A virtual environment for surgical image guidance in intraoperative MRI.

Intraoperative MRI has recently entered the operating room as a new imaging modality. Customized visualization systems might further facilitate the use of this imaging technology. A visualization system for use in the interventional MRI has been developed, providing a virtual environment for surgical navigation using real-time images and for controlling the scanner. The visualization system has customized features for certain clinical applications. A training and testing facility has also been established. The introduction of the visualization system in the interventional MRI overcame several ambiguities and inconsistencies that were previously present, and resulted in a more transparent man-machine interface approach. A pilot study using the software to place cryoprobes in an animal liver showed promising results. Augmentation of real-time MR images with 3D rendering and customized navigation features opens new possibilities in intraoperative MRI. The described system can also be extended to other intraoperative imaging modalities.     

Image-guided stereotaxy in the interventional MRI.

BACKGROUND: Stereotactic procedures employing frame-based systems and utilizing pre-operative MR or CT have several shortcomings such as long procedure time, patient discomfort and transport, poor fail-safe capabilities and targeting inaccuracies due to brain shift. Conducting all procedural steps in an interventional MRI has the potential of alleviating some of these deficiencies. METHODS: A stereotactic system consisting of a skull-mounted mechanical positioning device and customized navigation software has been developed. The accuracy of this system was tested within an interventional MRI employing a skull phantom. RESULTS: The mean distance between the targets hit and the planned target coordinates was 0.70 mm +/- 0.3 mm with a maximum distance of 1.3 mm. INTERPRETATION: The results indicate that the proposed stereotactic system can be used for stereotactic procedures in the interventional MRI.     

Real time MRI-guided excision and cryo-treatment of osteoid osteoma in os ischii--a case report

Arterial embolisation with radio-active microspheres was used to measure the proportion of cardiac output to the skeleton and the tibiofibular bone both in unoperated rabbits and in rabbits after tibial osteotomy and subsequent external fixation. The mean uptake of the intact tibiofibula was 0.11 per cent of the cardiac output and, correspondingly, 0.21 per cent after the osteotomy. Maximal uptake occurred 18 days after the operation which was accompanied by a slight decrease in overall skeletal circulation.     

Reasons for treating secondary AML as de novo AML

In a Danish bi‐regional registry‐based study, we conducted an analysis of the incidence and clinical importance of secondary acute myeloid leukaemia (AML). In a total of 630 cases of AML, we found 157 (25%) cases of secondary AML. The secondary leukaemia arose from MDS (myelodysplastic syndrome) in 77 cases (49%), CMPD (chronic myeloproliferative disorder) in 43 cases (27%) and was therapy‐related AML (t‐AML) in 37 cases (24%). Median age at diagnosis of AML was 69 yr in secondary cases when compared to 66 yr in de novo cases (P = 0.006). In univariate analyses, secondary AML was associated with an inferior complete remission (CR) rate (P = 0.008) and poorer overall survival (OS, P = 0.003) whereas in complete remitters, disease‐free survival (DFS) of secondary cases was equal to that of de novo cases. Interestingly, in all further analyses of CR‐rates, OS and DFS, when correcting for the influence of age, cytogenetic abnormalities, performance status and leucocyte count (WBC), presence of secondary AML completely lost prognostic significance. We conclude that the presence of secondary AML does not per se convey an unfavourable prognosis and that patients with secondary AML should be offered the chance of benefiting from treatment according to current frontline AML protocols.     

High screening blood pressure is related to sympathetic nervous system activity and insulin resistance in healthy young men

The cardiovascular metabolic syndrome is characterized by the presence of several cardiovascular risk factors, including blood pressure (BP) elevation. We aimed to study the relation between mental stress, plasma catecholamines, BP and BP responses to mental stress in healthy young Caucasian men selected from different levels of screening BP. We included 98 men with high and 22 men with normal screening BP. They were examined at baseline in the laboratory, during a hyperinsulinemic, isoglycemic glucose clamp and during mental stress. At baseline in the laboratory, the men with high screening BP were characterized by elevated BP (p < 0.005) and plasma catecholamines (p < 0.05), but unaltered serum lipid levels compared to men with normal screening BP. After 2 h rest the differences almost disappeared, but could be reproduced during a mental arithmetic stress test. The men with elevated screening BP had significantly higher fasting glucose (p = 0.01) and lower insulin sensitivity (p < 0.005). In a multiple regression model, norepinephrine during mental stress (R2 = 0.10, p < 0.05) was the main variable to retrospectively explain allocation to the normal or high screening BP group. In conclusion, young healthy men with elevated screening BP are characterized by increased sympathetic activity and insulin resistance. Norepinephrine during mental stress is the main variable to explain allocation to the normal or elevated screening BP group. We have shown that one single screening BP measurement predicts insulin resistance and elevated fasting glucose in this cohort.     

