Endoscopic surgery: talent or training?

PURPOSE: There are two groups of undergraduate students involved in endoscopic surgery with different degrees of experience: average and more experience. This study proves whether the subjective impression of the laparoscopic trainer is verifiable and which factors influence extreme talent. METHODS: 21 medical students of the eighth term of the University of Witten-Herdecke participated in the study. On their first course day, students got instructed in suturing and knot technique. They were then required to tie a maximum of five knots within 2 h. After a week, students repeated this procedure. Time used for tying knots was stopped. RESULTS: Regarding the time students used for their first knots, great differences were provable (7-8 min, average 23 min). However, an adaption of the knotting time was noticed at the end of the first course day. This was confirmed during the second course day. Neither acquired factors (music, sport, etc.) nor individual factors (visual acuity, handedness, etc.) had any impact on the time used for knotting. Merely, one advantage was seen with the first knots with the factors of playing the guitar and having a more than 10-h surgical previous experience. Knotting times leveled off at 95% to less than 10 min, though. DISCUSSION: Neither normally talented nor extremely talented junior surgeons could be noticed, and so could not the co-factors providing an advantage or disadvantage for surgery, respectively. All prospective surgeons can learn defined tasks (knots) by short interval training, and thus show similarly good results after a few repetitions.

Flow-targeted inversion-prepared b-TFE coronary MR angiography: initial results in patients.

PURPOSE: Visualization of coronary blood flow in the right and left coronary system in volunteers and patients by means of a modified inversion-prepared bright-blood coronary magnetic resonance angiography (cMRA) sequence. MATERIALS AND METHODS: cMRA was performed in 14 healthy volunteers and 19 patients on a 1.5 Tesla MR system using a free-breathing 3D balanced turbo field echo (b-TFE) sequence with radial k-space sampling. For magnetization preparation a slab selective and a 2D selective inversion pulse were used for the right and left coronary system, respectively. cMRA images were evaluated in terms of clinically relevant stenoses (< 50 %) and compared to conventional catheter angiography. Signal was measured in the coronary arteries (coro), the aorta (ao) and in the epicardial fat (fat) to determine SNR and CNR. In addition, maximal visible vessel length, and vessel border definition were analyzed. RESULTS: The use of a selective inversion pre-pulse allowed direct visualization of the coronary blood flow in the right and left coronary system. The measured SNR and CNR, vessel length, and vessel sharpness in volunteers (SNR coro: 28.3 +/- 5.0; SNR ao: 37.6 +/- 8.4; CNR coro-fat: 25.3 +/- 4.5; LAD: 128.0 cm +/- 8.8; RCA: 74.6 cm +/- 12.4; Sharpness: 66.6 % +/- 4.8) were slightly increased compared to those in patients (SNR coro: 24.1 +/- 3.8; SNR ao: 33.8 +/- 11.4; CNR coro-fat: 19.9 +/- 3.3; LAD: 112.5 cm +/- 13.8; RCA: 69.6 cm +/- 16.6; Sharpness: 58.9 % +/- 7.9; n.s.). In the patient study the assessment of 42 coronary segments lead to correct identification of 10 clinically relevant stenoses. CONCLUSION: The modification of a previously published inversion-prepared cMRA sequence allowed direct visualization of the coronary blood flow in the right as well as in the left coronary system. In addition, this sequence proved to be highly sensitive regarding the assessment of clinically relevant stenotic lesions.

[Isolated bilateral Sternocostoclavicular Hyperostosis (SCCH) with a pathological clavicular fracture--a 10-year follow-up]. / Isolierte, bilaterale sternokostoklavikuläre Hyperostose (SCCH) mit pathologischer Klavikulafraktur--Ein Verlauf über 10 Jahre.

The presented case demonstrates the clinical and radiological course of a woman suffering from bilateral sternocostoclavicular hyperostosis (SCCH) from early changes to a spontaneous clavicula fracture after 10 years. SCCH is characterised by a chronic recurrent painful swelling of the sternoclavicular region due to an aseptic inflammation and hyperostosis of the clavicula, sternum, upper ribs and the adjacent soft tissues. Frequently the picture is accompanied by cutaneous and other skeletal symptoms. The disease can be part of the SAPHO (synovitis, acne, pustulosis, hyperostosis, osteitis) syndrome. The chronic process is represented by the typical "bull horn sign" in a bone scan. NSAIDS should represent the first line treatment.

[High-resolution T1-weighted MR-lymphography of inguinal lymph nodes after interstitial application of Gadomer-17 in animal experiments]. / Hochauflösende T1-gewichtete MR-Lymphographie inguinaler Lymphknoten nach interstitieller Applikation von Gadomer-17 im Tierexperiment.

PURPOSE: To evaluate the microstructural anatomy of inguinal lymph nodes in pigs after interstitial MR-lymphography with the dendritic contrast agent Gadomer-17. MATERIAL AND METHODS: High-resolution T1-weighted MR-lymphography was performed in inguinal lymph nodes of 10 domestic pigs (39 - 46 kg) after subcutaneous injection of 10 mumol/kg body weight Gadomer-17 in the hind legs of the animals. A 1.5T MR scanner and a ring-shaped surface coil were used. Two different high-resolution gradient-echo sequences with additionally reconstructed maximum-intensity projections were evaluated in a total of 20 lymph nodes. The high-resolution MR-findings were correlated with the histologic sections of the excised inguinal lymph nodes. RESULTS: Coronal T1-weighted 3D gradient-echo images (TR = 20 msec, TE = 6.1 - 8.3 msec, FA = 20 degrees ) with a slice thickness of 1 mm, a field-of-view of 120 mm and a matrix size of 256 x 256 (reconstructed to 1024 x 1024 voxels) yielding a reconstructed in-plane resolution of 117 x 117 microm (2) were best suited for the high-resolution MR lymphography of inguinal lymph nodes and enabled the differentiation of the hyperintense lymph node sinuses and hypointense lymphoid parenchyma of each lymph node (100 %). Even dilated lymphatic vessels evident in the histologic specimen were best demonstrated on the MIP images. CONCLUSION: High-resolution interstitial MR lymphography with Gadomer-17 allows the visualization of different tissue compartments of inguinal lymph nodes. This new technique is feasible on a routine 1.5T scanner and may offer potential for the detection of micrometastases in lymph nodes of cancer patients.

[Renovascular hypertension--diagnosis and therapy]. / Renovaskuläre Hypertonie. Diagnostik und Therapie.

Atherosclerotic renal artery stenosis accounts for most cases of renovascular hypertension (RVH). Hypertensive patients with clinical features suggesting RVH should be submitted to further noninvasive evaluation including duplex Doppler ultrasonography, CT- or MR angiography. Invasive evaluation by contrast-enhanced angiography confirms the diagnosis of renal artery stenosis. However, neither diagnostic test reliably predicts the course of hypertension after revascularisation. The therapeutic approach in hypertensive patients with hemodynamically important renal artery stenosis includes medical or invasive therapy (renal percutaneous transluminal angioplasty, PTRA; renal arterial stent placement, PTRAS; surgical revascularisation). Randomized trials comparing invasive and conservative approaches demonstrated no differences in blood pressure control or renal function. Only patients with clear clinical indications should be submitted to interventional procedures as PTRA, PTRAS and surgical vascular intervention.

Multi-slice CT for visualization of acute pulmonary embolism: single breath-hold subtraction technique.

PURPOSE: The purpose of our preliminary animal study was to evaluate the feasibility of a new subtraction technique for visualization of perfusion defects within the lung parenchyma in segmental and subsegmental pulmonary embolism (PE). MATERIALS AND METHODS: In three healthy pigs, PE were artificially induced by fresh human clot material. Within a single breath-hold, CT angiography (CTA) was performed on a 16-slice multi-slice CT scanner (SOMATOM Sensation 16; Siemens, Forchheim, Germany) before and after intravenous application of 80 mL of contrast-medium, followed by a saline chaser. Scan parameters were 120 kV and 100 mAs (eff.), using a collimation of 16 x 1.5 mm and a table speed/rot. of 36 mm (pitch: 1.5; rotation time: 0.5 s). A new 3D subtraction technique was developed, which is based on automated segmentation, non-linear spatial filtering and non-rigid registration. Data were analysed using a color-encoded "compound view" of parenchymal enhancement and CTA information displayed in axial, coronal and sagittal orientation. RESULTS: Subtraction was technically feasible in all three data sets. The mean scan time for each series was 4.7 s, interscan delay was 14.7 s, respectively. Therefore, an average breath-hold of approximately 24 s was required for the overall scanning procedure. Downstream of occluded segmental and subsegmental arteries, perfusion defects were clearly assessable, showing lower or missing enhancement compared to normally perfused lung parenchyma. In all pigs, additional peripheral areas with triangular shaped perfusion defects were delineated, considered typical for PE. CONCLUSIONS: Our initial results from the animal model studied show that perfusion imaging of PE is feasible within a single breath-hold. It allows a comprehensive assessment of perfusion deficits as the direct proof of a pulmonary embolus, can be combined with an indirect visual quantification of the density changes in the adjacent lung tissue.

[MR imaging of lung ventilation with aerosolized gadolinium-chelates]. / MR-Bildgebung der Lungenventilation mittels aerosolierter Gadolinium-Chelate.

PURPOSE: To evaluate the feasibility of magnetic resonance assessment of human lung ventilation with aerosolized Gd-chelates in healthy volunteers. MATERIALS AND METHODS: Five healthy adults (mean age 37 years) were studied with a 1.5 T unit. The volunteers were instructed to inhale the aerosol through an airtight facial mask for 10 minutes. The aerosol was generated with a jet-type small particle nebulizer with attached heater. Ventilation imaging was performed using a respiration-gated dynamic T1-weighted turbo spin echo sequence (T(R) = 199 ms, T(E) = 8.5 ms, 12 signal averages, slice thickness 10 mm). Pulmonary signal intensity changes were calculated before and after nebulization. RESULTS: The investigation was successfully carried out in all volunteers. An acute or delayed allergic reaction to the aerosolized contrast medium was not observed. In 4 of 5 experiments (80 %), a homogeneous signal intensity increase was readily visualized with an average signal increase of 35 % after 10 minutes; in one experiment, the aerosol distribution was slightly heterogeneous. CONCLUSION: The results of the presented phase I clinical study demonstrate the feasibility of human ventilation imaging with aerosolized Gd-chelates for the first time. More trials with a larger number of healthy subjects and patients are needed before the clinical introduction of Gd-based ventilation MR imaging of the lungs.

[Interstitial T1-weighted MR lymph fistulography with Gadomer-17 in an experimental animal model]. / Interstitielle T1-gewichtete MR-Lymphfistulographie mittels Gadomer-17 im Tierexperiment.

PURPOSE: To visualize and localize fistulas of the thoracic duct with interstitial T 1 -weighted MR lymphography using Gadomer-17. MATERIALS AND METHODS: In 10 domestic pigs, leaks of the thoracic duct were created surgically or interventional-radiologically. The lymphatic leakage was located within the abdominal portion of the thoracic duct in 5 pigs, within the thoracic portion of the thoracic duct in 3 pigs, and in both, abdominal and thoracic portions of the thoracic duct, in 2 pigs. Subsequently, 10 micro mol/kg KG Gadomer-17 (1.5-1.8 ml) was administered interstitially in both hind legs of the animals. MR lymphography was performed with a 1.5 T MR unit using two different 3D gradient echo sequences before and 10 - 90 minutes after administration of contrast material. RESULTS: Leaks within the abdominal portion of the thoracic duct were directly visible as opacified fistulas. Indirect signs of active lymphatic fistulas were increasing extravasations of contrast material and free abdominal fluid. The 3D gradient echo sequence with the highest planar resolution (TR = 8,7 - 8,8 ms, TE = 4,2 - 4,3 ms, FA = 40 degrees, matrix size = 327 x 512) was best suited for distinct delineation of the lymphatic system and detailed demonstration of the thoracic duct fistulas. Intrathoracic leaks could not be demonstrated by MR lymphography due to reduced lymphatic flow or extravasated contrast medium at the abdominal puncture site. CONCLUSION: Interstitial MR lymphography with Gadomer-17 allows sensitive detection and localization of abdominally located leaks of the thoracic duct.

[Quantification of cardiac function with multislice spiral CT using retrospective EKG-gating: comparison with MRI]. / Quantifizierung der Herzfunktion in der Mehrschicht Spiral CT mit retrospektivem EKG-Gating: Vergleich zur Kernspintomographie.

PURPOSE: To quantify left ventricular function derived from retrospectively ECG-gated multislice spiral CT (MSCT) data sets in comparison to MRI. MATERIALS AND METHODS: In 16 patients (14 males, 2 females, mean age 56.8 +/- 11.5 years), retrospectively ECG-gated MSCT angiography of the coronary arteries and breath-hold steady state free precession cine MRI were performed. From MSCT data-sets, 20 axial image series were reconstructed every 5 % of the RR interval. Multiplanar images were reformatted in the short axis orientation from axial images. End-systolic and end-diastolic images were selected. From these images end-systolic volume (ESV), end-diastolic volume (EDV) and stroke volume (SV) as well as the ejection fraction (EF) and myocardial mass (MM) were determined using the Simpson's method and compared with MRI. Furthermore, image quality was assessed for both imaging modalities using a four point grading scale. RESULTS: All parameters were found to have an excellent correlation between MSCT and MRI data (Pearson's correlation coefficient 0.95 - 0.99), without clinically relevant differences between both modalities. On average, the difference between both methods was 0.5 ml for ESV, 0.8 ml for EDV, 1.3 ml for SV, 0.9 % for EF and 2.3 g for MM. Image quality was slightly better for MRI (1.5 +/- 0.65) than for MSCT (1.64 +/- 0.74). CONCLUSION: Retrospectively ECG-gated MSCT angiography can not only visualize the coronary arteries but also enables precise quantification of the left ventricular function from the same MSCT data set.

[Maxillary sinus examination after sinus floor elevation combined with autologous onlay osteoplasty]. / Kieferhöhlenuntersuchung nach Sinusbodenelevation kombiniert mit autologer Onlay-Osteoplastik.

BACKGROUND: Complication rates after sinus floor augmentation of up to 10% are mentioned in literature, often when heterologous bone implants are used. The aim of our retrospective study was to determine the complication rate involving the maxillary sinus of patients treated with autologous spongiosa. PATIENTS AND METHODS: In 46 patients with an absolute maxillary atrophy (61% female, 39% male, mean age 49 years), a sinus floor augmentation, if necessary combined with an onlay bone graft of the iliac crest, was performed. Implants (Brånemark) were placed in a two-stage procedure after 3-6 months. Prior to surgery, a panoramic film was made for diagnosis and treatment planning; in addition, a sinus X-ray was taken when disease of the maxillary sinus was suspected. panoramic radiography was routinely taken after surgery. A clinical and radiological follow-up examination was performed after 6-12 months, and the patients answered a questionnaire. This study also included evaluation of operation reports and case histories. Ultrasound as well as magnetic resonance imaging to prevent radiation exposure were performed additionally. RESULTS: In spite of perforation of the maxillary sinus mucosa in about 25%, removal of the bone graft due to inflammation was not necessary. A transient sinusitis developed in 2%. The implant loss rate (3 out of 154) may be called small. DISCUSSION: Even though alternative heterologous graft materials exist, maxillary sinus floor elevation with autologous bone graft is still a safe option. Changes of the maxillary sinus are detectable in a small percentage, relatively often due to preexisting unrecognized or subclinical diseases of the maxillary sinus. Magnetic resonance imaging is, in spite of the high financial and technical effort required, a serious alternative to computed tomography. The combination of autologous bone graft with calcium phosphate ceramics, platelet-rich plasma, or synthetic bone growth factors should be tested as an alternative treatment method.

T1-weighted MR-lymphography after intramammary administration of Gadomer-17 in pigs.

PURPOSE: To evaluate the enhancement of regional lymph nodes and lymphatic vessels after intramammary injection of Gadomer-17. MATERIALS AND METHODS: T1-weighted MR-lymphography was performed in 8 domestic pigs after intramammary injection of 5 - 10 micromol/kg bodyweight (bw) Gadomer-17 on a 1.5 T-MR scanner. T1-weighted 3D gradient-echo images were acquired 10 to 120 minutes after contrast material injection in coronal and sagittal planes. The contrast enhancement of the draining lymphatic system was qualitatively assessed by two radiologists applying a three grade scale. RESULTS: T1-Weighted MR-lymphography after intramammary injection of Gadomer-17 was feasible in each pig. A dose of 5 micromol/kg body weight Gadomer-17 was best suited for MR-lymphography of the mammary line and the draining lymphatic system. Enhancement of regional lymph nodes and lymphatic vessels was classified as good in 5, and excellent in three cases. CONCLUSIONS: Intramammary injection of Gadomer-17 allows for good quality T1-weighted MR-lymphography of mammary gland draining regional lymph nodes and lymphatic vessels. This new technique might offer potential for the evaluation of the sentinel lymph node in patients with breast cancer.

[Differentiation of serous and purulent fluids in vitro and in vivo by means of diffusion-weighted MRI]. / Differenzierung seröser und putrider Flüssigkeiten in vitro und in vivo mit diffusionsgewichteter MRT.

AIM: The aim of this study was to test the feasibility for differentiation of serous fluid collections and abscess fluid with diffusion-weighted imaging and to compare three different diffusion sequences. MATERIAL AND METHODS: Thirteen puncture samples (6 serous, 7 purulent) and 19 patients with either serous fluid collections (n = 12) or abscesses (n = 7) were examined with diffusion-weighted spin-echo (SE), stimulated-echo (STE), and fatsuppressed SE (SE-SPIR) sequences. For in vitro studies 4 different b-factors (0, 87, 355, 798 s/mm2 in SE and SE-SPIR and 0, 51, 204, 460 s/mm2 in STE) were chosen and the apparent diffusion coefficient (ADC) was calculated. For in vivo measurements identical sequences with two b-factors (0.598 s/mm2 in SE and SE-SPIR and 0.360 s/mm2 in STE) were applied and the normalized signal attenuation was calculated. A navigator-echo technique and peripheral pulse triggering was used for motion artifact reduction. RESULTS: The in vitro study yielded an ADC of serous fluid, which was close to that of free water, whereas for purulent fluid a significantly lower ADC was calculated. During in vivo examinations, serous fluids showed a strong signal attenuation (down to 22-32% of basic value) compared to a minor signal attenuation in purulent fluids (down to 86-94% of basic value) (p < 0.05). CONCLUSIONS: In summary, with all three investigated diffusion schemes serous and purulent fluids can be clearly differentiated.

Unilateral absence of the left pulmonary artery associated with coronary-to-bronchial artery anastomosis.

Unilateral absence of the pulmonary artery and bronchial-to-coronary artery anastomosis are rarely described congenital vascular anomalies. The authors report a case of a 49-year-old female presenting with both anomalies. The presenting symptoms and pertinent diagnostic imaging are described, including conventional radiographs, angiography, computed tomography, and magnetic resonance imaging, and the therapeutic options available are discussed.

[MRT of experimental liver abscesses: a comparison of a new blood pool contrast medium with gadolinium-DTPA in animal experiments]. / MRT experimentell induzierter Leberabszesse--Vergleich eines neuen Blutpoolkontrastmittels mit Gadolinium-DTPA in einem Tiermodell.

PURPOSE: In an experimental pyogenic liver abscess model, the signal intensities were compared intraindividually and interindividually after the application of a new blood pool contrast agent, 24-gadolinium-DTPA (diethylenetriamine-pentaacetic acid) cascade polymer, and after the application of gadopentetate dimeglumine. METHODS: In 20 rabbits with experimentally induced liver abscesses, the relative signal intensities of the liver, abscess centre, abscess wall and portal vein were assessed before and between 30 seconds and 60 minutes after injection of a 25 mumol/kg dose of gadolinium polymer and of 100 mumol/kg of gadolinium-DTPA, respectively. Measurements were performed at 1.5 Tesla, using a head coil and a Flash-2-D sequence. RESULTS: The interindividual comparison (unpaired T-test, p < 0.05) yielded significant differences of the relative signal intensities of the abscess centre (at any time point after contrast-media application), abscess wall (between 15 and 60 minutes after contrast media application), and portal vein (between 30 seconds and 7.5 minutes after contrast media application). The interindividual comparison showed a significantly higher abscess centre-liver contrast (between 30 seconds and 12.5 minutes after contrast media application) and a significantly higher abscess wall-centre contrast (between two and 7.5 minutes after contrast media application) after the application of gadolinium polymer compared with gadopentetate dimeglumine. CONCLUSION: In this animal model, the higher abscess centre-liver contrast after the application of gadolinium polymer was the basis for a better and prolonged visibility of the abscesses, as compared with images acquired after injection of gadopentetate dimeglumine.

Differentiation of spontaneous canine breast tumors using dynamic magnetic resonance imaging with 24-Gadolinium-DTPA-cascade-polymer, a new blood-pool agent. Preliminary experience.

RATIONALE AND OBJECTIVES: The author assess the enhancement characteristics over time of spontaneous breast tumors in dogs comparing gadopentetate dimeglumine with a new blood-pool agent (24-gadolinium [Gd]-DTPA-cascade polymer). METHODS: Eighteen dogs with spontaneous breast tumors (5 carcinomas, 4 adenomas, and 9 benign mixed-tissue tumors) underwent dynamic magnetic resonance imaging after intravenous injection of gadopentetate dimeglumine and the blood-pool agent. Signal intensity time curves were followed up to 30 minutes after injection of both agents in the same animal. A nonlinear fitting routine enabled calculation of the delivery and clearance half lives of the contrast agent kinetics in each tumor. RESULTS: For gadopentetate dimeglumine, a fast signal increase was found immediately after intravenous injection, with a subsequent signal decay in all tumors. No difference was observed between the enhancement kinetics of different tumor types after gadopentetate dimeglumine application. Similar kinetics were found in benign lesions after injection of the blood-pool agent. However, in carcinomas the blood-pool agent displayed a slower delivery, delayed peak enhancement, and slower tumor tissue clearance or even a signal plateau of more than 30 minutes. CONCLUSIONS: Dynamic magnetic resonance imaging of breast neoplasms using a blood-pool agent may help to better differentiate between benign and malignant lesions because it demonstrates the enlarged interstitial space and increased capillary permeability in carcinomas.

Dynamic contrast-enhanced MR imaging of the upper abdomen: enhancement properties of gadobutrol, gadolinium-DTPA-polylysine, and gadolinium-DTPA-cascade-polymer.

The enhancement properties of gadobutrol (40 and 80 mumol/kg body weight, 550 daltons), gadolinium-DTPA-polylysine (20 mumol/kg body weight, 53,000 daltons) and gadolinium-DTPA-cascade-polymer (20 mumol/kg body weight, < 30,000 Daltons) were investigated in abdominal MR imaging using a pig model (n = 24). Signal intensities before and after contrast media application were assessed using a fast single slice FLASH sequence. Measurements were made every 4 s within the first 116 s, every minute between 4 and 10 min and after 15, 20, 30, 40, 50, 60, 90, and 120 min after contrast media injection. Injection of gadobutrol resulted in typical signal intensity curves characterizing it as an extracellular agent similar to gadopentetate dimeglumine. Significant enhancement was found in all tissues except the trunk muscles when the lower dose was administered. Gadolinium-DTPA-polylysine injection resulted also in significant enhancement of the liver, the pancreas, and the renal cortex, but not of the trunk muscle, reflecting its blood pool properties known also from other macromolecular contrast agents. The signal intensity curves obtained after gadolinium-DTPA-cascade-polymer injection were similar to those obtained after polylysine injection, stressing the blood pool character of this new type of blood pool agent.

Gd-DTPA-cascade-polymer: potential blood pool contrast agent for MR imaging.

Gadolinium-DTPA (diethylenetriaminepentaacetic acid)-cascade-polymer, a potential new blood pool contrast agent for magnetic resonance (MR) imaging, was compared with a known blood pool agent, Gd-DTPA-polylysine, in an animal model. The relative signal intensities of liver, renal cortex, pancreas, and trunk muscle were assessed in 12 pigs between 4 seconds and 120 minutes after injection of a 20 mumol/kg dose of each contrast agent, by using a FLASH (fast low-angle shot) sequence. Except for muscle, all tissues showed visible enhancement after injection of either contrast agent. After injection of Gd-DTPA-polymer, enhancement patterns in the liver, renal cortex, and pancreas were similar to those seen after injection of Gd-DTPA-polylysine. No statistically significant differences in enhancement between the two contrast agents were found at any time point. The authors conclude that the contrast kinetics of Gd-DTPA-cascade-polymer are similar to those of Gd-DTPA-polylysine and that this agent may also be used as a blood pool contrast agent for MR imaging.