Three-dimensional rotational angiography (3D-RA) is an established method within the field of interventional neuroradiology. The method has also a great potential in other areas with a complicated arterial anatomy. The purpose of this study was firstly to develop an investigative protocol for 3D-RA in renal transplanted patients with threatening allograft failure in diagnosing stenosis in the transplanted renal artery; secondly the protocol was evaluated and compared with a modified protocol including reduced contrast medium load. Furthermore, the advantages of the 3D reconstructions compared to the angiographic images were evaluated, likewise if an extended angle of rotation reduced the artifacts in the 3D reconstructions. The two protocols were compared with regard to image quality and acute nephrotoxicity. The accuracy of Doppler ultrasonography and the result of percutaneous transluminal angioplasty (PTA) were also assessed. 3D-RA was consecutively performed in 57 renal transplanted patients with suspicion of renal artery stenosis. A significant stenosis was found in 49% of the patients. The 3D reconstructions profiled 43% of the transplant renal artery stenoses better than the angiographic images. An extended angle of rotation reduced the artifacts. There was no statistical difference regarding image quality between the two protocols, and the renal function was equally affected in both protocols. Doppler ultrasonography sensitivity was 100%; specificity was 48% and positive predictive value 67%. PTA had a technical success rate of 92% and a clinical success rate of 75% after 3 months. 3D-RA is a helpful supplement in cases with complicated vascular anatomy, especially when PTA may be indicated. The 3D reconstructions profile the course of the artery more frequently than the angiographic images and support PTA. The 3D reconstructions are degraded of artifacts. Sampling artifacts can be diminished by increased C-arm rotation and increased number of projections. The distortions caused by beam hardening remain to be solved.

Renal artery stenosis (RAS) is a potentially curable cause of hypertension and azotemia. Besides intra-arterial renal angiography there are several non-invasive techniques utilized to diagnose patients with suspicion of renal artery stenosis. Removing the stenosis by revascularization to restore unobstructed blood flow to the kidney is known to improve and even cure hypertension/azotemia, but is associated with a significant complication rate. To visualize renal arteries with x-ray techniques a contrast medium must be used. In a randomized, prospective study the complications of two types of contrast media (CO2 and ioxaglate) were compared. CO2 was not associated with acute nephropathy, but induced nausea and had lower attenuation differences compared to Ioxaglate. Acute nephropathy was related to the ioxaglate dose and the risk was evident even at very low doses if the patients were azotemic with creatinine clearance <40 ml/min. Evaluating patients for clinically relevant renal artery stenosis can be done utilizing several non-invasive techniques. MRA was retrospectively evaluated and shown to be accurate in detecting hemodynamically significant RAS. In a prospective study of 58 patients, evaluated with four methods for renal artery stenosis, it was shown that MRA and CTA were significantly better than ultrasonography and captopril renography in detecting hemodynamically significant RAS. The standard of reference was trans-stenotic pressure gradient measurement, defining a stenosis as significant at a gradient of ≥15 mmHg. The discrepancies were mainly found in the presence of borderline stenosis. The outcome of percutaneous revascularization procedures showed a technical success rate of 95%, clinical benefit in 63% of treated patients, 30-day mortality 1.5% and major complication rate of 13%. The major complication rate for patients with baseline serum creatinine >300µmol/l was 32%. Our results compare favorably with published studies and guidelines.

