bluuebunny/crossref_metadata_2025_split huggingface dataset:
Interventional MR‐guided excisional biopsy of breast lesions
Authors: Gould Stuart William Thomas , Lamb Gabrielle , Lomax David , Gedroyc Wadislaw , Darzi Ara 
Published: March 2007

AbstractInterventional MR (IMR) machines have produced unique opportunities for image‐guided surgery. The open configuration design and fast pulse sequences allow intraoperative scanning to monitor procedures. This study was undertaken to assess the potential use of IMR for image‐guided surgery. Benign breast lesion excision was chosen as an uncomplicated surgical model. Ten female patients with known benign tumors underwent excision biopsy under general anesthesia in a Signa SP10 .5‐T IMR machine (General Electric Medical Systems, Milwaukee, WI). Lesions were localized with precontrast and postcontrast (intravenous gadolinium‐diethylenetriamine pentaacetic acid, .2 mmol/kg) fast multiplanar spoiled gradient‐recalled acquisition in the steady state (GRASS) sequences. Preoperative “real‐time” fast gradient‐recalled sequences were also obtained using the Flashpoint (General Electric Medical Systems, Milwaukee, WI) tracker device. The maximum dimensions of each lesion were measured from the resulting images. Excision was performed using titanium instruments and an ultrasonically activated scalpel. Intraoperative real‐time scanning demonstrated the resection margin and confirmed complete excision. The maximum dimensions of the macroscopic specimens were compared with those from the MR images. All tumors were visualized with the Signa scanner and real‐time imaging and the images were enhanced after intravenous contrast. Maximum dimensions on histologic examination were not significantly different from those measured from Signa (P > .17) or real‐time images (P > .4). There was no significant difference between lesion size from Signa and real‐time images (P > .25). All postprocedure scans demonstrated complete excision. There were six fibroadenomas, two foci of sclerosing adenosis, one area of fibrocystic disease, and one schwannoma. Intraoperative MR scanning reliably identifies palpable breast tumors and can accurately guide surgical excision. Further work using MR guidance can now be performed in other general surgical areas.
Invited. Predictability of the size of laser‐induced lesions in T1‐weighted MR images obtained during interstitial laser‐induced thermotherapy of benign prostatic hyperplasia
Authors: Mueller‐Lisse Ullrich G. , Heuck Andreas F. , Thoma Martin , Muschter Rolf , Schneede Peter , Weninger Ernst , Faber Sonja , Hofstetter Alfons , Reiser Maximilian F. 
Published: March 2007

AbstractThe purpose of this study was to predict diameters of lesions induced by laser‐induced thermotherapy (LITT) of benign prostatic hyperplasia (BPH) from MRI signal/tissue temperature correlations during on‐line monitoring with a temperature‐sensitive fast low‐angle shot (FLASH) sequence. Twenty LITT procedures with Nd:YAG (1,064 nm) and diode (830 nm) lasers were monitored on line with a T1‐weighted FLASH sequence at 1.5 Tesla. Interstitial prostate temperature (T) was measured on line in 10 LITT procedures and laser energy deposition in 12. Slopes of linear regression curves for signal intensity (SI) over T were applied to determine SI at 60°C to estimate diameters of intraprostatic LITT lesions. Diameters of unperfused LITT lesion cores in contrast‐enhanced T1‐weighted images served as gold standards. Linear regression curves with an average slope of −.54% SI/°C were obtained in 17 LITT procedures. Correlation coefficients were r = .92−.95 for SI/T and SI/energy deposition. Baseline variation of SI at body temperature was ±3.9%, corresponding to ±7°C. Prediction of size (13 lesions) from on‐line FLASH imaging was correct in 10 of 13, whereas 3 lesions were overestimated. Prediction of LITT lesion diameters from on‐line MRI monitoring is possible with a temperature‐sensitive FLASH sequence in the prostate. Accuracy may suffice to assign target regions of interest to tissue locations to be protected from coagulation.
Invited. MRI of laser‐induced interstitial thermal injury in an in vivo animal liver model with histologic correlation
Authors: Morrison Paul R. , Jolesz Ferenc A. , Charous Daniel , Mulkern Robert V. , Hushek Stephen G. , Margolis Randall , Fried Marvin P. 
Published: March 2007

