Wolfgang Steinbrich

Blood Oxygenation Level–Dependent Magnetic Resonance Imaging of the Skeletal Muscle in Patients With Peripheral Arterial Occlusive Disease

Background— Blood oxygenation level–dependent (BOLD) magnetic resonance imaging (MRI) has been used to measure T2* changes in skeletal muscle tissue of healthy volunteers. The BOLD effect is assumed to primarily reflect changes in blood oxygenation at the tissue level. We compared the calf muscle BOLD response of patients with peripheral arterial occlusive disease (PAOD) to that of an age-matched non-PAOD group during postischemic reactive hyperemia. Methods and Results— PAOD patients (n=17) with symptoms of intermittent calf claudication and an age-matched non-PAOD group (n=11) underwent T2*-weighted single-shot multiecho planar imaging on a whole-body magnetic resonance scanner at 1.5 T. Muscle BOLD MRI of the calf was performed during reactive hyperemia provoked by a cuff-compression paradigm. T2* maps were generated with an automated fitting procedure. Maximal T2* change (&Dgr;T2*max) and time to peak to reach &Dgr;T2*max for gastrocnemius, soleus, tibial anterior, and peroneal muscle were evaluated. Compared with the non-PAOD group, patients revealed significantly lower &Dgr;T2*max-values, with a mean of 7.3±5.3% versus 13.1±5.6% (P<0.001), and significantly delayed time-to-peak values, with a mean of 109.3±79.3 versus 32.2±13.3 seconds (P<0.001). Conclusions— T2* time courses of the muscle BOLD MRI signal during postocclusive reactive hyperemia revealed statistically significant differences in the key parameters (&Dgr;T2*max; time to peak) in PAOD patients compared with age-matched non-PAOD controls.

Accuracy of multidetector row computed tomography for the diagnosis of acute bowel ischemia in a non-selected study population

The diagnostic accuracy of multidetector row computed tomography for the prospective diagnosis of acute bowel ischemia in the daily clinical routine was analyzed. Two hundred ninety-one consecutive patients with an acute or subacute abdomen, examined by MDCT over a time period of 5 months, were included in the study. All original CT diagnoses made during the daily routine by radiological generalists were compared to the final diagnoses made by using all available medical information from endoscopies, surgical interventions, autopsies and follow-up. Finally, all CT examinations of patients with an initial CT diagnosis or a final diagnosis of bowel ischemia were reread by a radiologist specialized in abdominal imaging in order to analyze the CT findings and the reasons for initially false negative or false positive CT readings. Twenty-four patients out of 291 (8.2%) had acute bowel ischemia. The age of affected patients ranged from 50 to 94 years (mean age: 75.7 years). Eleven patients were male, and 13 female. Reasons for acute bowel ischemia were: arterio-occlusive (n=11), non-occlusive (n=5), strangulation (n=2), over-distension (n=3) and radiation (n=3). The prospective sensitivity, specificity, PPV and NPV of MDCT for the diagnosis of acute bowel ischemia in the daily routine were 79.17, 98.51, 90.48 and 98.15%. MDCT reaches a similarly high sensitivity in diagnosing acute bowel as angiography. Furthermore, it has the advantage of being helpful in most of its clinical differential diagnoses and of being less invasive with the consecutive possibility of being used earlier in the diagnostic process with all the resulting positive effects on the patients prognosis. Therefore, nowadays MDCT should probably be used as the first step imaging modality of choice in patients with suspected acute bowel ischemia.

Chronic post-traumatic osteomyelitis of the lower extremity: comparison of magnetic resonance imaging and combined bone scintigraphy/immunoscintigraphy with radiolabelled monoclonal antigranulocyte antibodies