<p>The aims of this work were to image and analyze the needle behavior at automated core biopsy, to investigate the clinical utility of an alternative core biopsy technique using a semiautomated gun in breast and axillary lesions, and also to compare core biopsy with surgical specimens in malignant breast lesions regarding histologic features and hormone receptor expression.</p><p>In two experimental studies, using butter and silicon phantoms, respectively, the needle pass was imaged and its dynamic behavior studied. It was shown that the needle took a curved course in phantoms. It deviated to the same side as where the tip lay, and the degree of the curvature increased with increasing hardness of the phantoms. Our experimental methods can be applied for imaging of needle behavior and thereby improvement of needle configuration.</p><p>In two clinical studies, a semiautomated gun was used for large needle core biopsy of breast and axillary lesions in two series of 145 and 21 patients, respectively. The sensitivity of the method for diagnosis of malignancy was 87% (108/124), and in 37% (31/83) of cases the full length of the needle notch was filled with specimen. No injury to the neurovascular structures of the axillary area was observed. It was concluded that the semiautomated gun can be used as an alternative to the automated gun when the size and location of the lesion render use of the automatic device uncertain or dangerous, e.g., in small breast lesions or lesions located in the axilla.</p><p>In a series of 129 cases of breast cancer, comparison of core biopsy and surgical specimens showed that core biopsy provided enough information on the histologic type and grade of the lesions. Also, there was moderate to high concordance between the two methods for assessment of progesterone receptors and estrogen receptors (Spearman`s kappa 0.67 and 0.89, respectively).</p>

The aims of this work were to image and analyze the needle behavior at automated core biopsy, to investigate the clinical utility of an alternative core biopsy technique using a semiautomated gun in breast and axillary lesions, and also to compare core biopsy with surgical specimens in malignant breast lesions regarding histologic features and hormone receptor expression. In two experimental studies, using butter and silicon phantoms, respectively, the needle pass was imaged and its dynamic behavior studied. It was shown that the needle took a curved course in phantoms. It deviated to the same side as where the tip lay, and the degree of the curvature increased with increasing hardness of the phantoms. Our experimental methods can be applied for imaging of needle behavior and thereby improvement of needle configuration. In two clinical studies, a semiautomated gun was used for large needle core biopsy of breast and axillary lesions in two series of 145 and 21 patients, respectively. The sensitivity of the method for diagnosis of malignancy was 87% (108/124), and in 37% (31/83) of cases the full length of the needle notch was filled with specimen. No injury to the neurovascular structures of the axillary area was observed. It was concluded that the semiautomated gun can be used as an alternative to the automated gun when the size and location of the lesion render use of the automatic device uncertain or dangerous, e.g., in small breast lesions or lesions located in the axilla. In a series of 129 cases of breast cancer, comparison of core biopsy and surgical specimens showed that core biopsy provided enough information on the histologic type and grade of the lesions. Also, there was moderate to high concordance between the two methods for assessment of progesterone receptors and estrogen receptors (Spearman`s kappa 0.67 and 0.89, respectively).

<p>Bakgrund: Tidigare forskning visar att röntgensjuksköterskor som gör patienterna delaktiga genom att tillhandahålla information gör det möjligt för patienterna att förstå och själv ta aktiv roll i sin undersökning vilket leder till mindre oro. Med kunskaper och erfarenheter kunde röntgensjuksköterskorna stödja patienterna i samband med undersökningen vilket skapade förtroende och säkerställde trygg atmosfär. Dock kunde sjuksköterskorna även visa brist på känslomässigt engagemang samt bristande förmåga att kommunicera när de var upptagen med praktiska arbetsuppgifter.</p><p>Syfte: Syftet med studien var att beskriva patientens upplevelse av det korta mötet inom vården, med tanken att finna överförbarhet till möte med en röntgensjuksköterska.</p><p>Metod: Litteraturstudie med en kvalitativ ansats och med en kvalitativ innehållsanalys. Studien inkluderade tio vetenskapliga artiklar, som beskriver möten med vården på röntgen, akut- och operationsavdelning.</p><p>Resultat: Resultatet speglar patienternas upplevelser av korta möten, med tonvikten lagd på möten med röntgensjuksköterskor. I resultatet kan referens till källmaterial och dess kontext, såsom röntgen-, akut- och operationsavdelning, utläsas. Dataanalysen resulterade tre huvudkategorier: <em>att bli bekräftad</em>, <em>att uppleva</em> <em>trygghet</em> och <em>att känna</em> <em>maktlöshet</em>. I kategorierna finns totalt sju subkategorier inkluderade. Patienterna kände sig respekterade och bekräftade som individer när sjuksköterskan lyssnade på dem samt tog deras klagomål och önskemål på allvar. Patienterna upplevde trygghet när sjuksköterskan uttryckte intresse och gav dem relevant information. Patienterna upplevde däremot maktlöshet när det var svårt att få kontakt med sjuksköterskan samt göra sina åsikter hörda.</p><p>Slutsats: Studiens resultat visar att patienternas upplevelser av korta möten med röntgensjuksköterskor är allmängiltiga i den bemärkelsen att de kan sägas gälla för verksamheter såsom röntgen-, akut- och operationsavdelning. Dock är det viktigt att poängtera att varje möte med en patient är unikt, vilket innebär att varje patient ska bemötas på ett sätt som skapar förutsättningar för ett välbefinnande.</p>

