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C F Hess

Publications and source records attributed to C F Hess.

At least 73 records · Page 4Linked to original sources
PubMed1988

[Reproducibility of the sonographic determination of the size of intra-abdominal space-occupying lesions].

The reproducibility of sonographic measurements was checked using 255 measurements on 57 intra-abdominal masses. It was shown that differences of measurements carried out independently by two observers increased in a linear manner with tumour diameter. Relative differences in measurement averaged 10%, but in 5% of cases they reached 30%. Somewhat better results were obtained with small tumours and for measurements lying strictly in the axis of the body. The significance of these findings in clinical practice, particularly for tumour follow-up, is discussed.

Abdominal Neoplasms↗
PubMed1988

Small arteries in peripheral lymph nodes: a specific US sign of lymphomatous involvement.

Fifty-seven patients with palpably enlarged peripheral lymph nodes underwent detailed ultrasonographic (US) examination with a 5.0-MHz and a 7.5-MHz probe. In 32 of 36 patients with malignant lymphoma (12 with Hodgkin disease, 24 with non-Hodgkin lymphoma) US showed a hypoechoic mass with a centrally located tubular structure. Pathologic examination showed that this structure correlated with small intact arterial vessels encased by confluent lymphomatous masses. This sonographic finding was not seen in patients with carcinomatous metastatic lesions to the lymph nodes (nine patients) or benign lymphadenitis (12 patients). The detection with US of small arteries within enlarged lymph nodes may indicate nodal infiltration by malignant lymphoma.

Arteries↗
PubMed1987

[1st results of the diagnosis of focal liver and spleen lesions using gradient echo sequences].

15 healthy subjects and 39 patients with focal liver and spleen lesions were examined via MR tomography at 1.5 tesla. Gradient field echos at small angle excitation (less than 90 degrees) were employed. The imaging time per layer was 10 seconds so that rapid imaging could be carried out at respiratory standstill. This enabled visualisation of liver and spleen without interference by breathing artifacts and with accurate localisation. Focal lesions can be imaged best at low flip-angle pulses (liver) or low to medium-angle pulses (spleen). The primary liver cell carcinoma is visualised as an inhomogeneous structure with similar signal intensity as the surrounding tissue. All other examined liver lesions (metastases, haemangiomas, lymphatic infiltrates, echinococcus cysts, FNH, gummae) showed greater signal intensity than the remaining organ at small angle excitation. Furthermore, contrast reversals were seen at medium-angle pulses. Contrariwise, with the exception of the light-coloured spleen infarcts, spleen lesions (lymphatic infiltrate, Boeck's disease or sarcoidosis) appeared darker at all excitation angles than the surrounding tissue.

Humans↗
PubMed1987

[Focal changes in the spleen. Ultrasonic morphological characteristics and their clinical significance].

Focal changes in the spleen were rare findings in a large clinical material (less than 1% of cases). In a prospective study, which included 580 patients, lesions in the spleen were found in 40. Four focal lesions were due to infiltrates from non-Hodgkin's lymphoma. Twenty-one lesions with low echoes consisted of twelve infiltrates from Hodgkin's disease (six patients) or non-Hodgkin's lymphoma (six patients), five were due to fresh splenic infarcts and one each to an abscess, a metastasis from a carcinoma of the stomach, sarcoid and a haemorrhage. In only three of ten highly echogenic foci was a diagnosis possible (one leukaemic infiltrate and two scars following splenic infarcts). The significance of the sonographic demonstration of focal splenic lesions for diagnosis and treatment is discussed. The advantages of a sector scanner for evaluation of the spleen and splenic size are mentioned.

Hodgkin Disease↗
PubMed1987

[The internal echo pattern of the normal pancreas. An assessment of the aging process and body weight dependence by sonographic gray-scale analysis].