Abstractu2002Objective. A retrospective study of the validity of combined bone scintigraphy (BS) and immunoscintigraphy (IS) using 99mTc-labelled murine antigranulocyte antibodies (MAB) and magnetic resonance imaging (MRI) in chronic post- traumatic osteomyelitis.nDesign and patients. The results of MRI and combined BS/IS of 19 lesions in 18 patients (13 men, 5 women; mean age 45 years, range 27–65 years) were independently evaluated by two radiologists and one nuclear medicine physician with regard to bone infection activity and extent. The patient group was a highly selective collection of clinical cases: the average number of operations conducted because of relapsing infection was eight (range 2–27), the average time interval between the last surgical intervention and the present study was 6.5 years (range 3 months to 39 years), and from the first operation was 14 years (range 1.5–42 years). Interobserver agreement on MRI was measured by kappa statistics. Sensitivity, specificity, accuracy, positive predictive value (PPV) and negative predictive value (NPV) were calculated for MRI and the nuclear medicine studies.nResults. For MRI/nuclear medicine, a sensitivity of 100%/77%, a specificity of 60%/50%, an accuracy of 79%/61%, a PPV of 69%/58% and a NPV of 100%/71% were calculated. Four MR examinations were false positives because of postsurgical granulation tissue. A high degree of interobserver agreement was found on MRI (κ=0.88). A low-grade infection was missed on two scintigrams, while four were false positive because of ectopic haematopoietic bone marrow, and in one examination the anatomical distortion resulted in an inaccurate assignment of the uptake leading to false positive findings. Image analysis was frequently hindered by susceptibility artefacts due to residual abrasions of metallic implants after removal of orthopaedic devices (15/18 patients); this led to limited assessment in 17% (3/18 patients).nConclusion. Acute activity in a chronic osteomyelitis can be excluded with high probability if the MRI findings are negative. In the first postoperative year fibrovascular scar cannot be distinguished accurately from reactivated infection on MRI and scintigraphy may improve the accuracy of diagnosis. MRI is more sensitive in low-grade infection during the later course than combined BS/IS. Scintigraphic errors due to ectopic, peripheral, haematopoietic bone marrow can be corrected by MRI.

Clinical utility of contrast-enhanced MR angiography

Abstract. MR angiography (MRA) is a technique under ongoing discussion. Its non-invasiveness and sensitivity to flow irregularities make it an investigational technique which is easy to apply but which does not always lead to comprehensive results. It requires special skill to perform and also experience for correct interpretation of the results. The lengthiness of the procedure combined with certain physical properties tends to limit its use to mostly neurovascular applications. With the introduction of ultrafast MRA in conjunction with peripheral bolus-injection of extracellular contrast media, a new approach to the imaging of such regions as the thoracic and abdominal vasculature not to mention other vascular territories has become possible. In this paper, considerations of bolus and measurement optimization and timing protocols for dedicated indications are presented together with an overview on the experience acquired to date for CE-MRA of the carotid artery, mediastinal and pulmonary vessels, abdominal vasculature, and peripheral vessels. The main advantage of ultrafast CE-MRA is that patients are subjected to much more tolerable breath-hold investigations with the result that physiological motion such as peristalsis or major pulsation is minimised.

A new rotational thrombectomy catheter: System design and first clinical experiences

AbstractPurpose: To describe a new catheter for the percutaneous mechanical removal of fresh and organized thrombi, and to assess its efficacy and safety in vitro and in vivo.n Methods: The catheter consists of a coated stainless steel spiral that rotates at 40,000 rpm over a guidewire inside the whole length of an 8 Fr, single-lumen, polyurethane catheter, driving a dual-blade cutting crown. Abraded occlusion material is sucked into the catheter head through distal side holes and transported by the spiral into a reservoir at the proximal end. The efficacy of the device was tested in arterial models and fresh bovine carotid arteries (n=72). In a clinical pilot study 10 patients (8 women, 2 men; mean age 70.6 ±10.1 years) with occlusions of the superficial femoral artery (2–12 cm, mean 5.8 cm), not older than 4 weeks, underwent thrombectomy with the new catheter.n Results: In arterial models and bovine cadaver arteries the catheter completely removed fresh thrombi. Occlusion material of higher consistency was cut into particles of 100–500 μm and transported outside. Thrombectomy was successful and vessel patency restored in all 10 patients. The ankle/brachial pressure index significantly (p<0.0005) increased from 0.41±0.18 before intervention to 0.88±0.15 after 48 hr and to 0.84±0.20 after 3 months. Two reocclusions occurred within 14 days after the intervention.n Conclusion: Thrombectomy with the new device appears to be feasible and safe in patients with acute and subacute occlusions of the femoropopliteal artery.

