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Biomedical subjects

T Hess

Publications and source records attributed to T Hess.

At least 73 records · Page 4Linked to original sources
PubMed1994

3D MPRAGE evaluation of lesions in the posterior cranial fossa.

Standard spin-echo images of the posterior cranial fossa are usually impaired by pulsation artifacts. We evaluated a heavily T1 weighted MPRAGE sequence (TR/TE/alpha/TI = 10/4/10-15 degrees/200-350) for detection of intracerebral lesions in the posterior fossa in 11 patients. Overall quality of the MPRAGE images was superior due to the lack of pulsation artifacts, high S/N and excellent gray-white matter contrast. Lesion detection was better in one patient, equal in six and inferior in four patients compared to SE technique. A cerebellar metastasis (8 mm) in one patient was completely blurred from pulsation artifacts on the SE images. Whereas multiple small lesions (< or = 4 mm) with discrete contrast enhancement were missed on the MPRAGE images in three patients. We conclude, that the MPRAGE sequence yields high quality images with isotropic spatial resolution in a reasonable time. But MPRAGE with these parameters can not replace standard SE images in screening the posterior fossa, because of a decreased sensitivity in the detection of small contrast-enhancing lesions.

Adolescent↗
PubMed1994

[A pharmacokinetic analysis of Gd-DTPA enhancement in MRT in breast carcinoma].

Dynamic Gd-DTPA enhanced MR of the breast was performed in one single slice in 27 patients with suspicious nodular lesions. The results could be histologically verified in all cases. A rapid spin-echo sequence with a time resolution of 8.75 s was used for the dynamic examination. The signal changes were analysed using a pharmacokinetic model which allowed parametrization of the contrast enhancement and transformation of the data into colour coded parameter images. The parameters allowed reliable distinction of 9 benign from 18 malignant lesions (p < 0.05 for "amplitude", p < 0.001 for "k21"). One fibroadenoma could not be distinguished from the carcinomas. Lymph node metastases and the pharmacokinetic parameter amplitude correlated significantly (p < 0.05).

Adult↗
PubMed1994

[MR tomography of lung metastases with rapid gradient echo sequences. Initial results in diagnostic applications].

Rapid gradient echo sequences enable MR imaging (MRI) of pulmonary metastases with acquisition times of less than 1 s per slice. By optimization of this technique, density, T1- and T2-weighted images can be obtained (FLASH: TR 6.5 ms, TE2 = 3 ms, alpha = 10 degrees; T1w-Turbo-FLASH: TI 200 ms, TR 6.5 ms, TE2 = 3 ms, alpha = 10 degrees; T2w-Turbo-FLASH: TE1 = 50 ms, TR = 6.5 ms, TE2 = 3.5 ms; alpha = 10 degrees). In a prospective study 25 patients in whom pulmonary metastases were suspected were examined with three techniques in all three anatomical planes prior to surgery. All lung metastases revealed a high signal intensity on the FLASH as well as the T2w-Turbo-FLASH images, whereas vascular structures revealed a low signal intensity on the T2-weighted Turbo-FLASH images. Analysis regarding detection and correct number of lung metastases per patient with MRI compared with the histology revealed (n = 25): sensitivity of 82%, specificity 67%, positive predictive value of 95% and negative predictive value of 33%. While MRI does not currently have any diagnostic advantages over CT, the excellent differentiation of parenchymal lesions and vascular structures without the use of contrast medium and the variability of imaging planes are significant methodological advantages.

Adolescent↗
PubMed1994

[TOF-MR angiography in radiotherapy treated cerebral arteriovenous malformations].

Intracerebral arteriovenous malformations represent congenital anomalies with an arteriovenous shunt (nidus). The therapeutic goal is to eliminate the risk of bleeding and to improve the clinical symptoms. The exact localization of the nidus and the identification of the feeding arteries are critical for therapy planning. Up to now conventional brain angiograms have been used for treatment planning and for the assessment of therapy response. We studied whether 3D time-of-flight (TOF) MR angiography can be used for therapy planning and monitoring. MRI and TOF-MRA studies of 28 patients undergoing radiotherapy were evaluated. They were compared to conventional angiography to assess the MRA study. A Correct identification of the arterial feeder and the nidus was possible in about 75% of the patients. In combination with the MRI study, an important 3D dataset for treatment planning could be obtained that includes therapeutically relevant information on the localization and spatial structure of the AVM as well as the adjacent brain tissue. As a noninvasive technique, close-meshed follow-up studies could be performed with MRA.