AbstractLaser‐induced interstitial thermal therapy (LITT) is a preferred method of minimally invasive therapy. MRI is a noninvasive method by which to monitor the thermal effects of LITT. To properly control such effects, changes in MRI parameters during and after LITT should be correlated with changes in the tissue. T1‐weighted fast spin echo (FSE) MRI (1 image/10 seconds) at 1.5 T monitored LITT in vivo in rabbit liver (n = 6) using an interstitial bare delivery fiber (600‐μm diameter; 3.0 W; 1,064 nm; 150 seconds). During laser irradiation, MRI signal intensity decreased around the fiber tip; after irradiation, this hypointensity proved reversible and permanent lesions were evident. The lesions had hyperintense margins that were brighter than surrounding normal tissue (P < .001); the tissue in these bright regions was mapped to tissue necrosis characterized by the presence of thermally damaged ghost red blood cells amid generally normal hepatocytes. T1‐FSE identified the spatial extent of the LITT lesions.
MR monitoring of MR‐guided radiofrequency thermal ablation of normal liver in an animal model
Authors: Boaz Travis L. , Lewin Jonathan S. , Chung Yiu‐Cho , Duerk Jeffrey L. , Clampitt Mark E. , Haaga John R. 
Published: March 2007

AbstractThe purpose of this study was to determine the suitability of MRI to accurately detect radiofrequency (RF) thermoablative lesions created under MR guidance. In vivo RF lesions were created in the livers of six New Zealand White rabbits using a 2‐mm‐diameter titanium alloy RF electrode with a 20‐mm exposed tip and a 50‐W RF generator. This was performed using a 0.2T clinical C‐arm MR imager for guidance and monitoring. Each animal was sacrificed and gross evaluation was performed. Histologic correlation was performed on the first two animals. The MR‐compatible RF electrode was easily identified on rapid gradient‐echo images used to guide electrode placement. A single lesion was created in each rabbit liver. Lesions ranged from approximately 10 to 17 mm in diameter (mean, 13.5 mm). T2‐weighted and short T1 inversion recovery (STIR) images demonstrated lesions ranging in diameter from 12 to 18 mm (mean, 14.6 mm). Lesion dimensions determined from images closely correlated with those determined at gross examination with the discrepancy never exceeding 2 mm, for an r2 value of .87. MRI performed at the time of MR‐guided RF ablation accurately demonstrated created lesions. This modality may provide a new option for the treatment of local and regional neoplastic disease.
Invited. MRI‐guided biopsy of bone in a hybrid system
Authors: Neuerburg Joerg‐Michael , Adam Gerhard , Buecker Arno , Zilkens Karl W. , Schmitz‐Rode Thomas , Hunter David , van Vaals Joop J. , Guenther Rolf W. 
Published: March 2007

AbstractThis is a report of our experience with percutaneous, MRI‐guided biopsies in 25 patients with skeletal lesions using a 1.5‐T MR hybrid system. Twenty‐five consecutive patients with skeletal lesions were referred for MRI‐guided biopsy. Biopsies were performed with a 1.5‐T Philips Gyroscan (Philips Medical Systems, Best, The Netherlands) combined with a c‐arm fluoroscopy. Specimens were obtained percutaneously either with a 14‐ or 18‐gauge “side‐slit” type of biopsy needle (n = 10 skeletal lesions that had penetrated through the cortex), or using a prototype coaxial drill system powered either by hand or an optional motor (n = 15 skeletal lesions still covered with cortical bone). All but two biopsies could be completed within the MR unit. For one patient, who required a transpedicular approach to a lumbar vertebra, and for one child, who required general anesthesia, we decided to switch to CT guidance. In 19 of the 25 cases (17 of the 23 cases performed in MR), the sample was sufficient and the histopathologic diagnosis was confirmed. Three patients had an inadequate sample, and three others had adequate samples but inaccurate results. No procedural complications occurred. Percutaneous biopsy of skeletal lesions performed under MRI‐guidance was found to be safe and reasonably accurate. There were no procedural complications in our small series. MRI may be used as an alternative to CT, but its role vis‐à‐vis CT has yet to be ascertained.
A method for simultaneous RF ablation and MRI
Authors: Zhang Qiang , Chung Yiu‐Cho , Lewin Jonathan S. , Duerk Jeffrey L. 
Published: March 2007