Technologieintegration und Prozessmanagement Konzept und Implementierung einer neuartigen Plattform für einzeitige Diagnostik und Therapie des akut Kranken und Verletzten sowie für elektive computerassistierte Chirurgie (CAS)

ZusammenfassungModerne Bildgebung und Computertechnologie gewinnen innerhalb der Chirurgie einen immer höheren Stellenwert. Dies gilt sowohl für die elektive Chirurgie als auch für die Notfallbehandlung. Die Integration der Technologien und die dadurch mögliche Optimierung der Prozessabläufe hinken dieser Entwicklung jedoch stark hinterher. Eine neue diagnostisch-therapeutische Plattform soll dieses Defizit wettmachen. Die Plattform besteht aus einer voll ausgebauten Operationssaalumgebung mit integrierter navigationsfähiger Computertomographie, einer Angiographieanlage und einem speziell dafür entwickelten Patiententisch. Sie dient sowohl der elektiven Diagnostik als auch der Diagnostik und Therapie polytraumatisierter Patienten an einem Ort (“one stop shop”) und der computerassisitierten Chirurgie (CAS). Indem die Technologie zum Patienten und nicht der Patient zur Technologie gebracht wird, können zeitraubende, potenziell gefährliche Transporte und Umlagerungen sowie teures Personal eingespart werden. Navigationstechnologie und hochauflösende intraoperative Bildgebung erweitern das Spektrum der minimal invasiven Chirurgie.AbstractModern imaging and computer technology gain more and more importance in surgery. This is true for elective and emergency diagnosis and treatment. However integration of technology and optimization of process management is severely behind. A new diagnostic-therapeutic platform should balance this deficit. The platform is composed of a fully equipped operation room environment with integrated high end computer-tomography with navigation, a digital subtraction angiography and an OR- and imaging-table particularly developed for this set-up. The platform may be used for elective diagnosis, for diagnosis and therapy in polytraumatized patients in one and the same location (one stop shop) and for computer assisted surgery (CAS). Bringing the technology to the patient and not the patient to the technology can save time consuming and potentially dangerous transports and expensive personnel can be reduced. Navigation-technology and high quality intra-operative imaging expand the spectrum of minimally invasive surgery.

Colonic involvement in non-necrotizing acute pancreatitis: correlation of CT findings with the clinical course of affected patients

Abstract. The purpose of this study was to describe CT findings of colonic involvement in acute non-necrotizing pancreatitis and to analyze the correlation between colonic wall thickening at CT and the clinical course of these patients. The CT examinations of 19 consecutive patients with acute non-necrotizing pancreatitis who were not treated with antibiotics initially were analyzed retrospectively. The severity of acute pancreatitis was categorized according to the CT severity index (CTSI) and the presence of colonic wall thickening at the initial CT was compared with the clinical course of all patients. Seven of 11 patients with a CTSI of 4 showed a colonic wall thickening, whereas the remaining patients with a CTSI of 4 (n=4), CTSI of 3 (n=5), and CTSI of 2 (n=3) showed no colonic abnormalities at CT. Patients with colonic wall thickening presented more often with fever, showed higher levels of infectious parameters, needed more often antibiotic therapy, and had more requests for additional CT examinations and CT-guided fluid aspirations as well as a longer duration of hospital stay as compared with patients without colonic wall involvement, even if the latter presented with the same CTSI initially. It is well known that translocation of the colonic flora may significantly influence the clinical course of patients with acute pancreatitis, and our results indicate that patients with acute pancreatitis who present with colonic wall thickening at CT have an increased risk for a complicated clinical course regarding systemic infection.

Sonographische Diagnostik der Schilddrüse

In Anbetracht ihrer oberflachlichen Lage bietet sich die Schilddruse bestens fur die Ultraschalluntersuchung an. Die Sonographie der Schilddruse ist eine zuverlassige Abklarungsmethode bei verschie...

Diagnostic Imaging of the Thyroid and Radioiodine Therapy

According to its superficial anatomic location, the thyroid gland may easily be assessed by sonography. Linear transducers with a width of 7.5–9 cm and frequencies of around 10 MHz are used. Sonography of the thyroid gland should also always be combined with a sonography of the surrounding soft tissues and of the cervical vessels. It allows the exact measurement of the thyroid volume and assessment of the parenchymal texture of the thyroid gland with identification of diffuse or focal abnormalities of the gland itself and of potential abnormalities within the surrounding structures.