Adolescent↗
PubMed1994

[Intramedullary pressure in the femur during boring and nailing with modern compression interlocking nails--risk of fat embolism?].

Fat embolism syndrome occurs in only 0.9-4% of patients with long bone fractures and especially with intramedullary nailing. Earlier publications have shown that intramedullary manipulation, e.g. reaming and nailing, can produce high pressures of up to 1 bar. The design of the new non-slotted interlocking compressions nails seems to increase the pressure in the femoral cavity. We measured the intramedullary pressure during reaming of the marrow cavity and insertion of compression nails (OSTEO), using cadaver femora and a piezo pressure transducer. We simulated a proximal fracture and performed 30 drilling and 20 nailing procedures. On average we detected a maximum pressure of 0.26 bar during drilling and 0.63 bar during nailing. During reaming the pressure increased when the reamer had passed the narrow diaphysis and reached the metaphysis. When the tried to enlarge the femoral canal by pushing and pulling the reamer repeatedly we measured high pressure peaks. During nailing we detected short impulses lasting a few milliseconds. The results show that the new compression nail do not produce higher intramedullary pressure than slotted nails. It is possible to avoid a dangerous pressure level by using a careful operative technique.

Biomechanical Phenomena↗
PubMed1994

[Systemic thinking in school psychology and education].

Public school counseling facilities have put up much resistance against the integration of systemic-psychological principles and methods into their professional field, despite the many critical reviews of their traditional counseling methods. Unlike the progressive changes and reforms which have taken place in various other institutions for children and teenagers, very few methodological changes have come forth within the field of school counseling. A serious consideration of the many proposed suggestions based upon systemic-psychological principles is long overdue. The author illustrates in this article two major trends of thought within the field of systemic psychology (the structuralistic and constructivistic schools). After highlighting the differences between these two schools, the author goes on to discuss the invariable consequences of the integration of the respective systemic methods into the traditional educational counseling programs. The emphasis has been placed upon the constructivistic school of thought, backed by provocative theses and exemplary case studies. Based upon his own practical experience the author has come to realise in this field, that systemic intervention is less time-costly than traditional school-psychological testing. For this reason, he is optimistic that a modification of traditional school counseling/psychology will come in due time. Such modification would also be sure to incite new creative interest and a greater desire for experimentation amongst the school counselors and school psychologists, not to mention a more adequate education for ongoing counselors and psychologists in this particular field.

Adolescent↗
PubMed1994

Lateral tibial avulsion fractures and disruptions to the anterior cruciate ligament. A clinical study of their incidence and correlation.

Avulsion fractures of the lateral tibial plateau, known as the lateral capsular sign, are increasingly associated with anterior cruciate ligament (ACL) ruptures. This phenomenon, known as the Ségond fracture, is a bony avulsion of the menisco-tibial ligament. Stress, which can lead to an avulsion of this kind, almost always occurs during knee flexion and internal tibial rotation, and in most cases only after damage to the primary ACL stabilizer. Examination of 151 ACL ruptures revealed a Ségond fracture in 9% of patients. Nearly all were caused by sports injuries and, understandably, the accident mechanism always included knee flexion and internal rotation of the tibial. In a similarly large number of other knee injuries without damage to the ACL, only one case of a Ségond fracture was found. This phenomenon, which is easy to detect by radiograph, can thus be regarded as a strong indication of the presence of a ligament injury.

Anterior Cruciate Ligament Injuries↗
PubMed1993

['Cardiac ballet' with and without amiodarone].

Two well documented cases of torsades de pointes under amiodarone therapy are discussed. This special form of ventricular tachycardia is also known as "twisting around the points" or "cardiac ballet". Our first case involves recurrent torsades de pointes manifesting almost 2 weeks following onset of amiodarone therapy. They were successfully treated by overpacing. In the second case the isolated torsade de pointes was probably not caused by the longlasting and successful use of amiodarone but reflected severe ischemic heart disease and slight hypokalemia. This was confirmed in the one year follow-up, as torsade de pointes was no longer present despite increased dosage of amiodarone. Amiodarone-induced torsades de pointes is very rare. Most cases reported in the literature are poorly documented or were caused by other factors (electrolyte disturbances, other antiarrhythmic medication). If amiodarone has been administered as a matter of utmost necessity, other etiologies must be excluded or eliminated before amiodarone therapy is stopped when torsades de pointes occurs. Torsade de pointes due to amiodarone arises independently of the duration of therapy, the administered dosage and the extent of QT-prolongation. Holter monitoring does not allow a prediction and the benefit of electrophysiological studies is still controversial. The management of patients with amiodarone-induced torsades de pointes includes administration of magnesium and, frequently, overpacing. Due to the long half-life of amiodarone, prolonged temporary pacing may be required. General experience suggested that amiodarone can be used safely in patients who have developed torsades de pointes with other agents.

