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Biomedical subjects

A Heuck

Publications and source records attributed to A Heuck.

At least 55 records · Page 3Linked to original sources
PubMed1995

[Fast and ultra-fast sequences in MRI of the pelvis and retroperitoneum].

Fast and ultrafast sequences are crucial prerequisite for optimum diagnostic impact in magnetic resonance (MR) imaging of the pelvis and retroperitoneum. In MR imaging of the pelvis, heavily T2-weighted fast turbo spin echo (TSE) sequences with acquisition times of 2-4 min have widely replaced time-consuming conventional T2-weighted SE sequences due to substantial time savings and better image quality. Fast and ultrafast gradient recalled echo (GRE) sequences are the basis of dynamic contrast-enhanced studies. In MR imaging of the retroperitoneum, fast and ultrafast sequences currently play the most important role as they allow for breath-hold acquisition of a sufficient number of images free of motion artifacts. The current roles of TSE, tubo gradient spin echo (TGSE), GRE and echoplanar imaging (EPI) sequences in MR imaging of the pelvis and retroperitoneum is discussed.

Artifacts↗
PubMed1994

[Fat-suppressing STIR sequences with and without contrast media in the MRT of ENT tumors].

Fat-suppressed STIR (short TI inversion recovery) sequences were compared to plain and contrast-enhanced T1-weighted SE sequences of head and neck tumors. 19 patients underwent MR imaging on a 0.5 Telsa system (T5-II, Philips). STIR imaging parameters: TR/TE = 1000/20 ms, inversion pulse 100 ms. All films were read by four radiologists. The image quality was graded: score from 0 to 5, by means that grade 5 = optimal quality. Sensitivity was 89% in STIR, 96% in SE sequences. Tumor delineation was graded good in the enhanced T1-weighted and enhanced fat suppression images. The unenhanced imaging was superior in STIR (STIR/T1 = 2.8/2.43). The tumor contrast was best in contrast enhanced and plain STIR sequences (STIR contrast = 3.41), and in the contrast enhanced T1-weighted SE (3.33). STIR almost equaled T1 post-contrast in respect of tumour conspicuity, but the sensitivity was lower. STIR can be a supplement to SE, but cannot substitute T1 postcontrast. The combined use is expected to have the highest assessment value.

Adipose Tissue↗
PubMed1994

[MRT of the female pelvis: turbo-spin-echo (TSE) sequences compared to conventional spin-echo sequences at 0.5 tesla].

Markedly T2-weighted MR images of the pelvis can be obtained with TSE sequences using short acquisition times. In order to determine whether TSE sequences at 0.5 Tesla produce diagnostically valuable images, 9 normals and 53 patients with suspected gynaecological tumours were examined with TSE and SE sequences. Visual comparison showed a considerable superiority of the TSE sequences in most respects. The quality of the TSE images was regarded as very good in 82% and good in 18% (SE sequences: 27% very good, 55% good, 18% moderate), delineation of anatomical structures 81% very good and 19% good (SE sequence: 31% very good, 53% good, 16% moderate). TSE sequences were also superior in the detection of pathological changes (87% very good, 13% good) compared with SE sequences (56% very good, 37% good, 7% moderate). Venous plexuses in the parametrium were better demonstrated by SE sequences. There were significantly higher signal to noise ratios (SNR) with TSE sequences for fat, bone marrow (each p < 0.001), and urine (p < 0.05). Using muscle as reference tissue, there were significantly higher signal-difference to noise ratios (SDR) for fat (p < 0.001), and bone marrow (p < 0.0001), the other pelvic organs and tumours showed no significant differences between the SNR and SDR. TSE sequences are well suited to replace SE sequences in the MR diagnosis of gynaecological tumours.

Adolescent↗
PubMed1994

[MR tomography in staging of carcinomas of the uterus].

Magnetic resonance imaging (MRI) has proven to be a suitable imaging modality for the evaluation of uterine neoplasms. In contrast to computed tomography and ultrasound, MRI allows multiplanar observer-independent imaging of the whole female pelvis with high tissue-specific contrast. This article reviews the advantages and limitations of MRI in the staging of endometrial and cervical carcinoma, focusing on MRI with reference to other imaging modalities. New technical developments are discussed and an imaging approach for these tumor types is suggested.

Cervix Uteri↗
PubMed1994

[MRI in orthopedics: diagnosis of joint disorders].

For the visualization of joint structures, magnetic resonance imaging (MRI) has definite advantages over other imaging modalities. High soft tissue contrast and multiplanar capabilities contribute to adequate representation of the joints. With surface and special coils as well as high gradient field strengths, superior spatial resolution can be achieved, thus allowing for depiction of fine anatomical details. Newly developed pulse sequences, especially with fat suppression techniques and utilization of paramagnetic contrast agents (gadolinium complexes) have improved image contrast. Examination techniques, results and diagnostic value of MRI in various joints are discussed. Close cooperation between orthopaedic surgeons and radiologists is mandatory for effective and economically acceptable use of MRI in the diagnosis of joint disorders.