Sonography of the pancreas was evaluated quantitatively in 94 normal subjects. The grey-scale values in the head and body of the pancreas were measured and compared with those of retroperitoneal fat. The echogenicity of the pancreas and the contrast between pancreas and fat were correlated with the age and weight of the subjects. Semi-quantitative studies revealed a positive correlation between echogenicity and age (r = 0.505); this can be confirmed to a high degree of statistical significance by quantitative analysis of pancreatic grey-scale values (r = 0.55 for the head and 0.71 for the body). Further improved correlation with age is obtained by computing the sonographic contrast between the pancreas and the retroperitoneal fat (r = 0.66 for the head and 0.77 for the body of the pancreas). It is concluded that determination of the grey-scale value can provide additional information particularly if one uses retroperitoneal fat as a reference tissue.

Adipose Tissue↗
PubMed1986

[Imaging of prostatic cancer by 1.5 Tesla nuclear resonance tomography].

Twenty-two patients with histologically confirmed carcinomas of the prostate were examined by nuclear magnetic resonance, using a 1.5 Tesla magnet (stage T1: one patient, T2: eight patients, T3: six patients, T4: seven patients). In 19 out of the 21 patients in stages T2 to T4, the tumour showed a specific signal intensity. In 12 cases, the tumour signal was more intense than from a normal prostate when using medium repetition and echo delay times; in 19 cases, multi-echo sequences with increasing echo delay time (30 to 240 ms) and long repetition times (usually 1600 ms) showed less reduction in signal intensity than surrounding structures (except urine). Unlike computed tomography, 1.5 Tesla MR is able to demonstrate carcinomas confined to the prostate. Demonstration of infiltration is possible with MR with great accuracy because of the ability to obtain images in three planes and because of the accurate rendering of soft tissue detail. In particular, MR differentiates between stages T2 and T3 more clearly than does CT. The best demonstration of anatomical structures in the true pelvis is achieved with a repetition time of 800 ms and an echo delay time of 30 ms, the best demonstration of tumour with corresponding 1600 ms and 120 ms. The effect of catheters in the bladder, or previous transurethral resection on the MR images is discussed.

Aged↗
PubMed1986

[Subjective evaluation and quantitative gray-scale analysis in the sonographic diagnosis of diffuse changes in the liver parenchyma].

Two investigators were asked to evaluate independently the echogenicity, coarsening and inhomogeneity of the hepatic echo pattern in a semi-quantitative manner; they had no knowledge of the diagnosis and used the same apparatus. The three subjective criteria were largely independent from the observer. Approximately three-quarters of all patients with slightly increased echogenicity showed a subjective appearance of coarsening; the impression of inhomogeneity increased significantly with increasing echogenicity. This is of importance in the sonographic evaluation of cirrhosis of the liver and in the diagnosis of diffuse liver metastases in a fatty liver. Grey scale analysis within a region of interest showed satisfactory correlation between the measured mean grey scale and echogenicity. Standard deviation within the grey scale was redundant, and there was no correlation between the other subjective characteristics and quantitatively measurable values.

Fatty Liver↗
PubMed1985

[Importance of thyroid hormone determination in the diagnosis of hyperthyroidism--significant improvement in medical assessment using decision theory results].

A "schematic" classification of the results of serum thyroid hormone measurements on the basis of mathematical decision theory proves to be superior to the physicians' conventional evaluation. That has been shown by comparison with the evaluations made by three experienced doctors. When using no control regions (but the results of serum T4, FT4 and T3 simultaneously) the physicians' rates of misrecognition (0-2% false positives, 20-27% false negatives) are only a little lower than when classifying schematically on the basis of only one thyroid hormone. The construction of a suitable control region, however, results when T3 alone is used, in only 7% false negative and 0% false positive results, while these rates remain nearly unchanged for the physicians' evaluations. The optimum application of mathematical decision theory is only possible with the knowledge of the statistical distributions of the thyroid hormone data, both for a representative collective of normals and that of patients with proven hyperthyroidism. Thus, quantitative criteria for the effectiveness of each set of thyroid hormones can be constructed and a multivariate analysis can be performed, in our example - when applying suitable control regions - even with vanishing rates of misrecognition.