Aged↗
PubMed1993

Recurrent rectal cancer: diagnosis with dynamic MR imaging.

PURPOSE: To evaluate whether dynamic magnetic resonance (MR) imaging can increase the diagnostic accuracy in suspected local recurrence of rectal carcinoma. MATERIALS AND METHODS: Eighteen patients (seven men, 11 women, aged 26-78 years) with 19 suspect lesions were examined. T1-weighted (pre- and postcontrast) and T2-weighted spin-echo images were read by three observers. Computed tissue-specific enhancement parameters were obtained and displayed on gray-scale images (pharmacokinetic mapping). RESULTS: Reading of the spin-echo images yielded a sensitivity of 91%-100% (confidence interval, 67%, 100%), a specificity of 29%-43% (12%, 67%), and an accuracy of 71%-75% (48%, 91%). Analysis of the MR data showed greater (P = .0038) and faster (P = .0018) enhancement of malignant lesions (n = 12) compared with benign lesions (n = 7). CONCLUSION: Pharmacokinetic mapping of dynamic MR imaging data allows in vivo insight into tissue physiopathology, helping differentiate benign from malignant pelvic lesions in rectal cancer.

Adult↗
PubMed1993

[Sleep apnea].

Regular and unobstructed breathing during the night is the prerequisite for an undisturbed and restful sleep. The most prevalent nocturnal breathing disturbance with morbid consequences is the obstructive sleep apnea syndrome. Forms severe enough to need therapy and, therefore, a thorough work-up, can be usually detected by a detailed history. Pathophysiology, clinical findings, differential diagnosis as well as work-up and therapy of the sleep apnea syndrome are discussed.

Airway Obstruction↗
PubMed1993

[Magnetic resonance spectroscopy of breast cancer].

Conservative therapeutic concepts with initial chemotherapy for patients with breast cancer represent a challenge to non-invasive techniques for monitoring response to therapy. Experimental magnetic resonance spectroscopy studies have been able to show exemplary applications for therapy monitoring of breast cancer patients. The characteristic phosphomonoester resonances and their changes during therapy are possible clinical parameters. The additional information which can be obtained from proton and carbon spectroscopy increases the amount of detectable metabolites. On-going studies are investigating clinical applications of multinuclear spectroscopic studies in patients with breast cancer.

Breast Neoplasms↗
PubMed1992

[Significance of bronchial alveolar lavage in the diagnosis of eosinophilic pneumonia].

We describe 3 cases of eosinophilic pneumonia of unknown etiology with atypical clinical findings diagnosed by bronchoalveolar lavage (BAL). In 2 patients with subacute symptoms and restrictive ventilatory dysfunction there was no eosinophilia in peripheral blood, and chest X-ray showed a bilateral acinar and mixed interstitial-acinar pattern respectively. Transbronchial lung biopsies revealed only nonspecific changes. The third patient had acute respiratory failure and the eosinophils in peripheral blood were 1500/microliters. Chest X-ray demonstrated only minimal interstitial changes. In all instances the eosinophilic pneumonia was diagnosed by a marked BAL-eosinophilia of 25 to 45%. No specific etiology could be detected for the eosinophilic lung disease. The response to treatment with corticosteroids was prompt.

Aged↗
PubMed1992

[Pneumocystis carinii pneumonia in HIV-negative immunosuppressed patients].

During a period of 10 years 129 immunosuppressed HIV-negative patients were evaluated for pulmonary complications. A definite diagnosis could be established in 72 cases (56%): Pneumocystis carinii pneumonia (PCP) (25), pulmonary involvement of underlying disease (10), drug toxicity (8), mycobacterioses (6), bacterial pneumonias (5), aspergillosis (5), others (13). The underlying conditions in patients with PCP were: lymphatic neoplasias (11), immunosuppression after solid organ (9) and after bone marrow transplantation (3), cytotoxic therapy for lupus erythematodes (1) and carcinoma (1). In 8 of 9 transplant patients anti-rejection therapy preceded the episode of PCP. Six patients (24%) died from respiratory failure 1 to 25 days after diagnosis of PCP, despite mechanical ventilation in four. Two patients recovered completely after mechanical ventilation for 14 and 30 days respectively. The frequency of PCP has markedly increased during the last few years: 1981-1987: 2 cases (6%), 1988: 4 (14%), 1989: 8 (42%) and 1990: 11 (26%). This can hardly be explained by improved diagnostic sensitivity or an increased number of immunosuppressed patients. Apart from the use of more potent immunosuppressive agents, the increased prevalence of Pneumocystis carinii may play an important role.

