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K Wernecke

Publications and source records attributed to K Wernecke.

At least 19 recordsLinked to original sources
PubMed1992

Comparison between high-field-strength MR imaging and CT for screening of hepatic metastases: a receiver operating characteristic analysis.

The diagnostic performance of high-field-strength magnetic resonance (MR) imaging (1.5 T) for detection of liver metastases was compared with that of computed tomography (CT). All patients (n = 52) underwent preoperative screening for metastases by means of MR imaging with T1-weighted, proton-density-weighted, and T2-weighted pulse sequences and CT scanning with unenhanced, incremental dynamic bolus-enhanced, and delayed contrast medium-enhanced techniques. Diagnostic performance was evaluated by means of receiver operating characteristic analysis in which 800 images (400 with and 400 without lesions) and five readers (4,000 observations) were used; images were obtained from patients (n = 39) in whom the same anatomic levels were available for all MR imaging and CT studies. Direct comparison between the best MR imaging technique (T2-weighted spin-echo imaging [repetition time, 2,000 msec; echo time, 70 msec]) and the best CT technique (incremental dynamic bolus CT) showed a strong trend of superiority of T2-weighted MR imaging over incremental dynamic bolus CT. No highly statistically significant difference (P greater than or equal to .01), however, was found between these two techniques.

Esophageal Neoplasms↗
PubMed1992

Differentiation of benign from malignant superficial lymphadenopathy: the role of high-resolution US.

Ultrasonography has proved a valuable tool for the detection of enlarged lymph nodes; however, differentiation between benign and malignant nodal disease remains a problem. High-frequency probes with improved spatial and contrast resolution display superficial nodes to advantage and also show the internal structure of the nodes. Ninety-four superficial nodes in patients with suspected nodal disease were examined by using 7.5-MHz probes to evaluate longitudinal-transverse diameter ratio (L/T), the central hilus, cortical widening, and size. Histologic diagnosis was obtained after sonographic examination in 73 nodes (five reactive nodes, 35 primary nodal malignancies, and 33 nodal metastases). The remaining 21 nodes regressed after either antibiotic or no therapy. Marked differences were observed among the proportions of benign and malignant nodes in terms of L/T, hilus, and cortex; the latter two structures, however, must be interpreted together. Eccentric cortical widening was seen in only malignant nodes. The distribution of nodal size was not significantly (P greater than .1) different for benign and malignant nodes. No differences were observed between primary and secondary nodal malignancies. The sonographic criteria evaluated in this study assist in the differentiation of benign from malignant superficial lymph nodes.

Adult↗
PubMed1992

The distinction between benign and malignant liver tumors on sonography: value of a hypoechoic halo.

OBJECTIVE: The purpose of this study was to determine the diagnostic value of the sonographic halo sign (defined as any hypoechoic rim in the periphery of a lesion) in distinguishing between benign and malignant isoechoic and hyperechoic liver lesions on sonography. MATERIALS AND METHODS: Sonograms of the liver in 50 patients with proved benign liver tumors and in 50 patients with proved malignant liver tumors (seven primary liver neoplasms, 43 metastases) selected during a 13-month period were retrospectively analyzed by four radiologists who had no knowledge of the patients' clinical findings or the final diagnoses. Only a single sonogram was studied in each case. The presence or absence of a hypoechoic halo on the sonogram was the only criterion for distinguishing malignant from benign hepatic lesions. RESULTS: For 95 of 100 hepatic lesions, the four radiologists were almost (three vs one) or completely (four vs zero) in agreement about the presence or absence of a hypoechoic halo. In the five cases where there were conflicting decisions (two vs two), a final decision (four vs zero) was achieved by reviewing the entire series of sonographic images. A halo could be detected in 44 malignant tumors (88%) and in only seven benign tumors (14%) (sensitivity, 88%; specificity, 86%; positive and negative predictive values, 86% and 88%, respectively). The sonographic halo sign was particularly helpful in distinguishing hemangiomas (n = 29) from metastases (n = 43) (positive and negative predictive values, 95% and 87%, respectively). CONCLUSION: The results of this study suggest that the halo sign on sonograms is useful to distinguish benign from malignant isoechoic or hyperechoic tumors.

Adult↗
PubMed1992

Pathologic explanation for hypoechoic halo seen on sonograms of malignant liver tumors: an in vitro correlative study.

OBJECTIVE: The purpose of this study was to evaluate the morphologic substrate of the hypoechoic halo seen on sonograms of malignant liver tumors. MATERIALS AND METHODS: We used sonograms and pathologic examinations to evaluate 17 cadaveric livers with macroscopic tumors (three primary liver tumors, 14 metastases). During sonography (3.5 and 5.0 MHz), a representative section plane was marked, and the same section was examined histologically. Emphasis was placed on the architecture of the tumor and the morphology of the periphery of the tumor that could account for the hypoechoic halo seen on sonograms. RESULTS: In 13 of 17 hepatic tumors, a hypoechoic halo was detected on sonograms. Histopathologic examination showed an intratumoral rim consisting of proliferating tumor cells in 12 cases and an extratumoral rim of compressed liver parenchyma in all 13 cases. A detailed comparison of sonographic and histopathologic findings showed that the hypoechoic halo corresponded to a greater concentration of tumor cells and areas of less marked fibrosis and necrosis in the periphery of the tumors. This occurred in 11 cases. In one case, histologic studies showed that the hypoechoic rim was caused by compressed liver parenchyma. In another case, the hypoechoic halo was caused by intratumoral (cellular peripheral zone of tumor) and extratumoral (compressed liver parenchyma) components. All four tumors without a halo at sonography were uniform histologically. CONCLUSION: The sonographic halo seen on sonograms of malignant liver tumors seems to be caused predominantly by a zone of proliferating tumor in the periphery of the lesion.

Adenocarcinoma↗
PubMed1991

[The potentials and limits of percutaneous needle biopsy in the histological classification of malignant tumors].

180 sonographically guided percutaneous biopsies in a variety of anatomic regions (abdomen, 110; thorax, 33; neck, 28; breast, 4; extremity, 5) were retrospectively reviewed to evaluate the percentage of correct histologic diagnoses of malignant tumours. A positive diagnosis of malignancy was established in 101 (96%) of 107 malignant tumours. A correct histologic classification was achieved in 79 (73%) of 108 malignant tumours by means of cytologic and histologic examination of the tissue acquired. Correct histologic classification of malignant tumours depends on several factors including a) needle diameter, b) location of the tumour, c) clinical constellation and, most important d) the complexion of the tumour histology. The percentage of correct histological diagnoses varied between carcinomas (79%), Hodgkin lymphomas (100%), non-Hodgkin lymphomas (45%), sarcomas (50%) and carcinoid tumours (0%). Histological classification of malignant tumours by means of percutaneous biopsy can be improved by multiple biopsies of different portions of the tumour and by using larger cutting needles.

Adolescent↗
PubMed1991

Thymic involvement in Hodgkin disease: CT and sonographic findings.

To evaluate the morphologic characteristics and frequency of thymic enlargement in Hodgkin disease, the initial and follow-up computed tomographic (CT) scans of 43 patients with newly diagnosed Hodgkin lymphoma were retrospectively analyzed. Sonograms of the thymic region in 21 patients were also available and were compared with the CT scans. Initial CT scans showed thymic enlargement in 17 of the 43 patients, no evidence of thymic enlargement in 15 patients, and equivocal findings in 11 patients. Analysis of follow-up CT scans indicated that seven of the 11 patients with initially equivocal findings had had thymic enlargement. In all seven patients, the anterior mediastinal tumor shrank with therapy and adopted a typical tongue-shaped thymic configuration. In nine of the 24 patients with thymic enlargement, the thymus remained enlarged after therapy and full clinical remission. The comparison of sonograms and CT scans showed that sonography could not help differentiate the normal-size thymus from surrounding fatty tissue. All thymic glands that were considered diseased because of enlargement at CT were sonographically visible due to an abnormal, hypoechoic structure. The results of the study show that thymic enlargement presumed to be due to involvement by Hodgkin disease seems to occur more frequently than previously reported.

Adolescent↗
PubMed1991

Value of sonography in monitoring the therapeutic response of mediastinal lymphoma: comparison with chest radiography and CT.

The aim of this retrospective study was to assess the diagnostic value of mediastinal sonography, compared with that of chest radiographs and CT, in the follow-up of patients with mediastinal lymphomas and in the prediction of clinical outcome. The sonograms, chest radiographs, and CT scans of 40 consecutive patients with Hodgkin (n = 29) and non-Hodgkin (n = 11) lymphoma obtained before and after completion of therapy were analyzed blindly and independently by three radiologists and compared with clinical outcome. Nine patients were treated with radiotherapy, 12 with chemotherapy, and 19 with combined therapy. Therapeutic response was assessed from all available clinical and biochemical findings as well as from the combined results of all imaging studies performed on further follow-up. The sonograms showed obvious changes in the size and echogenicity of the mediastinal lymphomas that corresponded closely with the response to therapy. Sonography showed complete regression of the lymphomas in 30 patients who had complete remission. In five patients with incomplete remission, sonographic diagnoses were correct. All lymph nodes, irrespective of size, detected with sonography after a phase of complete remission indicated recurrence (five patients). Sonographic findings corresponded with those of CT in 25 (81%) of 31 cases. Clinical outcome suggested that the sonographic findings were more reliable in the five cases in which CT and sonographic findings conflicted. Chest radiographs were inadequate for monitoring the response of mediastinal lymphomas to therapy; in 17 (43%) of 40 cases, a false impression was obtained of the extent and therapeutic response of mediastinal lymphomas. The results of this study indicate that sonography is clearly superior to chest radiographs and comparable to CT for monitoring patients with mediastinal lymphomas.

Adolescent↗
PubMed1991

Detection of hepatic masses in patients with carcinoma: comparative sensitivities of sonography, CT, and MR imaging.

To evaluate the sensitivity of sonography, CT, and MR imaging in the detection of hepatic masses in carcinoma patients, we conducted a prospective study of 75 consecutive patients with gastrointestinal tumors who were admitted for surgical resection of the primary tumor. Sonography was performed with convex transducers of 3.5 and 5.0 MHz. Three noninvasive CT techniques were used: unenhanced CT scans, the incremental bolus dynamic scanning technique, and delayed scanning 4-6 hr after bolus injection of 60 g of iodine. MR images (1.5 T) were acquired as presaturated T1- and T2-weighted spin-echo sequences and as breath-holding fast low-angle shot (FLASH) 60 degrees and FLASH 15 degrees sequences. As it is difficult to distinguish benign from malignant masses solely on the basis of morphologic criteria, the techniques for each imaging method were designed to detect and not to characterize hepatic lesions. Each examination was interpreted blindly, and the results were compared with surgical findings, intraoperative sonography, and biopsy of the liver as the gold standard. All focal hepatic masses verified at surgery, malignant or benign, were included in the analysis. Sixty-five (68%) of 95 focal hepatic masses were detected by CT, 60 lesions (63%) by MR, and 50 lesions (53%) by sonography. Although lesions 1-2 cm were shown almost equally well by CT and MR (74% and 77%, respectively), the detection rate of smaller lesions (less than 1.0 cm) decreased more drastically with MR (31%) than with CT (49%). Sonography had a sensitivity of only 20% with the smaller lesions. All imaging techniques had a sensitivity of 100% for focal hepatic masses larger than 2.0 cm. Our results show that CT has a higher overall sensitivity (68%) than MR and sonography for the detection of focal hepatic masses. When the results of the three procedures are combined, the overall sensitivity is 77%. This is unsatisfactorily low, as CT and MR have a size threshold of about 1.0 cm and are relatively unreliable for the detection of smaller lesions.

Adenocarcinoma↗
PubMed1991

[Parathyroid sonography in long-term dialysis].

In a prospective study the prevalence of sonographically enlarged parathyroid glands in patients on maintenance hemodialysis was investigated and correlated with clinical and laboratory findings of secondary hyperparathyroidism. We examined 97 unselected patients with a 5 MHz probe. In 34% (33/97) a total of 69 parathyroid glands were detected with a statistically significant correlation between the period of dialysis and the incidence of parathyroid enlargement; 47.8% of the glands were hypoechoic, 34.8% moderately echogenic and 17.3% gave echoes similar to the normal thyroid parenchyma. A correlation was found between the finding of enlarged parathyroid glands and blood levels of calcium and alkaline phosphatase. Parathyroid enlargement was found sonographically before, or in the absence of clinical and laboratory findings of secondary hyperparathyroidism. Sonography is therefore a useful technique for early diagnosis of hyperparathyroidism in patients on maintenance dialysis.

Adult↗
PubMed1990

Mediastinal tumors: sensitivity of detection with sonography compared with CT and radiography.

The purpose of this prospective study was to evaluate the sensitivity of mediastinal sonography compared with computed tomography (CT) and chest radiography in the detection of mediastinal tumors. The sonograms, CT scans, and chest radiographs of 182 patients were interpreted blindly by three observers, and the results were compared. The proportion of diagnostic sonographic examinations varied for the different mediastinal compartments from 85% (subcarinal region) to 96% (supraaortic region). The sensitivities of sonography and chest radiography, respectively, for each compartment, with CT as the reference method, were as follows: supraaortic region, 98% and 67%; paratracheal region, 89% and 69%; aorticopulmonary window, 81% and 62%; prevascular region, 92% and 46%; subcarinal region, 69% and 31%; pericardial region, 100% and 67%; posterior mediastinum, 6% and 6%; and paravertebral region, 11% and 44%. These results show that sonography is superior to chest radiography in the diagnosis of mediastinal tumors. In certain mediastinal regions (supraaortic, pericardial, prevascular, and paratracheal), sonography is so sensitive that CT and magnetic resonance examinations may be obviated in patients with equivocal radiographic findings.

Adolescent↗
PubMed1990

[Diagnostic imaging of mediastinal tumors. Sensitivity and specificity of sonography in comparison with computed tomography and conventional x-ray diagnosis].

The purpose of this prospective study was to evaluate the sensitivity of mediastinal sonography compared to CT and chest radiography in the detection of mediastinal tumors. The sonograms, computed tomograms and chest radiographs of 182 patients were interpreted blindly by three observers and the results of all three procedures were compared. The proportion of diagnostic sonographic examinations varied in the different mediastinal compartments from 85% (subcarinal region) to 96% (supra-aortic region). The sensitivities of sonography and chest radiography (using CT as the gold standard) in the imaging of mediastinal tumors for each compartment were as follows: supra-aortic region: 98% and 67%; paratracheal region: 89% and 69%; aorticopulmonary window: 81% and 62%; prevascular region: 92% and 46%; subcarinal region: 69% and 31%; pericardial region: 100% and 67%; posterior mediastinum: 6% and 6%; paravertebral region: 11% and 44%. These results show that sonography is superior to chest radiography for the diagnosis of mediastinal tumors. In certain mediastinal regions (supra-aortic, pericardial, prevascular and paratracheal region), sonography is so sensitive that CT and MR examinations may be avoided in cases with equivocal radiographic findings.

Adolescent↗
PubMed1989

[Sonographic diagnosis of pneumothorax].

