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C M Tempany

Publications and source records attributed to C M Tempany.

At least 19 recordsLinked to original sources
PubMed2006

Robot-assisted needle placement in open-MRI: system architecture, integration and validation.

This work describes an integrated system for planning and performing percutaneous procedures-such as prostate biopsy-with robotic assistance under MRI-guidance. The physician interacts with a planning interface in order to specify the set of desired needle trajectories, based on anatomical structures and lesions observed in the patient's MR images. All image-space coordinates are automatically computed, and used to position a needle guide by means of an MRI-compatible robotic manipulator, thus avoiding the limitations of the traditional fixed needle template. Direct control of real-time imaging aids visualization of the needle as it is manually inserted through the guide. