Biomedical subjects

D Tscholakoff

Publications and source records attributed to D Tscholakoff.

At least 73 records · Page 4Linked to original sources

PubMed1987

[Analysis of errors in imaging diagnosis of varicocele. Duplex sonography, plate thermography and phlebography].

Comparative investigations were done by duplex sonography, thermography and phlebography in 142 patients with 158 varicoceles. Verification of clinical varicoceles (130/158) was performed by duplex sonography in all cases and by thermography in 93%. Measurement errors were due to dorsally located varicoceles near the radix of the penis (3/130) and by small, two-sided varicoceles (6/130). Small subclinical varicoceles (28/158) were detected by real-time sonography in 89%, by Doppler sonography in 64%, and by thermography in 53%. In three patients with normal real-time sonography, subclinical varicoceles were found by Doppler sonography alone. The combination of both sonographic methods is highly sensitive for the detection of subclinical varicoceles and should be done in all cases without therapeutic results.

Humans↗

PubMed1987

Evaluation of pleural and pericardial effusions by magnetic resonance imaging.

MR examinations of 36 patients with pleural and/or pericardial effusions were retrospectively evaluated. The purpose of this study was to determine of MR imaging is capable of differentiating between pleural and pericardial effusions of different compositions using standard electrocardiogram (ECG)-gated and non-gated spin echo pulse sequences. Additional data was obtained from experimental pleural effusions in 10 dogs. The results of this study indicate that old hemorrhages into the pleural or pericardial space can be differentiated from other pleural or pericardial effusions. However, further differentiation between transudates, exudates and sanguinous effusions is not possible on MR images acquired with standard spin echo pulse sequences. Respiratory and cardiac motion are responsible for signal loss, particularly on first echo images. This was documented in experiments in dogs with induced effusions of known composition; "negative" T2 values consistent with fluid motion during imaging sequences were observed in 80% of cases. However, postmortem studies of the dogs with experimental effusions showed differences between effusions with low protein concentrations and higher protein concentrations. We conclude from our study that characterization of pleural and pericardial effusions on standard ECG-gated and non-gated MR examinations is limited to the positive identification of hemorrhage. Motion of the fluid due to cardiac and respiratory activity causes artifactual and unpredictable changes in intensity values negating the more subtle differences in intensity associated with increasing protein content.

Animals↗

PubMed1986

[Hypertrophic pyloric stenosis--an indication for sonography].

The pyloric region of 58 infants who presented with vomiting was examined by real-time ultrasound. Transverse diameter of the pylorus and single wall thickness were measured. In 18 patients sonographic diagnosis of hypertrophic pyloric stenosis (HPS) was made and subsequently confirmed by surgery. The mean (+/- one standard deviation) of the transverse diameter and of the pyloric wall thickness in patients with HPS was 15 (+/- 1) mm. and 5.5 (+/- 0.7) mm., respectively. Forty infants matched for age and sex distribution without gastrointestinal symptoms served as controls. The measurements for the transverse diameter were 9.6 (+/- 1.8) mm. and for the wall thickness 1.9 (+/- 0.5) mm. Diameter values of patients with HPS were significantly (p less than 0.001) higher than those of the control group and those of the remaining 40 patients without HPS. Real-time sonography proved a reliable tool in the diagnosis of HPS.

Age Factors↗

PubMed1986

Uterine leiomyomas: correlation of MR, histopathologic findings, and symptoms.

Magnetic resonance (MR) imaging, symptoms, and pathologic findings were correlated in 59 uterine leiomyomas from 23 patients. The tumors varied from less than 1 cm to 18 cm in diameter. Fifty-seven leiomyomas were identified in the corpus uterus, one was located within the broad ligament, and another was detected in the cervix. Among the corpus lesions, 9 were correctly identified on MR images as subserosal and 37 as intramural. Of 11 tumors assigned at surgery to the submucosal group, 10 had been accurately defined with MR. On MR, myomas associated with hypermenorrhea produced an anatomic disruption of the "junctional zone" (the low-intensity band seen at the myometrium-endometrium junction on T2 contrast images). Long TR (2 sec) and TE (56 msec) parameters (T2 contrast images) yielded the best contrast resolution between leiomyoma and surrounding myometrium. Correlation of MR with histologic features demonstrated 2 groups of lesions. Leiomyomas free of degenerative changes emitted homogeneous signals of low intensity. Contrast between tumor and myometrium was -16% on the T1 contrast image and increased to -44 +/- 16% on the T2 contrast image. Leiomyomas with hyaline, myxomatous, or fatty degeneration demonstrated various degrees of inhomogeneity, best seen on images obtained with long TR and TE. It is concluded that MR is an accurate modality for imaging uterine leiomyomas, since it clearly demonstrates tumor number, size, location, and the presence and extent of degeneration.

Adipose Tissue↗

PubMed1986

Mediastinal masses: MR imaging.

Seventy-five patients with mediastinal masses were imaged with magnetic resonance (MR). Results were analyzed with regard to the ability of MR to demonstrate the masses, their morphology, and their encroachment or displacement of blood vessels and airways. T1 values were determined in 53 patients and T2 values in 59. Hydrogen density and percentage of contrast relative to muscle and fat were also obtained in 53 and 59 patients, respectively. MR images were compared with computed tomography (CT) scans, which were available in 45 patients. MR depicted all masses and demonstrated compromise of vessels and cardiac chambers owing to the inherent contrast between the masses and cardiovascular structures. Bronchogenic carcinoma had very long relaxation values for T1 and T2, while chronic inflammatory processes had intermediate values for T1 and T2, thus appearing less intense than bronchogenic carcinoma on T2-weighted images. Other neoplasms demonstrated T1 and T2 values between these two disease groups. Masses appeared less homogeneous on MR images than on CT scans, and vascular compromise was better assessed with MR. Thus, MR imaging is a completely noninvasive technique for the evaluation of mediastinal masses. While the anatomic information is comparable to that produced by CT, MR provides some insight into the composition of the mass.

Adolescent↗

PubMed1986

Adnexal structures: MR imaging.

Magnetic resonance (MR) images of the pelvis in 63 women (40 healthy and 23 with various adnexal diseases) were assessed retrospectively. When imaged with contiguous sections without gaps, adnexa were demonstrated bilaterally in 13 of the 15 healthy women of reproductive age, but in only seven of the 15 healthy postmenopausal women. Normal adnexa demonstrated low to medium signal intensity on images obtained with short repetition time (TR) (0.5 sec) and echo delay time (TE) (28 or 30 msec). Their signal intensity approached that of fat on images with a long TR (2.0 sec) and TE (56 or 60 msec). The adnexal origin of the pelvic masses was correctly identified in every case. Lesions containing fluid with little or no protein, fat, or blood content (simple fluid) had characteristically long T1 and T2 relaxation times and low signal intensity on images obtained with a short TR (0.5 sec) and TE (28 or 30 msec); they could be readily differentiated from all the other types of lesions.

Adipose Tissue↗

PubMed1986

Lymph nodes of the neck: evaluation with US.

Ultrasound (US) proved highly effective for detection, localization, and delineation of enlarged lymph nodes of the neck. Infiltration of adjacent structures, specifically the common, internal, and external carotid arteries, and the neck muscles was reliably demonstrated. Benign and malignant lymph node enlargement could not be differentiated. US examinations changed the operative course of 56% of patients studied. In 41%, a more radical operative procedure was performed than was previously planned; in 14%, US demonstrated inoperability. Small-parts US is a very useful adjunct to current imaging techniques of cervical lymph node disease.

Humans↗

PubMed1986

Differentiation of reversible and irreversible myocardial injury by MR imaging with and without gadolinium-DTPA.

The current study evaluated the capability of magnetic resonance (MR) imaging to distinguish myocardium subjected to reversible and irreversible ischemic injury. Nine dogs underwent left anterior descending coronary arterial occlusion for 15 minutes (reversible injury) and nine for 1 hour (irreversible injury), followed by reperfusion for 24 hours in both groups. Six dogs from each group received 0.5 mmol/kg of gadolinium-DTPA intravenously; the remaining dogs received no contrast media. In the dogs with irreversible injury but no contrast media, there were prolonged T1 and T2 of the infarcted myocardium and adequate visualization of the infarct. The percentage of contrast between normal and infarcted myocardium was greatest on T2-weighted images. In the group with irreversible injury and contrast media, Gd-DTPA produced significant T1 shortening of injured myocardium, with resultant high signal intensity of the infarct, and significantly enhanced contrast compared with the group that did not receive Gd-DTPA. In the dogs with reversible injury, there were no regional differences in intensity or relaxation times. MR has the capability to distinguish myocardium with irreversible injury from that with reversible injury. The difference of T1 between normal and reperfused infarcted myocardium is increased by Gd-DTPA; thus, contrast between these two is enhanced on MR images.

Animals↗

PubMed1986

Early-phase myocardial infarction: evaluation by MR imaging.

In vivo gated magnetic resonance (MR) imaging was performed in 12 dogs immediately after occlusion of the left anterior descending coronary artery and serially up to 5 hours and again between 4 and 14 days. This was done to evaluate the appearance of acute myocardial infarcts and to determine how soon after coronary artery occlusion MR imaging can demonstrate the site of acute myocardial ischemia. In nine dogs with postmortem evidence of myocardial infarction, regional increase of signal intensity of the myocardium was present by 3 hours after coronary artery occlusion and conformed to the site of myocardial infarct found at autopsy. The signal intensity on T2-weighted images of the infarcted myocardium was significantly greater than that of normal myocardium at 3, 4, and 5 hours after occlusion. The T2 (spin-spin) relaxation time was significantly prolonged in the region of myocardial infarct at 3, 4, and 5 hours postocclusion compared with normal myocardium. Myocardial wall thinning and increased intracavitary flow signal were found in six dogs with comparable pre- and postocclusion images in late systole.

Animals↗

PubMed1986

Occlusive and reperfused myocardial infarcts: effect of Gd-DTPA on ECG-gated MR imaging.

In vivo magnetic resonance (MR) imaging was performed to determine the effect of gadolinium-DTPA on MR intensity and relaxation times of occlusive and reperfused acute myocardial infarcts. In 18 dogs the left anterior descending (LAD) coronary artery was ligated. Five hours after LAD artery occlusion, six dogs in group 1 received intravenous Gd-DTPA, 0.5 mmol/kg, and 6 dogs in group 2 received 0.1 mmol/kg. The myocardia of the remaining six dogs (group 3) were reperfused after 1 hour of coronary artery occlusion; these dogs received 0.1 mmol/kg Gd-DTPA intravenously 5 hours later. MR imaging was performed before (control) and 5 minutes after Gd-DTPA administration. Intravenous administration of 0.1 mmol/kg Gd-DTPA significantly improved contrast between infarcted and normal myocardium on T1-weighted spin echo images in group 3. In all groups, T2-weighted precontrast images provided contrast between infarcted and normal myocardium equivalent or better than that provided by T1-weighted postcontrast images. Thus, Gd-DTPA did not improve contrast between ischemically injured and normal myocardium in the early hours after coronary artery occlusion.

Animals↗

PubMed1986

Magnetic resonance imaging of cardiac transplants: the evaluation of rejection of cardiac allografts with and without immunosuppression.

The purpose of this study was to evaluate the potential of magnetic resonance imaging (MRI) in vivo for the characterization of tissue changes associated with acute myocardial rejection after cardiac transplantation. Of 15 dogs that underwent heterotopic cardiac transplantation, six served as untreated controls, and nine received immunosuppressive therapy (25 mg/kg/day cyclosporine, 1 mg/kg/day prednisone). Serial electrocardiographically gated MRI (spin-echo technique) and histologic examinations of allograft biopsy samples were performed for each dog at 2 to 3, 7 to 10, 14 to 17, and 26 to 29 days after transplantation and immediately after animals were killed. Untreated allografts showed a significant increase (p less than .01) in T2 (spin-spin) relaxation time (T2 = 66 +/- 8 msec) and intensity values compared with values in the native hearts (T2 = 44 +/- 6 msec) as early as 1 week after transplantation. The significant difference in T2 values could be observed in vivo as well as on postmortem examination and corresponded to histologic progression of the rejection process. There was no significant difference in T1, T2, or intensity values in cyclosporine-treated allografts and native hearts except in two dogs in which T2 relaxation times and signal intensity in the transplanted hearts increased simultaneously with histologic evidence of rejection, indicating failure of immunosuppressive therapy. There was a significant correlation between histologic grading of severity of rejection and T2 relaxation times of the cardiac transplants (r = .72). Likewise, there was a significant linear relationship between T2 values in vivo and percent water content when the differences between native hearts and allografts were compared (r = .92, p less than .001).(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗

PubMed1986

MRI of reperfused myocardial infarct in dogs.

The current study evaluated the capability of magnetic resonance imaging (MRI) to detect acutely injured myocardium in the first 5 hr after a 1-hr period of occlusion followed by reperfusion of the coronary artery and to determine if magnetic relaxation times could be used to differentiate injured from normal myocardium. Fourteen dogs underwent left anterior descending coronary arterial occlusion for 1 hr, followed by reperfusion. Electrocardiographic gated MRI was performed before and during coronary artery occlusion and immediately after reperfusion, and serially up to 5 hr postreperfusion. In all dogs with postmortem evidence of myocardial infarction (n = 7), regional increase of signal intensity was observed in the anterior wall of the left ventricle as early as 30 min after reestablishing blood flow to the jeopardized myocardium. The area of increased signal intensity in the myocardium conformed to the site of myocardial infarction found at autopsy. The signal intensities of the jeopardized myocardium were significantly (p less than 0.01) greater than those of normal myocardium at 30 to 300 min postreperfusion. The T2 (spin-spin) relaxation time was significantly (p less than 0.05-p less than 0.01) prolonged in the region of the reperfused myocardial infarct at 30 min (59.6 +/- 13.1 msec) and remained prolonged up to 300 min (62.6 +/- 12 msec) postreperfusion compared with the T2 of normal myocardium (40.6 +/- 5.2 msec). Of the remaining seven dogs, four developed fatal arrhythmias during the reperfusion procedure and three dogs had no evidence of myocardial infarction at pathologic examination. Signal intensities and T2 relaxation times in these three dogs did not change during the experiment. Thus, acutely infarcted and reperfused myocardium can be detected by in vivo gated MRI, using the spin-echo technique, as early as 30 min after reperfusion. The jeopardized myocardium is characterized by a prolonged T2 relaxation time and, therefore, best visualized on T2-weighted images.

Animals↗

PubMed1986

MRI of the normal pericardium.

The visibility and thickness of the pericardium, as depicted by MRI, and the changes of these parameters over the cardiac cycle were determined in 18 normal subjects. Gated, cycled, multisection images were obtained in the transaxial orientation. Using a score-point system for quantification, there was better visualization of the low-intensity pericardial line during systole as compared with diastole (p less than 0.005). Pericardial thickness was 1.2 +/- 0.5 mm in diastole and 1.7 +/- 0.5 mm in systole (p less than 0.001) as measured in a midventricular section in front of the right ventricle; both values exceeded the thickness of 0.4 to 1.0 mm reported for anatomic measurements of pericardial thickness. The layer of normal pericardial fluid present in the pericardial space should also have low intensity, and it likely contributes to the overall pericardial thickness as visualized by MRI. Since MRI is sensitive to the small amount of normal pericardial fluid and depicts its anatomic distribution, it should be valuable in detection and quantification of even small pericardial effusions.

Adult↗

PubMed1986

MRI of the abnormal pericardium.

To evaluate the use of MRI in the diagnosis of pericardial disease, 63 patients with pericardial abnormalities or clinically suspected pericardial disease were studied retrospectively. Twenty-three patients had pericardial effusion, 19 patients had pericardial thickening, and 11 patients were referred for evaluation of masses with possible pericardial involvement. The other 10 patients were referred for differentiation of constrictive pericarditis from restrictive cardiomyopathy and eventually were found to have pericardial hematoma or normal pericardium as assessed by MRI. The calculated size of pericardial effusion by MRI showed a good correlation with semiquantitative echocardiographic estimations. MRI could demonstrate fibrinous adhesions in patients with uremic pericarditis. It was also of great value in the differential diagnosis of constrictive pericarditis vs restrictive cardiomyopathy. Pericardial thickness of more than 4 mm was found in patients with constrictive pericarditis. Normal pericardial thickness was demonstrated by MRI in the three patients with restrictive cardiomyopathy. MRI diagnosed hemopericardium correctly as the cause of constrictive symptoms in two patients. Pericardial thickening in patients after cardiac surgery was commonly found by MRI and usually was not associated with clinical signs of constrictive pericarditis. MRI proved to be useful in the diagnosis of pericardial cysts and in the evaluation of paracardiac masses with possible pericardial involvement. MRI is an important technique in the evaluation of the pericardium. It can provide important additional information when diagnosis cannot be made adequately by other noninvasive imaging techniques.

Adolescent↗

PubMed1986

[Magnetic resonance tomography (MRT) in cardiovascular and lung diagnosis].

Magnetic resonance imaging (MRI) is a completely noninvasive technique for the evaluation of the cardiovascular system. With a multi-section-technique and the spin echo pulse sequence the entire heart can be examined within 10 minutes. All cardiac MR studies were performed with electrocardiographic (ECG) gating to obtain adequate resolution of the cardiac structures. With this technique patients with congenital and acquired heart diseases, with thoracic aortic aneurysms, with mediastinal and pulmonary mass lesions, with central pulmonary embolism and with pulmonary arterial hypertension were studied. MRI offers an enormous potential for cardiovascular diagnosis, even beyond the demonstration of pathoanatomy, because of the capability for direct tissue characterization and blood flow measurements.

Aortic Diseases↗

PubMed1986

[Computerized tomography (CT) and nuclear magnetic resonance tomography (MRT) in the diagnosis of liver metastasis].

Sonography and computer-tomography (CT) are the "gold-standard" in the imaging of liver-metastasis larger than 1 to 2 cm in diameter (overall-accuracy: greater than 90%). The magnetic resonance tomography (MRT) also allows the imaging of liver-metastasis due to the different relaxation-times of normal liver-tissue and metastasis. In agreement with other authors MRT shows an almost equal accuracy in the diagnosis of liver-metastasis as CT (16 patients, average age 58 years). The significantly reduced detail-resolution of MRT in comparison with CT is overcome by the gain in contrast-resolution. The smaller imaging extent in MRT is disadvantageous in the evidence of pleural effusions, bone-metastasis or lymph-node enlargements. A pathognomic differential-diagnosis of liver-metastasis by MRT is impossible. In the near future MRT of liver-metastasis can be improved by "flash"-images and may replace CT. On the other hand screening for liver-metastasis with sonography is unchallenged by MRT.

Adolescent↗

PubMed1985

Magnetic resonance imaging of the heart.

Magnetic resonance imaging (MRI) is a completely noninvasive technique for the evaluation of the cardiovascular system. With a multi-section technique and the spin echo pulse sequence the entire heart can be examined within six to ten minutes. All our cardiac MR studies were performed with electrocardiographic (ECG) gating, to obtain adequate resolution of the cardiac structures. With this technique, patients and animals with a variety of cardiac abnormalities were studied. The examined pathologic conditions included acute and chronic myocardial infarctions and their complications, hypertrophic and congestive cardiomyopathies, congenital heart diseases and pericardial diseases. MRI offers an enormous potential for cardiovascular diagnosis, even beyond the demonstration of pathoanatomy, because of the capability for direct tissue characterization and blood flow measurements.

Animals↗

PubMed1985

[Bedside chest x-rays and extravascular lung water determination in intensive care patients].

Radiological staging of pulmonary oedema was compared with the determination of extra-vascular lung water by means of a double indicator dilution technique. One hundred and forty-six ward chest radiographs were evaluated and compared with the results of simultaneous measurements of lung water. Seventy-seven cases could be evaluated statistically. Chest x-rays regarded as normal corresponded to extra-vascular lung water of 5 to 9 ml./kg. body weight. Interstitial oedema (radiological stage I and II) corresponded to extravascular lung water levels of 8 to 12 ml./kg. Differentiation of stages I and II was not possible. During stage III, extra-vascular lung water was 15 to 21 ml./kg. A comparative analyses of these findings revealed a discrepancy of 34%. The reasons for this are discussed.

Adult↗