[The rubric "Picture of the month"].
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Breast Neoplasms↗
Biomedical subjects
T Lorentzen
Publications and source records attributed to T Lorentzen.
Extracranial arteriovenous malformation diagnosed on color Doppler imaging.
Arteriovenous (AV) malformations are rare and may occur at various locations, like in the brain, liver, lungs, or in the subcutaneous tissue. This case report describes an AV malformation from the right occipital artery. The value of combined B-mode ultrasonography and color Doppler mode imaging of masses in the neck region is discussed.
Female↗
Perioperative Doppler ultrasonography: renal detection of renal graft perfusion.
Irreversible damage of renal transplants may be prevented if insufficient graft perfusion can be detected perioperatively. Colour and spectral Doppler ultrasonography were performed in 30 consecutive renal transplants. The perfusion of the graft and the Resistive Index (RI) were evaluated perioperatively (perioperatively and less than 15 min postoperatively) and 24 h after the operation in all patients. In four cases (13.3%) RI > 0.9 was detected and immediate surgical correction of the cause led to a normalization (RI < 0.8) in all four cases. A RI < 0.9 required no intervention in 26 cases (86.7%). All renal grafts in this series were functioning 1 month postoperatively. In a comparative group, 30 consecutive transplants carried out at our institution without perioperative Doppler ultrasonography evaluation, a loss of four renal grafts perioperatively was recorded retrospectively. We conclude that perioperative ultrasonography Doppler evaluation may provide an easy applicable and reliable method for early detection of insufficient renal graft perfusion, allowing surgical correction before irreversible damage of the graft occurs. RI > 0.9 is pathological. A continuation of the study is required to clarify the long-term value of perioperative Doppler ultrasonography graft monitoring.
Adult↗
Applications of high-energy synchrotron radiation for structural studies of polycrystalline materials.
The large penetration power of high-energy X-rays (>60 keV) raises interesting prospects for new types of structural characterizations of polycrystalline materials. It becomes possible in a non-destructive manner to perform local studies, within the bulk of the material, of the fundamental materials physics properties: grain orientations, strain, dislocation densities etc. In favourable cases these properties may be mapped in three dimensions with a spatial resolution that matches the dimensions of the individual grains. Imbedded volumes and interfaces become accessible. Moreover, the high energies allow better in-situ studies of samples in complicated environments (industrial process optimization). General techniques for research in this energy range have been developed using broad-band angle-dispersive methods, on-line two-dimensional detectors and conical slits. Characterizations have been made at the level of the individual grains and grain boundaries as well as on ensembles of grains. The spatial resolution is presently of the order of 10-100 micom. Four examples of applications are presented along with an outlook.
Journal Article↗
Radiofrequency tissue ablation with a cooled needle in vitro: ultrasonography, dose response, and lesion temperature.
RATIONALE AND OBJECTIVES: Radiofrequency (RF) tissue ablation with a cooled needle electrode (probe) can produce large lesions. By using this technique on ex vivo calf livers, the authors evaluated the role of ultrasound (US), dose response, and temperature course with time. METHODS: RF ablation was produced with a 14-gauge probe with a 2-cm exposed tip. The lesions were examined with US and macroscopically after various treatment durations. Tissue temperature was measured with thermosensors inserted 1, 2, and 3 cm from the probe. RESULTS: Before treatment the tip of the probe was easy to visualize with US, but treatment microbubbles obscured the lesion and probe. After treatment, the lesions appeared hypoechoic. Lesion size was underestimated based on US findings. Lesion size was logarithmically correlated to treatment duration. Lesion temperature increased at an increased rate with higher wattage applied and with decreased distance from the probe. CONCLUSION: US is useful for probe placement before treatment and might be of value after treatment. Lesion size increases reproducibility with treatment duration.
Animals↗
[Phlegmasia alba dolens diagnosed with Doppler ultrasonography].
Differential diagnostic problems may occur in a patient with a cold, pale and swollen leg. Especially when the peripheral blood pressure is reduced, it is particularly difficult to distinguish cases caused by venous thrombosis from those caused by arterial embolism. Colour-Doppler ultra-sonography might be helpful for establishing the correct diagnosis. A case history is presented.
Aged↗
A cooled needle electrode for radiofrequency tissue ablation: thermodynamic aspects of improved performance compared with conventional needle design.
RATIONALE AND OBJECTIVES: I developed and tested a cooled needle electrode (CNE) for radiofrequency (RF) tissue ablation in vitro. METHODS: A 2-mm needle electrode with two lumina for internal water perfusion and irrigation of the needle tip and a conventional needle electrode were tested in ex vivo calf liver during different levels of output power (wattage). RF lesions produced by the two needle types were further evaluated with a thermal camera. RESULTS: When the CNE was used, a significant increase in the duration of ablation was observed, which caused a significant increase in delivered energy and lesion size when compared with the conventional needle electrode. The largest lesion produced with the CNE was almost spherical and measured 41 x 37 mm (longitudinal x transverse). The cooling effect was reflected in the image obtained with the thermal camera. CONCLUSION: This technique produced very large lesions compared with conventional methods and may have a role in many different kinds of RF needle ablation.