Radio-Frequency (RF) lesioning, or RF ablation, is a method that uses high frequency currents for thermal coagulation of pathological tissue or signal pathways. The current is delivered from an electrode, which also contains a temperature sensor permitting control of the current at a desired target temperature. In the brain, RF lesioning can e.g. be used for treatment of severe chronic pain and movement disorders such as Parkinson’s disease. This thesis focuses on modelling and simulation with the aim of gaining better understanding and predictability of the lesioning process in the central brain.   The finite element method (FEM), together with experimental comparisons, was used to study the effects of electric and thermal conductivity, blood perfusion (Paper I), and cerebrospinal fluid (CSF) filled cysts (Paper II) on resulting lesion volume and shape in brain tissue. The influence of blood perfusion was modelled as an increase in thermal conductivity in non-coagulated tissue. This model gave smaller simulated lesions with increasing blood perfusion as heat was more efficiently conducted from the rim of the lesion. If the coagulation was not taken into consideration, the lesion became larger with increasing thermal conductivity instead, as the increase in conducted heat was compensated for through an increased power output in order to maintain the target temperature. Simulated lesions corresponded well to experimental in-vivo lesions. The electric conductivity in a homogeneous surrounding had little impact but this was not true for a heterogeneous surrounding. CSF has a much higher electric conductivity than brain tissue, which focused the current to the cyst if the electrode tip was in contact with both a cyst and brain tissue. Heating of CSF could also cause considerable convective flow and as a result a very efficient heat transfer. This affected both simulated and experimental lesion sizes and shapes. As a result both very large and very small lesions could be obtained depending on whether sufficient power was supplied or if the heating was mitigated over a large volume.   Clinical (Paper IV) and experimental (Paper III) measurements were used for investigation of changes in reflected light intensity from undamaged and coagulating brain tissue respectively. Monte Carlo (MC) simulations for light transport were made for comparison (Paper V). For the optical measurements, an RF electrode with adjacent optical fibres was used and this electrode was also modelled for the optical simulations. According to the MC simulations, coagulation should make grey matter lighter and white matter darker, while thalamic light grey should remain approximately the same. Experiments in ex-vivo porcine tissue gave an increase in reflected light intensity from grey matter at approximately 50 °C but the signal was very variable and the isotherm 60 °C gave better agreement between simulated and experimental lesions. No consistent decrease in reflected light intensity could be seen during coagulation of white matter. Clinical measurements were performed during the creation of 21 trajectories for deep brain stimulation electrodes. In agreement with the simulations, reflected light intensity was found to differentiate well between undamaged grey, light grey and white matter.   In conclusion, blood perfusion and CSF in particular may greatly affect the lesioning process and can be important to consider when planning surgery. Reflected light intensity seems unreliable for the detection of coagulation in light grey brain matter such as the thalamus. However, it seems very promising for navigation in the brain and for detection of coagulation in other tissue types such as muscle.