AbstractRadiofrequency (RF) energy has many advantages in thermal tumor ablation protocols. With the recent development of open MRI systems, interventional MRI procedures, including thermal ablation, have become the focus of great research interest. However, the significant interference between RF generators and MR imagers has prevented simultaneous imaging and RF ablation and, until now, has limited the role of RF‐based thermal therapy in interventional MRI. Here, a simple switching circuit designed with consideration of patient safety provides compatibility between open MRI systems and RF thermal lesion generators. The experimental results show that the switching circuit allows imaging during RF ablation and opens new opportunity for MR‐guided thermal therapy.
Invited. Correlation of neuropathologic findings and phase‐based MRI temperature Maps in experimental laser‐induced interstitial thermotherapy
Authors: Schulze Christian P. , Kahn Thomas , Harth Thorsten , Schwurzmaier Hans‐Joachim , Schober Ralf 
Published: March 2007

AbstractTo investigate the correlation between the neuropathologic findings after laser‐induced interstitial thermotherapy (LITT) and MRI temperature maps during laser irradiation, a total of six pig brains from cadavers were treated with a Nd:YAG laser (λ = 1,064 nm, 3.8 W) for 15 minutes. For MRI monitoring, we used a phase‐sensitive two‐dimensional (2D) fast lowangle shot (FLASH) sequence on a 1.5‐T Magnetom SP. Temperature maps were acquired every minute (accuracy, < 1.5°C). Histopathologic methods were selected (hematoxylin and eosin stain, Masson's trichrome, Bodian silver impregnation) to demonstrate the zonal architecture of LITT lesions in ex vivo specimens. They showed extensive destruction of the nervous tissue constituents, vascular changes, and lysis of erythrocytes near the track of the laser, a transitional zone, and an 1.5‐mm broad margin with edema‐like perinuclear vacuolization. No immunoreactivity of glial fibrillary acidic protein (GFAP) could be visualized inside the lesion. In a semiquantitative evaluation, the lesion sizes were measured microscopically (mean diameter = 12.8 mm) and their margins could be defined at temperature zones of 60 to 65°C on the MRI maps.
Invited. Brain edema development after MRI‐guided focused ultrasound treatment
Authors: Mörocz István Á. , Hynynen Kullervo , Gudbjartsson HLäkon , Peled Sharon , Colucci Vincent , Jólesz Ferenc A. 
Published: March 2007

AbstractThe aim of this study was to investigate a potential technique for image‐guided minimally invasive neurosurgical interventions. Focused ultrasound (FUS) delivers thermal energy without an invasive probe, penetrating the dura mater, entering through the cerebrospinal fluid (CSF) space, or harming intervening brain tissue. We applied continuous on‐line monitoring by MRI to demonstrate the effect of the thermal intervention on the brain tissue. For this, seven rabbits had a part of their skull removed to create access for the FUS beam into the brain through an acoustic window of 11 mm in diameter. Dura was left intact and skin was sutured. One week later, the rabbits were sonicated for 3 seconds with 21 W acoustic power, and the FUS focus was visualized with a temperature‐sensitive T1‐weighted MRI pulse sequence. The tissue reaction was documented over 7 days with T2‐weighted images of the brain. The initial area of the central low signal intensity in the axial plane was .4 ± .3 mm2, and for the bright hyperintensity surrounding the lesion, it was 2.3 ± .6 mm2 (n = 7). In the coronal plane, the corresponding values were .4 ± .1 mm2 and 3.4 ± .9 mm2 (n = 5). The developing brain edema culminated 48 hours later and thereafter diminished during the next 5 days. Histology revealed a central necrosis in the white matter surrounded by edematous tissue with inflammatory cells. In summary, the image‐guided thermal ablation technique described here produced a relatively small lesion in the white matter at the targeted location. This was accomplished without opening the dura or the need for a stereotactical device. MRI allowed on‐line monitoring of the lesion setting and the deposition of thermal energy and demonstrated the tissue damage after the thermal injury.
Target definition and trajectory optimization for interactive MR‐guided biopsies of brain tumors in an open configuration MRI system
Authors: Kollias Spyros S. , Bernays Rene , Marugg Richard A. , Romanowski Ben , Yonekawa Yasuhiro , Valavanis Anton 
Published: March 2007