Animals↗
The loop electrode: in vitro evaluation of a device for ultrasound-guided interstitial tissue ablation using radiofrequency electrosurgery.
RATIONALE AND OBJECTIVES: I developed and tested in vitro a device for ultrasound-guided monopolar radiofrequency (RF) electrosurgical interstitial tissue ablation. METHODS: The current was applied to an electrode with a distal loop form (radius = 1 cm). The superelastic properties of the electrode allowed cannula introduction in the experimental medium (calf liver) before subsequent rotation of the electrosurgical cutting electrode, resulting in cutting off and isolation of a spherical lesion interstitially. The optimal setting of the RF unit and the optimal cutting speed were evaluated. Under ultrasonographic guidance and monitoring, approximately 150 lesions were produced with different loop designs and sizes. The gross appearance was evaluated and correlated to ultrasonography. RESULTS: An output effect of 200 W was optimal for resection and cutting with the loop electrode. An ellipsoid loop configuration could produce an almost spherical lesion with a diameter of 2.0 cm interstitially. Ultrasonography could guide the introduction of the loop electrode into tissue and visualize the upper part of the lesion. CONCLUSION: The loop electrode is a technique for percutaneous ultrasonographically guided tissue ablation. It was proved to be efficient in vitro by producing 2-cm liver lesions.
Animals↗
Prostatectomy and impotence: can temperature variations around the prostate during TURP explain postprostatectomy impotence?
A considerable number of patients (4-35%) experience sexual dysfunction after treatment for BPH with a transurethral resection of the prostate (TURP). The aim of this study was to elucidate whether heat, generated by the resectoscope during TUR-P, can be transmitted to the surrounding tissue to an extent that may damage the penile innervation.
Aged↗
[Ultrasonic angiography: principles and clinical use].
A new technique for detecting blood flow called Colour Doppler Energy (CDE), Power Doppler or Ultrasound Angio, is based on the integrated power spectrum of the standard Doppler signal used for Colour Flow Mapping (CFM). CDE is independent of the insonation angle, has no aliasing artefacts and improves the sensitivity with respect to detection of the presence or absence of flow compared to CFM. However, CDE provides no directional or quantitative information about the flow. CDE is superior to CFM in detection of low velocity flow, perfusion in small vessels, flow in torsioned vessels and flow in multiple vessels in the same image plane. The clinical applications are reviewed. Complicated stenosis, renal perfusion, penile Doppler and scanning of the vessels of the extremities are examples where CDE improves sensitivity in detecting flow compared to CFM.
Angiography↗
Ultrasonically guided insertion of a peritoneo-gastric shunt in patients with malignant ascites.
PURPOSE: A new method for internal drainage of malignant ascites is presented in 5 patients with symptomatic malignant ascites. MATERIAL AND METHODS: US-guided percutaneous gastrostomy and paracentesis were performed using the Seldinger technique. A 2.5-mm Cope-loop catheter was inserted in the fluid-filled stomach. In the lower abdomen the proximal part of a Denver peritoneo-venous shunt was introduced after dilation up to 4.8 mm. The pump chamber was sutured to the skin. The distal part of the Denver shunt was cut a few cm from the pump chamber and connected to the gastrostomy catheter. When pumping, ascites is shunted to the stomach lumen. RESULTS: The insertion presented no complications, and all shunt systems initially functioned well. However, the shunts had to be removed within the first 2 weeks because of mechanical problems such as clotting, leakage, and peritoneal septum formation. No infections were reported. CONCLUSION: The peritoneo-gastric shunt may present a therapeutic alternative in selected patients, but the mechanical problems have first to be solved.
Anastomosis, Surgical↗
Percutaneous gastrostomy guided by ultrasound and fluoroscopy.
Percutaneous gastrostomy, utilizing a dedicated catheterization kit, with a combination of ultrasonographic (US) and fluoroscopic guidance, was carried out in 27 patients. The main indication for gastrostomy was the need for nutritional support in malignant esophageal stricture. After distending the stomach with water via a nasogastric tube, the gastric antrum was punctured under US guidance and a guide wire was inserted, followed by fluoroscopically guided tract dilatation and insertion of a 2.5-mm Cope-loop catheter. In all patients but one (96%) the procedure was successfully completed in one or 2 attempts. Two complications occurred: one case of a small subcutaneous abscess near the puncture site, and one late incident of dislodgement of a catheter without string-loop fixation, which had been inserted at a catheter exchange after 6 weeks. Percutaneous gastrostomy guided by US and fluoroscopy is a safe and efficacious alternative to endoscopic and surgical gastrostomy.
Adult↗
[Functional treatment of surgically treated empyema of the knee joint].
Knee-joint empyema requires prompt surgical management. After debridement the joint needs to be irrigated for several days. Functional follow-up treatment with electromotive splints according to the CPM concept should begin soon after surgery. Follow-up examination of patients treated in this way for knee-joint empyema showed a protracted course with worse results for empyemas subsequent to arthrotomy, while joint infections after less severe injuries (skin lesions, puncture) healed successfully.
Adolescent↗
Prevalence of Helicobacter pylori in gastrointestinal disorders and concentrations of ciprofloxacin in serum and gastric mucosa.
Endoscopic antral biopsies were obtained from 30 patients with several gastrointestinal disorders and analysed for the presence of H. pylori. This bacterium was present in 80% and 58%, respectively, of patients with either gastric and duodenal ulcers and gastric neoplasm. In none of the healthy individuals, H. pylori could be found. Another 14 patients with various diseases of the stomach, undergoing a major gastric resection, had been treated with 200 mg ciprofloxacin intravenously immediately before the operation. Blood and various tissues samples were taken during the operation. The prevalence of IgG antibodies against H. pylori in these patients was 93%. H. pylori could be determined in 71% of the cases by the urease production; by culture, this was possible in only one case. The mean peak concentration of ciprofloxacin in serum was 5.31 mg/l and 1.17 mg/l, respectively, immediately and 60 min after the end of infusion; in tissues of antrum and duodenum, 1.59 to 1.64 mg/kg and 1.41 to 1.72 mg/kg, respectively, 45-270 min after the infusion. The results show that ciprofloxacin rapidly penetrates into tissues and attains concentrations greater than the MIC90 for H. pylori. However, these concentrations can inhibit the isolation of this microorganism but not its urease activity. This fact could be interpreted by the existence of a nonculturable but metabolically active form of H. pylori. This would explain the high rate of recrudescence following most types of currently applied therapeutic schemes.
Adult↗
Interstitial hyperthermia of colorectal liver metastases with a US-guided Nd-YAG laser with a diffuser tip: a pilot clinical study.
Ultrasound (US)-guided interstitial hyperthermia performed with the neodymium yttrium aluminum garnet laser with a diffuser tip involves placement of a laser fiber in solid tissue followed by irradiation from within the center of the tumor to be treated. The authors previously described the development of a US-guided technique that permits simultaneous interstitial laser irradiation and temperature measurements, with real-time US monitoring. With the use of a dedicated diffuser tip modification of the bare laser fiber, it has proved possible to produce spherical coagulations with a diameter comparable to that of liver metastases of clinical relevance. This technique was used in 11 patients with 16 colorectal liver metastases, 12 of which were radically ablated. Real-time US and interstitial temperature monitoring during treatment had a positive predictive value of 86% and negative predictive value of 100% in judging the final result. The technique is feasible, effective, and safe, but the effect on patient survival must be tested in future randomized clinical studies.
Adult↗
Secretin and portal blood flow.
Using a duplex Doppler technique, we investigated the effect of low doses of secretin on the portal blood flow. In eight healthy volunteers successive intravenous secretin infusions of 0, 8, and 32 pmol x kg-1 x h-1 resulted in proportional increases in plasma secretin levels. The portal venous flow, however, was unaffected. A bolus injection of 930 pmol of secretin caused plasma secretin levels to increase 100-fold, whereas blood flow in the portal vein increased only by a factor three. This suggests that secretin in the present dose range is of no quantitative importance as a regulator of portal venous flow under physiologic conditions.
Adult↗
Gastric and duodenal wall thickening on abdominal ultrasonography. Positive predictive value.
In a retrospective study, 79 patients with gastric (n = 59) or duodenal (n = 20) wall thickening on conventional abdominal ultrasonograms were included. To reduce bias, patients with a microscopic diagnosis of upper GI neoplasia present at the time of scanning were excluded. The final diagnosis was based upon endoscopy, operation, upper GI series, or autopsy. Among the 59 cases of gastric wall thickening, 33 (56%) proved to be gastric cancer, one (2%) was benign neoplasia, and 17 (29%) showed nonneoplastic pathology (ulcer, gastritis, fibrosis). In eight cases (13%) no gastric pathology was present in the final diagnosis, thus producing false-positive sonographic diagnoses. Among the 20 cases of duodenal wall thickening, five (25%) proved to be duodenal cancer and seven (35%) showed nonneoplastic duodenal pathology. We concluded that gastric or duodenal wall thickening shown on abdominal sonography is a significant finding indicating upper GI pathology (malignant or nonmalignant) in a high percentage of the gastric (86%) and duodenal (60%) cases.
Adult↗
Local staging of prostate cancer with transrectal ultrasound: a literature review.
A literature review was undertaken to investigate whether transrectal ultrasound can predict the local stage of prostate cancer. Twelve papers were found which correlated ultrasound findings with surgical findings and another paper reported on strategic staging biopsies guided by transrectal ultrasound. Eleven of these papers reported on ultrasound findings in patients in whom digital rectal examination had defined localized disease. One paper compared ultrasound findings and digital rectal findings. One paper indicated that transrectal ultrasound, though not suited to patients with clinically localized disease defined by digital rectal examination, may be superior as the initial staging tool. We conclude that transrectal ultrasound has too low a specificity to upgrade the diagnostic results of digital rectal examination, but that it may be more useful as the primary staging tool and for guidance in strategic staging biopsies.
Humans↗