<p>Solid organ transplantation is today an established form of treatment for end-stage organ disease. Monitoring of graft function and pharmacological therapy constitutes a maze of clinical observations and histological evaluations of biopsy specimens; with the biopsy results playing a decisive role. The aims of this doctoral research were to investigate the feasibility of detecting acute rejection of transplanted organs and monitoring the effect of anti-rejection treatment, with the use of ultrasmall superparamagnetic iron oxide particles (USPIO) and magnetic resonance (MR) imaging with a clinical MR scanner.</p><p>Allogeneic and syngeneic heterotopic heart transplantations were performed in rats. Three different-sized USPIO were given to one allogeneic and one syngeneic group. The change in MR signal intensity (SI) over time was measured. An increase in SI was interpreted as damage to micro vessels due to the pronounced inflammatory reaction caused by acute rejection, which led to leakage of USPIO into the tissue. A decrease in SI was interpreted as normal vascular structure, since USPIO normally remains in the intravascular space. The same method, using one of the previously tested USPIO, was used in a treatment study in which acute rejection in transplanted rats was induced and subsequently treated. An attempt was also made to detect presence of macrophages in an acutely rejecting graft, since this cell type plays an important role in the acute rejection process; this was done by testing the ability of macrophages to phagocytose the UPSIO compound.</p><p>In permeability studies with MR imaging all three USPIO tested discriminated between rejecting and non-rejecting grafts without any overlap of the groups. Factors that contributed to the ability to distinguish between grafts were the size and half-life of the particle. We were also able to monitor effects of anti-rejection treatment by studying the vascular permeability of USPIO and MR imaging. We did not succeed in detecting macrophages in the rejecting grafts with USPIO and MR imaging.</p><p>This thesis presents a novel approach to detection of acute rejection of transplanted organs and to monitoring the effects of anti-rejection treatment using different USPIO contrast agents and MR imaging in a clinical MR scanner.</p>

<p>Myocardial infarction (MI) causes high morbidity and mortality worldwide and for effective prevention and treatment MIs have to be adequately detected. </p><p>The existence of clinically unrecognized MIs (UMIs) has been known for the past hundred years, but an ultimate tool for their detection has not yet been found. Using persistent Q waves on electrocardiography as a sign of MI, it has been estimated that UMIs constitute at least ¼ of all MIs and have mortality rates similar to those of recognized MIs (RMIs). These estimates are misleading, however, since persistent Q waves do not necessarily represent MIs.</p><p>The late enhancement technique in magnetic resonance imaging (LE MRI) has been developed over the past decade and accurately determines myocardial viability. The aim of this research was to investigate the prevalence and impact of UMI and RMI in a population-based sample of 70-year-olds, assessed with MRI.</p><p>Cardiac function and viability were examined with MRI in 259 randomly selected 70-year-old subjects (127 women, 132 men) participating in a larger population-based study (PIVUS). Information on other parameters of cardiovascular disease was obtained and related to the findings.</p><p>Three methods for segmentation of the left ventricular mass were used in the first 100 subjects; these differed in accuracy and led to differences in systolic function values. In the subsequent 159 examinations one of the segmentation methods was used. </p><p>The viability images were assessable in 248 subjects (123 women, 125 men). Among these, the prevalence of UMI, 19.8%, definitely exceeded the expectations and UMIs constituted 4/5 of all MIs. The prevalence of RMI was 4.4%. MRI-detected UMIs differed from RMIs in several respects; they were smaller, frequently located inferolaterally, did not appear to be associated with atherosclerosis, and displayed increased collagen turnover. The pathogenesis of these UMIs remains to be investigated, but our observations suggest that they are caused by ischemia. Subjects with UMI showed increased cardiac morbidity, a decreased ejection fraction and an increased left ventricular mass, indicating an increased cardiovascular risk.</p><p>It is thus important to detect these UMIs, and this is adequately achieved by LE MRI. However, to decide upon prevention and treatment of these UMIs we need to know more about their pathogenesis and prognosis.</p>