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Temperature measurement in soft tissue using a distributed fibre Bragg-grating sensor system

Currently used temperature sensor systems do not provide sufficient spatial resolution and can not be used as an integrated part of minimally invasive treatment. Few magnetic resonance (MR) compatible sensor systems are available. A distributed fibre Bragg-grating sensor system for use in biological tissue was constructed. Ten Bragg gratings were inscribed in the core of an optical fibre. The fibre was mounted into tubes made of MR-compatible materials. An opto-electronic unit connected to the fibre was used for signal generation and detection. Communication with a PC allowed presentation and logging of temperature data. The system was calibrated to the temperature range ‘195.8°C to 100°C. Experiments were conducted during freezing (cryoablation) of porcine liver in vivo. The system yielded a temperature profile with 6.5 mm spatial resolution and 5 s temporal resolution. Both mechanical stability and MR compatibility were acceptable and will allow routine use.     

Early recognition of regional cardiac ischemia using a 3-axis accelerometer sensor

Perioperative mortality in coronary artery bypass grafting is usually caused by reduced left ventricular function due to regional myocardial ischemia or infarction. Post-operative graft occlusion is a well-known problem in coronary surgery. A sensitive tool to detect graft occlusion and monitor myocardial function may give the opportunity to revise malfunctioning grafts before departure from the hospital. This paper describes how a new method can detect cardiac ischemia using a 3-axis piezoelectric accelerometer. In three anesthetized pigs, a 3-axis piezoelectric accelerometer was sutured on the lateral free wall of the left ventricle. The left anterior descending (LAD) was occluded for different time periods and the accelerometer data were sampled with a PC. Short-time Fourier transform was calculated based on the accelerometer time series. The results were visualized using a 2D color-coded time-frequency plot. In the area of occlusion, a change to stronger power of higher harmonics was observed. Consequently, a difference value between the instant frequency pattern and a reference frequency pattern showed a rise in absolute value during the occlusion period. The preliminary results indicate that early recognition of regional cardiac ischemia is possible by analyzing accelerometer data acquired from the three animal trials using the prototype 3-axis accelerometer sensor.     

Nonfunctioning pituitary adenoma: incidence,causes of death and quality of life in relation to pituitary function

The incidence of clinically significant, nonfunctioning pituitary adenoma, requiring surgical treatment, has not been established. According to previous studies, both surgery type and subsequent radiotherapy may have an impact on quality of life (QOL), and some studies have shown increased cardiovascular mortality in patients with pituitary disease. We studied all patients with functionless, suprasellar pituitary adenoma who were operated on during the period 1985–1996 (N = 192; transsphenoidal surgery = 160, craniotomy = 32). QOL was evaluated from Short Form 36 and Major Depression Inventory questionnaires. Causes of death were obtained from the Danish Register of Causes of Death. Incidence was 5.6/mill/year. Postoperatively, 27% of the patients had normal pituitary function and 27% were panhypopituitary. Fifty three patients had died. Death from cardiovascular, cerebrovascular and malignant diseases was not increased. Overall, QOL was not different from QOL of an age- and sex matched background population. QOL was, however, impaired in patients who had undergone craniotomy as compared to patients undergoing transsphenoidal surgery. QOL was not reduced in hypopituitary patients or in patients receiving radiotherapy. The study was supported by grants from The Aarhus University Hospital Research Initiative and The Obel Family Foundation, Aalborg, Denmark     

Real-time quantitative PCR of microdissected paraffin-embedded breast carcinoma: an alternative method for HER-2/neu analysis

We studied the feasibility of using real-time quantitative PCR to determine HER-2 DNA amplification and mRNA expression in microdissected formalin-fixed, paraffin-embedded breast tumors and compared this with standard immunohistochemistry (IHC) and fluorescent in situ hybridization (FISH) methods. Study cases (27 carcinomas and 3 ductal breast carcinoma in situ (DCIS) cases) showed varying Her-2 expression as determined by IHC (HercepTest). In carcinomas, there was a good correlation between HER-2 DNA amplification and strong HER-2 protein expression detected by FISH and IHC, respectively. A single DCIS case was amplified in FISH, but not in IHC. Both HER-2 gene amplification and expression could be quantified in microdissected paraffin-embedded tumors using real-time PCR, DNA and RNA being successfully detected in 146 of 150 (97%) and 141 of 150 (94%) samples, respectively. PCR analysis for HER-2 DNA amplification using the LightCycler HER2/neu DNA Quantification kit (Roche Molecular Biochemicals, Mannheim, Germany) correlated fairly well with IHC and FISH. All IHC HER-2 3+ tumors were amplified according to the kit, as was the FISH-amplified DCIS case. DNA-PCR identified five additional tumors as being amplified. Interestingly, all these scored 2+ with the HercepTest, but were negative using FISH. We believe that real-time quantitative PCR analysis of HER-2 DNA amplification following microdissection represents a useful supplementary or perhaps even an alternative technique for establishing HER-2 status in paraffin-embedded tumors.