The sonographic appearances of the pleura were studied in 20 normals and in eight patients with radiologically confirmed pneumothoraces. In all 20 normals it was possible to demonstrate the respiratory excursion of the visceral pleura. Moreover, the margin between pleura and aerated lung parenchyma was marked by artifacts resembling a comet's tail. In all eight patients with pneumothoraces pleural air could be inferred by the absence of pleural movement and of the comet-tail artifacts. In emergency situations, where it is not possible to obtain radiographs, or to obtain them with sufficient speed, sonography may make a crucial contribution to the diagnosis of a pneumothorax.

Adolescent↗
PubMed1989

[The examination technic and indications for mediastinal sonography].

The purpose of this report is to describe the technique of suprasternal and parasternal mediastinal sonography. Via the suprasternal approach, the supraaortic region, the paratracheal region and the aorticopulmonary window can be evaluated. The parasternal approach in right and left decubitus position is suitable for imaging the anterior mediastinum, pericardial and subcarinal spaces. The proportion of technically inadequate examinations of the different mediastinal compartments varies between 4 and 15%. The main indications for mediastinal sonography are described from our experience in the last 4 years.

Adult↗
PubMed1989

Mediastinal tumors: biopsy under US guidance.

Percutaneous biopsies of mediastinal tumors were successfully performed under sonographic guidance in 14 of 21 patients. In 10 of 11 malignant lesions, malignancy was determined by means of cytologic and histologic examination of the specimens obtained. A histologic diagnosis was reached in seven patients with malignant mediastinal tumors, including all four cases of Hodgkin lymphoma. Mediastinal biopsy under sonographic guidance is a technically simple, rapid, and accurate procedure, but its application is limited to tumors of the anterior mediastinum.

Biopsy, Needle↗
PubMed1989

[Sonographic diagnosis of liver and pancreatic tumors].

From an overall point of view sonographic diagnostics of tumours of the liver is characterised by a high degree of sensitivity. Although an approximate differentiation between benign and malignant tumours is possible, it is not sufficiently reliable. Compared with the often monotonous CT imaging of liver tumours, the extremely "colourful" sonographic image (which seems to be full of "variety of species") of lesions of the liver supplies decisive pointers, so that the range of tumours to be considered in differential diagnosis becomes more limited. Such preselection is important especially for the choice of further measures to confirm the diagnosis. Sonographic differentiation between primary and secondary liver tumours is uncertain, and hence histological verification is mandatory. In what way sonography can help to determine whether a tumour is operable or not, has not yet been studied and is therefore by no means clear. Sonography is highly sensitive in the detection of tumours of the pancreas, especially with minor lesions of less than 2 cm diameter. The sonographic image of the adenocarcinoma is non-specific, so that it must be considered imperative to clarify by histological examination even extensive findings that appear totally inoperable, so that a distinction can be made against tumours of the pancreas which have a better prognosis. Sonographic assessment of whether or not a tumour can be resected can only be effected in a negative sense if there are unequivocal sonographic criteria proving that the tumour is inoperable.

Humans↗
PubMed1988

Parasternal mediastinal sonography: sensitivity in the detection of anterior mediastinal and subcarinal tumors.

Twenty-seven patients with anterior mediastinal and subcarinal mediastinal tumors confirmed by CT and 30 control subjects were prospectively investigated by sonography performed via a parasternal approach in both decubitus positions. The sonograms and CT scans were interpreted blindly by two investigators and the results of the two procedures were compared. In the group of 30 controls, sonography via the right parasternal approach showed the anterior mediastinum in 29 (97%) and the subcarinal space in 27 (90%). Fifteen (94%) of 16 anterior mediastinal tumors and 16 (94%) of 17 subcarinal tumors were identified sonographically. These results show that parasternal sonography is a sensitive technique for the detection of tumors in the anterior mediastinal and subcarinal mediastinal spaces.

Adult↗