Solid organ transplantation is today an established form of treatment for end-stage organ disease. Monitoring of graft function and pharmacological therapy constitutes a maze of clinical observations and histological evaluations of biopsy specimens; with the biopsy results playing a decisive role. The aims of this doctoral research were to investigate the feasibility of detecting acute rejection of transplanted organs and monitoring the effect of anti-rejection treatment, with the use of ultrasmall superparamagnetic iron oxide particles (USPIO) and magnetic resonance (MR) imaging with a clinical MR scanner. Allogeneic and syngeneic heterotopic heart transplantations were performed in rats. Three different-sized USPIO were given to one allogeneic and one syngeneic group. The change in MR signal intensity (SI) over time was measured. An increase in SI was interpreted as damage to micro vessels due to the pronounced inflammatory reaction caused by acute rejection, which led to leakage of USPIO into the tissue. A decrease in SI was interpreted as normal vascular structure, since USPIO normally remains in the intravascular space. The same method, using one of the previously tested USPIO, was used in a treatment study in which acute rejection in transplanted rats was induced and subsequently treated. An attempt was also made to detect presence of macrophages in an acutely rejecting graft, since this cell type plays an important role in the acute rejection process; this was done by testing the ability of macrophages to phagocytose the UPSIO compound. In permeability studies with MR imaging all three USPIO tested discriminated between rejecting and non-rejecting grafts without any overlap of the groups. Factors that contributed to the ability to distinguish between grafts were the size and half-life of the particle. We were also able to monitor effects of anti-rejection treatment by studying the vascular permeability of USPIO and MR imaging. We did not succeed in detecting macrophages in the rejecting grafts with USPIO and MR imaging. This thesis presents a novel approach to detection of acute rejection of transplanted organs and to monitoring the effects of anti-rejection treatment using different USPIO contrast agents and MR imaging in a clinical MR scanner.

Myocardial infarction (MI) causes high morbidity and mortality worldwide and for effective prevention and treatment MIs have to be adequately detected. The existence of clinically unrecognized MIs (UMIs) has been known for the past hundred years, but an ultimate tool for their detection has not yet been found. Using persistent Q waves on electrocardiography as a sign of MI, it has been estimated that UMIs constitute at least ¼ of all MIs and have mortality rates similar to those of recognized MIs (RMIs). These estimates are misleading, however, since persistent Q waves do not necessarily represent MIs. The late enhancement technique in magnetic resonance imaging (LE MRI) has been developed over the past decade and accurately determines myocardial viability. The aim of this research was to investigate the prevalence and impact of UMI and RMI in a population-based sample of 70-year-olds, assessed with MRI. Cardiac function and viability were examined with MRI in 259 randomly selected 70-year-old subjects (127 women, 132 men) participating in a larger population-based study (PIVUS). Information on other parameters of cardiovascular disease was obtained and related to the findings. Three methods for segmentation of the left ventricular mass were used in the first 100 subjects; these differed in accuracy and led to differences in systolic function values. In the subsequent 159 examinations one of the segmentation methods was used. The viability images were assessable in 248 subjects (123 women, 125 men). Among these, the prevalence of UMI, 19.8%, definitely exceeded the expectations and UMIs constituted 4/5 of all MIs. The prevalence of RMI was 4.4%. MRI-detected UMIs differed from RMIs in several respects; they were smaller, frequently located inferolaterally, did not appear to be associated with atherosclerosis, and displayed increased collagen turnover. The pathogenesis of these UMIs remains to be investigated, but our observations suggest that they are caused by ischemia. Subjects with UMI showed increased cardiac morbidity, a decreased ejection fraction and an increased left ventricular mass, indicating an increased cardiovascular risk. It is thus important to detect these UMIs, and this is adequately achieved by LE MRI. However, to decide upon prevention and treatment of these UMIs we need to know more about their pathogenesis and prognosis.