lack a factor to account for the change in primary contrast caused by the antiscatter method when this affects the energy distribution of the transmitted primary photons (grids and compression) or the fractions of photon energy imparted to the detector (when comparing different detectors). Values of this factor are calculated for some cases. Also, the appropriate choice of physical quantity to be used in the formulae for CDF and CIF is discussed. The energy imparted to the detector is advocated since this is directly related to the detector signals forming the image on, e.g. the x-ray film.

Humans↗
PubMed1986

Relations between effective dose equivalent and mean absorbed dose (energy imparted) to patients in diagnostic radiology.

Values of HE/D, the ratio of the effective dose equivalent HE to the mean absorbed dose D to the total body, have been derived as a function of beam quality (HVT) for a variety of Roentgen diagnostic examinations of the adult trunk and head, using tabulations from the literature. Problems in specifying beam quality are discussed. The energy epsilon imparted to the patient can, in Roentgen diagnostic examinations, be determined using a transmission chamber. Since, however, HB/epsilon depends more critically than HE/D on the mass M of the patient (D = epsilon/M), the latter quantity is preferred for risk assessment. HE/D takes values in the range 0.44-2.8 Sv Gy-1. This includes the value 1 Sv Gy-1 resulting from a uniform whole-body irradiation independent of M. The corresponding value of HE/epsilon = 1/M Sv J-1 if M is in kg. It is therefore recommended that clinical measurements of epsilon be supplemented by measurements of the patient's mass so that D = epsilon/M can be estimated and tabulations of organ absorbed doses be supplemented with values of D so as to allow accurate derivation of the ratio HE/D. In optimising the technical parameters of a given examination using the transmission chamber, HE/D as a function of beam quality must be known.

Humans↗
PubMed1986

Serum immunocomplexes in patients with subarachnoid hemorrhage.

Immunocomplexes (IC) in serum were analyzed in 54 patients with subarachnoid hemorrhage (SAH) from ruptured arterial aneurysms. A previous study had shown that patients with SAH and vasospasm had a significantly higher incidence of ICs in the blood than patients without vasospasm. The aim of the present study was to study how the IC content varied with time and compare this pattern with the clinical picture. Forty-two patients presented clinical or radiological signs of cerebral vasospasm during their hospital stays, whereas 12 patients showed no such signs. The patients with vasospasm had a significantly higher amount of ICs in serum than those without vasospasm. In 37 patients with vasospasm, the changes of IC content during the 1st weeks after SAH correlated well with the clinical course. Data indicated that a high IC content preceded the onset of vasospasm and a low content preceded clinical improvement. This observation supports the idea that the presence of ICs might be the cause and not the result of vasospasm.

Adult↗
PubMed1985

Epidural electrical stimulation in severe limb ischemia. Pain relief, increased blood flow, and a possible limb-saving effect.

Peripheral vascular disease of the extremities causes ischemic pain and, at times, skin ulcerations and gangrene. It has been suggested that epidural spinal electrical stimulation (ESES) could improve peripheral circulation. Since 1978 we have used ESES in 34 patients with severe limb ischemia; all had resting pain and most had ischemic ulcers. Arterial surgery was technically impossible. Twenty-six patients had arteriosclerotic disease, one had Buerger's disease, and seven had severe vasospastic disorders. Ninety-four per cent of the patients experienced pain relief. ESES healed ulcers in 50% of those with preoperative nonhealing skin ulcerations. Seventy per cent of the patients showed improved skin temperature recordings. Only 38% of the stimulated arteriosclerotic patients underwent amputations during a mean followup period of 16 months, as compared to 90% of a comparable group of unstimulated patients. ESES is very promising in severe limb ischemia where reconstructive surgery is impossible or has failed.

Adult↗