Kristina Rue Nielsen

Biopsy Guided by Real-Time Sonography Fused with MRI : A Phantom Study

OBJECTIVE The purpose of our study was to test the accuracy of sonographically guided biopsies in a phantom of structures not visible on sonography but shown on MRI by using commercially available sonography systems with image fusion software. MATERIALS AND METHODS A previously recorded MRI examination from a custom-made phantom was loaded into the sonography system. The phantom contained spheres that were invisible to sonography and contained red dye. The red dye was visible in the biopsy if it was successful. The images were coregistered using structures visible on both sonography and MRI, and biopsies were taken. The biopsy procedure was continued until a biopsy was successful, and the number of needle passes and time spent were registered. RESULTS A total of 130 targets were hit. Ten minutes was used for loading the MRI data set and the coregistration; 94 of the 130 biopsies (72.3%) were successful at the first needle pass. The median number of needle passes until a successful biopsy was obtained was one (range, 1-7). CONCLUSION The described method was successful in obtaining an adequate sample in a phantom.

The diagnostic value of adding dynamic scintigraphy to standard delayed planar imaging for sentinel node identification in melanoma patients

PurposeThe aim of this study was to compare early dynamic imaging combined with delayed static imaging and single photon emission computed tomography (SPECT)/CT with delayed, planar, static imaging alone for sentinel node (SN) identification in melanoma patients.MethodsThree hundred and seven consecutive melanoma patients referred for SN biopsy (SNB) were examined using combined imaging. Secondary interpretation of only the delayed static images was subsequently performed. In 220 patients (72%), complete surgical and pathological information relating to the SNB was available. The number of SNs identified and number of patients with positive SNs were compared between the two interpretations of the imaging studies and, when available, related to pathology data.ResultsA slightly higher number of SNs (mean 0.12/patient) was identified when interpreting only delayed static images compared to combined imaging. In a direct patient-to-patient comparison, the number of SN(s) identified on the combined vs static images only showed moderate agreement (kappa value 0.56). In 38 patients (17%), positive SNs were identified by the combined procedure compared to 35 (16%) by static imaging only. Thus by static imaging only, tumour-positive SNs were not identified in 3 of 38 patients (8%).ConclusionFor SN identification in melanoma patients, dynamic imaging combined with delayed static imaging and SPECT/CT is superior to delayed static imaging only because the latter is more likely to fail to identify SNs containing metastases.

Development of a reliable simulation-based test for diagnostic abdominal ultrasound with a pass/fail standard usable for mastery learning

BackgroundThis study aimed to develop a test with validity evidence for abdominal diagnostic ultrasound with a pass/fail-standard to facilitate mastery learning.MethodThe simulator had 150 real-life patient abdominal scans of which 15 cases with 44 findings were selected, representing level 1 from The European Federation of Societies for Ultrasound in Medicine and Biology. Four groups of experience levels were constructed: Novices (medical students), trainees (first-year radiology residents), intermediates (third- to fourth-year radiology residents) and advanced (physicians with ultrasound fellowship). Participants were tested in a standardized setup and scored by two blinded reviewers prior to an item analysis.ResultsThe item analysis excluded 14 diagnoses. Both internal consistency (Cronbach’s alpha 0.96) and inter-rater reliability (0.99) were good and there were statistically significant differences (p < 0.001) between all four groups, except the intermediate and advanced groups (p = 1.0). There was a statistically significant correlation between experience and test scores (Pearson’s r = 0.82, p < 0.001). The pass/fail-standard failed all novices (no false positives) and passed all advanced (no false negatives). All intermediate participants and six out of 14 trainees passed.ConclusionWe developed a test for diagnostic abdominal ultrasound with solid validity evidence and a pass/fail-standard without any false-positive or false-negative scores.Key Points• Ultrasound training can benefit from competency-based education based on reliable tests.• This simulation-based test can differentiate between competency levels of ultrasound examiners.• This test is suitable for competency-based education, e.g. mastery learning.• We provide a pass/fail standard without false-negative or false-positive scores.