Decision Theory↗
PubMed1984

On the optimum selection of diagnostic tests in computer-aided differential diagnosis.

A new method with multivariate individual selection of diagnostic tests for computer-aided differential diagnosis is presented. It has been developed on the basis of new results of our own in the field of mathematical decision theory. Its application to the differential diagnosis of four congenital heart diseases by means of ECG features proves our method to be superior to the usual multivariate statistical analysis. Establishing the individual optimum sequence of diagnostic tests for each patient our diagnostic procedure needs only two-thirds of the diagnostic tests used by the methods until now without an increase of the error rate. The error rate can be further reduced by additional introduction of the so-called reserved diagnostic statement. The managing of our procedure may be compared with the diagnostic behavior of a physician.

Child↗
PubMed1980

A computer program suitable for analysis of choice of categories in biomedical data recognition problems.

The optimum choice of categories in problems of medical data recognition is governed by the choice of categories, the selection of appropriate features, and by the choice of a loss function. Under these circumstances it is often difficult to find out the suitable classification scheme. The computer program described here serves for the design of the optimum recognition procedure. The Bayes rule is used as decision rule. A criterion for the comparison of different choice of categories is given. The program can be performed after estimation of the underlying prior probabilities and the conditional densities obtained from a training set, and before testing the decision rule with real data.

Classification↗
PubMedDate not supplied

[Retrospective analysis of results of treatment of 91 oral cavity cancers from 1982 to 1992].

PURPOSE: To analyse retrospectively the results of different treatment regimens of carcinomas of the floor of the mouth and tongue. MATERIALS AND METHODS: Between 1982 and 1992, 61 patients with carcinoma of the floor of the mouth and 30 with tongue cancer (25 stage I, nine stage II, 28 stage III, 29 stage IV) were treated in the radiotherapy department of Poitiers. Nine patients with stage I tumours were treated with 70 Gy low-dose rate brachytherapy only, without nodal dissection. Stages II and III were treated with combined surgery with neck dissection; and radiotherapy of stage II with nodal metastasis and for all stage III cases. Stage IV cases were treated either surgically if possible, or with combined chemotherapy and radiation. RESULTS: The five-year overall survival rate was 87.3% for stage I, 68.5% for stage II, 45.3% for stage III, and 0% for stage IV patients. Most relapses appeared in the first two years after treatment. Eight patients (32%) with stage I cancer developed nodal relapses, isolated in five cases. Complications of radiotherapy were acceptable. Four cases of osteonecrosis were observed after radiotherapy. All of these appeared simultaneously with a local relapse. CONCLUSION: These results are comparable with reports in the literature. The remarkable observation of our study is the high incidence of nodal recurrences after local treatment of stage I tumours. Therefore, local treatment is insufficient for early-stage tumours. The question of neck dissection for the early stage is discussed.

Adult↗
PubMedDate not supplied

[Retrospective analysis of the reproducibility of the daily set-up of the irradiation fields of cancer of the rectum using a megavoltage imaging system].

PURPOSE: To evaluate a ionization chamber on-line portal imaging system in routine clinical radiotherapy of rectum cancers. PATIENTS AND METHODS: Megavolt portal images were obtained using a fast electronic megavoltage radiotherapy imaging system in 13 cases of pelvic fields. A total of 208 portal images and 13 simulator films were used to determine the values of set-up deviations in the X-Z-directions of a fixed co-ordinate system, and of the rotation fields (R). RESULTS: Mean standard deviations of the difference between simulation and treatment images were 3.2 mm and 0.9 mm for X and Z, 3.6 mm for the rotation fault. The standard deviations were, respectively, 7.1 mm, 7.1 mm and 1.5 mm. The cumulative frequency distributions revealed that 80% and 95% of the absolute differences were less than 10 mm and 17.5 mm, respectively. CONCLUSION: These results indicate the difficulty of a reproducible daily set-up. A weekly control could be proposed in order to increase the quality of pelvic site treatment. The introduction of masks to improve the set-up is also discussed.

Humans↗
PubMedDate not supplied

[In vitro study of a paclitaxel-radiotherapy combination on a human epidermoid tumor cell line].

PURPOSE: Paclitaxel is an agent which stabilizes microtubules, and has been shown to block different cells in the G2/M phase of the cell cycle and thus to modulate their radioresponsiveness. We investigated the radiosensitizing potential of paclitaxel in human head and neck cancer cells. MATERIALS AND METHODS: ZMK-1 cells were incubated with paclitaxel for 3, 9, or 24 h before or during 24 h after irradiation. Paclitaxel concentrations of 70 nM, 7 nM, and 0.7 nM were chosen to obtain equivalent toxicity at the different incubation times: 3 h, 9 h, and 24 h, respectively. Radiation doses ranged from 0 to 8 Gy using 60Co source. Cell survival was measured by a standard clonogenic assay after a 9-day incubation. Flow cytometry was used to measure the capacity of paclitaxel to accumulate cells in the G2/M phase. RESULTS: Paclitaxel alone possessed cytotoxicity dependent on time and concentration. There was a total of 40% of cells accumulated in G2/M after 24-36 h. When combined with radiation, the 9 h preincubation resulted in a radiosensitization. The 3 h pre-incubation as well as the 24 h post-incubation resulted in an infra-additive effect. CONCLUSION: In our cells a radiosensitizing effect of paclitaxel could not be demonstrated unambiguously. The blockage of the cells in the G2/M phase is not the only mechanism to explain the potential radiosensitization of paclitaxel.

Drug Screening Assays, Antitumor↗
PubMedDate not supplied

MR imaging of urinary bladder neoplasms.

The diagnostic potential of magnetic resonance (MR) imaging at 1.5 T for assessment and staging of urinary bladder tumors was investigated in 10 patients with malignant urinary bladder tumors. All patients underwent complete pathologic staging. The appearance of the urinary bladder tumors and the ability to stage them by means of MR imaging was evaluated morphologically and compared with results obtained with pathologic examination. Magnetic resonance imaging permitted tumor localization in all patients. In nine patients the tumor stage was accurately determined by MR imaging. The smallest tumor detected by MR imaging was 1.5 cm. Both transverse and sagittal imaging planes were found to be essential for accurate assessment of tumor extension. Signal intensity data obtained from both dual and multi spin echo sequences showed that tumor display and depth of infiltration was best seen with a repetition time (TR) of 2,000 ms and an echo time (TE) of 90 ms. Accurate evaluation of perivesical tumor infiltration required a sequence with a TR 800 ms and a TE 30 ms. Data presented here further support the role of MR in staging urinary bladder neoplasms.

Aged↗
PubMedDate not supplied

Focal lesions of the spleen: preliminary results with fast MR imaging at 1.5 T.

Sixteen patients with splenic lymphoma and six with nonlymphomatous splenic lesions underwent magnetic resonance (MR) imaging, ultrasound (US), and dynamic CT. All patients were studied at 1.5 T with gradient echo sequences using a repetition time of 80 ms, echo time of 16 ms, and two pulse angles of 30 and 60 degrees. In 14 patients with lymphomatous lesions fast MR showed circumscribed areas of low signal intensity at both pulse angles. The lesion-to-spleen contrast was better on images acquired with a pulse angle of 30 degrees. For fast MR with pulse angles of 30 degrees, the mean lesion-to-spleen contrast was similar to US and contrast-enhanced CT. However, with fast MR the contrast showed a lower variability and was considerably better than with unenhanced CT. In one patient fast MR showed splenic involvement that was missed on both CT and US. The signal characteristics of lymphomatous, leukemic, and sarcoid involvement and of healed infarcts were similar and indistinguishable on fast MR images. Recent splenic infarctions (three cases) were, however, distinctly different, characterized by regions of high signal intensity at both pulse angles. The results of this preliminary study suggest that fast MR imaging is a promising diagnostic tool for the assessment of splenic disorders.

Diagnosis, Differential↗