AbstractWe present an imaging strategy for planning and guiding brain biopsies in an open configuration MR system. Preprocedure imaging was performed in a 1.5‐T MR system and was designed to provide, in a clinically efficient manner, high resolution anatomical and functional/physiologic information for precise definition and tissue characterization of the target, aiming at optimization of the biopsy trajectory for planning a safe and accurate procedure. The interventions were performed in a .5‐T open bore magnet, and imaging was optimized to provide the imaging quality and temporal resolution necessary for performing the procedure interactively in near real time. Brain biopsies of 21 patients were performed in a 10‐month period. Segmentation and surface rendering analysis of the lesions and vascular structures and dynamic MR perfusion and cortical activation studies provided an efficient and comprehensive way to appreciate the relationship of the target to surrounding vital structures, improved tissue characterization and definition of the tumor margins, and demonstrated the location of essential cortex, allowing appropriate placement of the burr hole and choice of optimal trajectory. Interactive protocols provided good visualization of the target and the interventional devices and offered the operator real‐time feedback and control of the procedure. No complications were encountered. Advanced methods of image acquisition and processing for accurate planning of interventional brain procedures and interactive imaging with MR guidance render feasible the performance of safe and accurate neurointerventional procedures.
Invited. Calibration of water proton chemical shift with temperature for noninvasive temperature imaging during focused ultrasound surgery
Authors: Kuroda Kagayaki , Chung Andrew H. , Hynynen Kullervo , Jolesz Ferenc A. 
Published: March 2007

AbstractThe present work was performed to calibrate water proton chemical shift change with tissue temperature in vivo to establish a method of quantitative temperature imaging during focused ultrasound surgery. The chemical shift change measured with a phase‐mapping method using spoiled gradient‐recalled acquisition in steady state (SPGR) (TR = 26 msec, TE = 12.8 msec, matrix = 256 × 128) was calibrated with the corresponding temperature elevation (0–50°C, 32–84°C in absolute temperature) measured with a copper‐constantan thermocouple (.05‐mm‐diameter bare wires) in rabbit skeletal muscle (16 animals) under focused ultrasound exposures (10–100 W radiofrequency [RF] power, 20‐second sonication). A linear calibration with a regression coefficient of (−8.76 ± .69) × 10−3 ppm/ °C (P < .01 [P, significance level]) was obtained. Temperature distributions during a 20‐second sonication were visualized every 3.3 seconds with a 2.3‐mm3 spatial resolution and 4°C temperature uncertainty.
Regions of interest tracking in temporal scans based on statistical analysis of gray scale and edge properties and registration of images
Authors: Saeed Nadeem , Hajnal Joseph V. , Oatridge Angela , Young Ian R. 
Published: March 2007

AbstractPrecise measurement of T1 is needed for its use in temperature monitoring in vivo. Movement of tissue relative to fixed regions of interest can result in large variations in apparent T1, with consequent substantial errors in the measured temperature. This paper evaluates methods of tracking regions of interest as tissue moves during a study in an effort to minimize errors from this cause. Tracking techniques evaluated are based on maintaining constant gray scale levels, locating nearby edges and maintaining position relative to them, and global image registration.
Invited. Remember true FISP? a high SNR, near 1‐second imaging method for T2‐like contrast in interventional MRI at .2 T
Authors: Duerk Jeffrey L. , Lewin Jonathan S. , Wendt Michael , Petersilge Cheryl 
Published: March 2007

AbstractClinical requirements for interventional MRI (I‐MRI) monitoring of needle placement or thermal ablation demand rapid (near‐real‐time) image acquisition rates, high spatial resolution, and T2 weighting. Experimental analysis performed earlier (see ref. 8) suggests that many sequences used for either rapid scanning or T2 weighting at high fields fail to meet both the speed (conventional spin echo [SE], turbo SE) or contrast (ie, fast low‐angle shot [FLASH], fast imaging with steady state precession [FISP]) requirements when used at .2 T. In this work, we revisited a number of pulse sequences advocated primarily for higher field applications requiring T2 weighting and found that refocused steady state coherent pulse sequences, aka, true FISP sequences, performed superiorly in achieving both speed and T2 contrast requirements for I‐MRI at .2 T. This work focuses on our experience with this new/old technique in the I‐MRI setting and describes how one can take advantage of the low field strength and modest inhomogeneity of .2 T (and similar) systems to design pulse sequences that balance TE, TR (and hence T2 dephasing), and resonant offset frequency effects to provide images with the desired contrast and minimal artifactual field inhomogeneity “banding.” At high flip angles (∼90°), reasonably short TEs (∼5 msec) and short TRs (∼ 10 msec), we have used this method in our last 25 I‐MRI procedures (biopsies and/or radiofrequency [RF] thermal ablations) and found these sequences to be extremely useful in both needle localization phases of I‐MRI biopsy procedures, RF thermal ablation electrode guidance, and posttherapy imaging assessment. Design methods and clinical I‐MRI cases are presented that highlight these points.
Invited. Visualization of MR‐compatible catheters by electrically induced local field inhomogeneities: Evaluation in vivo
Authors: Adam Gerhard , Glowinski Arndt , Neuerburg Jörg , Bücker Arno , van Vaals Joop J. , Günther Rolf W. 
Published: March 2007