Evaluation of contrast-enhanced ultrasound of the pancreas combined with concurrent hormone stimulation.

PURPOSE To evaluate the potential of combined administration of the gastrointestinal hormones secretin (Secrelux) and c-terminal cholecystokinin (CCK-8 s) together with contrast-enhanced ultrasound (CE-US) to generate an extended contrast enhancement of healthy pancreatic tissue. MATERIALS AND METHODS 14 anaesthetised pigs weighing 30-35 kg were studied. After laparotomy, the pancreas was located and a B-mode examination followed by a CE-US examination of the gland was made using SonoVue 1.5 ml. After an injection of Secrelux 1 U/kg and CCK-8 s 100 pmol/kg, a second CE-US examination was conducted. The hormones and the contrast agent were administered through a catheter in the superior vena cava. The sonographic images were stored for later evaluation. RESULTS The study showed that CE-US increased the echogenicity of the pancreas by an average of 15.6 decibel (dB) (confidence intervals [CI]: 13.72, 17.42) p < 0.0001, an increase of 24%. The administration of Secrelux and CCK-8 s in combination with CE-US further increased the echogenicity of the pancreas by an average of 3% (CI: 0.36, 5.36) p = 0.028. A new sequence of hormones and CE-US 20 min after the previous injection did not induce further enhancement. The area under the curve (AUC) was significantly larger using both hormones and CE-US compared with CE-US alone by an average of 66 dBx sec (CI: 28,103) p = 0.002. CONCLUSION It is possible to generate an extended contrast enhancement of healthy pancreatic tissue using CE-US combined with the administration of the gastrointestinal hormones secretin (Secrelux) and c-terminal cholecystokinin (CCK-8 s). Our results may improve the ability to discriminate between healthy pancreatic tissue and areas with a changed blood flow due to either neoplasm or other pathological lesions.

Axillary sentinel node identification in breast cancer patients: degree of radioactivity present at biopsy is critical

Background:  The radioactivity present in the patient (Actrem) at sentinel node (SN) biopsy will depend on injected activity amount as well as on the time interval from tracer injection to biopsy, which both show great variations in the literature. The purpose of this study was to analyse the influence of varying Actrem levels on the outcome of axillary SN biopsy in patients with breast cancer (BC).

Blood vector velocity estimation using an autocorrelation approach: in vivo investigation

In conventional techniques for blood velocity esti- mation, only the axial component of the velocity vector is found. We have previously shown that it is possible to estimate the 2-D blood velocity vector both in simulations and in flow phantom experiments using a fast and inexpensive method (the transverse oscillation (TO) method) based on an autocorrelation approach. The TO method makes use of a double oscillating pulse-echo field which is created by manipulating the receive apodization function. Two receive beams are beamformed, where the lateral distance between the two beams corresponds to a 90 ◦ phase shift in the lateral direction. The TO method works at angles where conventional methods fails to estimate any blood movement, i.e. when the angle between the ultrasound beam and the velocity vector is approximately 90 ◦ . In this paper the first in-vivo color flow map (CFM) images are presented using the TO method. A 128 element 5 MHz linear array transducer was used together with the experimental ultrasound scanner RASMUS operating at a sampling frequency of 40 MHz with a pulse repetition frequency of 24 kHz. After sampling the received channel data were beamformed off-line, and a transverse oscillation period of 1 mm was created in the lateral pulse-echo field by manipulating the receive apodization function. Echo-canceling was performed by subtracting a line from the sampled data, where the line was a linear fit to the sampled data. Three different scan areas were selected: 1) The common carotid artery, 2) the common carotid artery and the jugular vein, 3) the bifurcation of the common carotid artery. In all three cases the angle between the ultrasound beams and the blood velocity vector is larger than 60 ◦ i.e. the conventional Doppler velocity estimator degrades significantly in terms of standard deviation and bias. The velocity direction and magnitude could be estimated for all cases and it was found that the blood flow is within the values given by the literature. I. INTRODUCTION