Ankle Joint↗
PubMed1992

[Computed tomographic assessment of breathing-induced "pseudo" pneumoperitoneum].

The differentiation between a "pseudo" pneumoperitoneum and a pneumoperitoneum due to a perforation may be difficult in unconscious or ventilated patients. The use of CT for differentiating between extraperitoneal and intraperitoneal air is demonstrated by three examples in whom air below the diaphragm was shown by conventional radiographs. CT can prove the extraperitoneal position of an air crescent below the diaphragm in cases of "pseudo" pneumoperitoneum. CT will also show that extraperitoneal air does not rise in the way that true peritoneal air will do when the patient is supine. In this position the viscera therefore do not fall backwards in the presence of a "pseudo" pneumoperitoneum.

Adult↗
PubMed1992

[MRT of the hand and wrist of sport climbers. Imaging of injuries and consequences of stress overload].

The hands and wrists of 20 top-level rock climbers with sports injuries and overstress abnormalities were compared with the hands and wrists of 10 normal volunteers. They were all studied with MR imaging at 1.5 T. The imaging protocol included spin-echo and gradient-echo sequences with 1- to 5-mm-thick contiguous slices in the axial, coronal and/or sagittal planes, depending on the location and nature of the suspected injury. Typical hand and wrist lesions depicted with MRI in climbers consisted of anular ligament tears, lesions of the flexor tendons, tenosynovitis, ganglion cysts, joint effusion and functional carpal tunnel syndrome. The MRI findings on these abnormalities were compared to normal findings and those with ultrasound and plain films. In addition, hypertrophic changes in the muscles, tendons, ligaments, and bones of top-level rock climbers were assessed morphometrically. MRI proved to be the superior imaging modality in the diagnosis of sports injuries and overstress abnormalities of the hand and wrist in rock-climbing athletes.

Adult↗
PubMed1991

[The diagnostic accuracy of MRT in cruciate ligament injuries].

Lesions of the anterior cruciate ligaments may be demonstrated by MRI with an accuracy of 99%. Standardised technique with sagittal and coronal projections produces excellent results. Localisation of the site of rupture can be achieved in 95% of cases. MRI provides a valuable method for diagnosing lesions of the cruciate ligaments.

Adolescent↗
PubMed1990

[Imaging of epiphyseolysis of the femur head in the magnetic resonance tomogram].

The diagnosis of epiphyseolysis of the femoral head in its early stages is often unclear when using conventional radiography. In order to obtain additional information, we examined seven patients by means of MRT. In all cases the T1-weighted sequences showed widened, ill-defined epiphyseal plates. The epiphyseal displacement was shown accurately by sections of the sagittal plane. T2-weighted sequences showed the presence of an effusion in the hip joints of five patients. In all patients there was increased signal intensity in the metaphysis and in the femoral neck and head. The increased signal intensity appears to be an early sign for the presence of an epiphyseolysis.

Adolescent↗
PubMed1990

[Magnetic resonance tomography of the shoulder. Possibilities of over interpretation of normal findings].

In order to test the criteria for abnormalities of the shoulder as seen on MR, 30 normal shoulders were examined. The examination included T1, proton and T2-weighted SE sequences and T2*-weighted FE sequences, using transverse, oblique coronary and oblique sagittal planes. In 57% there was increased signal intensity in the tendon of the rotator cuff; this might have been interpreted as a rupture of the cuff or tendinitis. Anatomical examination suggests that the finding is due to a normal layer between the long head of the biceps and the tendon joint complex. The anterior glenoid labrum could not be clearly delineated in 57% and the posterior labrum in 5%. In two cases there was a superior, postero-lateral defect in the head of the humerus. The currently accepted criteria for the MRT diagnosis of shoulder abnormalities need to be critically re-evaluated.

Adolescent↗
PubMed1990

[NMR tomography compared to skeletal scintigraphy after traumatic vertebral body fractures].

MRI and scintigraphy were compared in 73 patients with 104 vertebral fractures aged between three days and 64 months. MRI was performed at 0.5 Tesla and 1.5 Tesla using T1- and T2-weighted spin-echo sequences. Isotope uptake was divided into four grades (normal, mild, moderate and marked increase). 92% of cases aged 0-6 months showed increased signal intensity on T2 sequences. This finding reflects edema in the bone. All these cases showed moderate or markedly increased uptake in 86%. The increased signal intensity in T2 spin-echo images provides a criterion for differentiating new from old fractures. The identification of normal fatty marrow in 91% of fractured vertebrae provides an important means for distinguishing traumatic from neoplastic fractures. One can also demonstrate bleeding, fatty change and sclerotic bone. MRI is less sensitive than scintigraphy, but more specific in following the posttraumatic healing process.

Adolescent↗