AbstractThe purpose of this study was to assess the feasibility of a newly developed field inhomogeneity catheter for interventional MRI in vivo. Different prototypes of a field inhomogeneity catheter (pigtail and multipurpose configuration, balloon catheters) were investigated in pigs. The catheters were introduced in Seldinger technique via the femoral vessels over a guidewire on an interventional MR system (Philips Gyroscan NT combined with a C‐arm fluoroscopy unit [Philips BV 212]). Catheters were placed in veins and arteries. The catheter position was controlled by a fast gradient‐echo sequence (turbo field echo [TFE]). Catheters were introduced over a guidewire without complications in all cases. Using the field inhomogeneity concept, catheters were easily visualized in the inferior vena cava and the aorta by the fast gradient‐echo technique on MR in all cases. Although aortic branches were successful cannulated, the catheters were not well displayed by the TFE technique due to the complex and tortuous anatomy. All animals survived the experiments without complications. MR‐guided visualization of a field inhomogeneity catheter is a simple concept that can be realized on each MR scanner and may allow intravascular MR‐guided interventions in future.
An expandable intravenous RF coil for arterial wall imaging
Authors: Martin Alastair J. , McLoughlin Raymond F. , Chu Kenneth C. , Barberi Enzo A. , Rutt Brian K. 
Published: March 2007

AbstractAn intravenous (iv) radiofrequency (RF) coil is proposed as a means of obtaining high resolution images of artery wall. The anatomic positioning of peripheral artery/vein pairs was investigated and a phantom mimicking the iliac artery/vein pair was constructed. Imaging results, comparing iv coils with external coils, demonstrated a potential 15‐ to 20‐fold increase in signal‐to‐noise ratio (SNR) with iv coils. The SNR benefit was measured over a cylindrical volume, adjacent to the coil, and typical of artery position. Prototype expandable iv coils were constructed of Cu‐Be loops and introduced via an 8‐Fr catheter. The effects of local and remote iv coil tuning were investigated and local tuning was found to provide significant SNR benefits. The in vivo performance of iv RF coils was demonstrated in a porcine animal model. The iv coils were found to be an excellent alternative to intraarterial coils.
Preliminary clinical experience with laser‐induced interstitial thermotherapy in patients with hepatocellular carcinoma
Authors: Bremer Christoph , Allkemper Thomas , Menzel Josef , Sulkowski Udo , Rummeny Ernst , Reimer Peter 
Published: March 2007

AbstractThe purpose of this preliminary study was to evaluate whether laser‐induced interstitial thermotherapy (LITT) may be used for palliative treatment of localized hepatocellular carcinomas (HCC). We applied LITT to two patients suffering from unresectable localized hepatocellular carcinomas of different sizes (2.5 and 4 cm). LITT was performed with an Nd:YAG laser (1,064 nm) at 5 W laser power (15–20 minutes). Thermometry during LITT was performed by MRI using a temperature‐sensitive T1‐weighted fast low‐angle shot (FLASH) sequence. Follow‐up for local tumor control was performed by MRI and ultrasound. LITT was well tolerated and no adverse events occurred during or after LITT; no secondary liver lesions were seen in the follow‐up (11 or 12 months, respectively). Only minimal tumor growth was observed in the larger HCC (from 4 to 5 cm), whereas the smaller HCC remained unchanged in size during 11 months of follow‐up. We conclude that LITT might be an effective minimally invasive palliative treatment option for patients with small unresectable HCC.