Adolescent↗
PubMed1992

Serial chest thumps for the treatment of ventricular tachycardia in patients with coronary artery disease.

Based on excellent results of successive single chest thumping (CT) and serial chest thumping (SCT) for the interruption of ventricular tachycardia (VT) in experimental animals with subacute myocardial infarction, the SCT method was applied for the treatment of VT in patients with coronary artery disease (CAD). SCT was successful in terminating 13 of 19 episodes of VT (68%) in 8 of 14 patients (57%). Conversion of VT was immediate in 9 episodes in 6 patients and latent in 4 episodes in 2 patients. Complications were rare but significant. In one case, SCT resulted in a ventricular asystole and in another case SCT accelerated the rate of VT from 167/min to 242/min, requiring electroconversion. Neither a short duration of VT nor a preserved left ventricular function seemed to enhance conversion by SCT. For interruption of VT in patients with CAD, SCT is not as successful as in the experimental animal model and, therefore, should not be used as a routine method. It may be applied in selected patients under hospital conditions with a standby defibrillator.

Adult↗
PubMed1992

Prospective evaluation of a prognostic score for Pneumocystis carinii pneumonia in HIV-infected patients.

Serum lactate dehydrogenase levels, alveolar-arterial oxygen gradient, and percentage of neutrophils in bronchoalveolar lavage correlate most strongly with early mortality in Pneumocystis carinii pneumonia (PCP) in HIV-infected patients. However, the individual outcome can not be predicted by these parameters due to a considerable overlap between survivors and nonsurvivors. We prospectively investigated a PCP severity score, which has been developed earlier based on a retrospective analysis. Seven of 94 consecutively examined HIV-infected patients died within 14 days after diagnosis of PCP. A PCP severity score greater than 7 had a positive predictive value for early fatal outcome of 66.7 percent (6/9) and a negative predictive value of 98.8 percent (84/85). The overall diagnostic accuracy was 95.7 percent (90/94). The positive predictive value for early fatal outcome of a P(A-a)O2 > 35 mm Hg was 24 percent (6/25); the negative predictive value was 98.6 percent (68/69). However, the overall diagnostic accuracy was only 78.7 percent (74/94). The PCP severity score is a valuable tool for clinical decision making, for the early identification of patients with a prognostic unfavorable course, and for the comparison of patient populations in future studies of HIV-associated PCP.

AIDS-Related Opportunistic Infections↗
PubMed1992

Diagnostic value of hemosiderin-containing macrophages in bronchoalveolar lavage.

STUDY OBJECTIVE: Our objective was to determine if the hemosiderin content of BAL macrophages allows us to draw any differential diagnostic conclusions in a variety of lung diseases. PATIENTS AND STUDY DESIGN: One hundred one patients who underwent BAL for different diagnostic reasons were studied prospectively. MAIN RESULTS: The highest values for the hemosiderin score (HS) were found in patients with active alveolar hemorrhage and patients who had undergone heart transplantation for congestive heart failure. Compared to a control population, patients with Pneumocystis carinii pneumonia or invasive aspergillosis had a higher HS than patients with bacterial pneumonia or mycobacterial lung infection. High or intermediate values for HS were more often found in patients with a low than in those with a normal platelet count. CONCLUSIONS: The differential diagnostic conclusions which can be based on an HS are limited.

Adolescent↗
PubMed1992

[The value of the localization technique of occult breast changes with reference to future screening programs].

A retrospective study of 54 needle localisations of occult mammographic lesions by the technique of Brun del Re shows an easy and precise handling of the method without serious complications and emphasizes the favourable result of the localized breast cancers (a lot of non-invasive cancers, small average size of the cancers, most cases with nodal negative state). Our results are compared to a literature review. The discussion demonstrates the importance of localisation techniques in the set-up of screening programs.

Biopsy, Needle↗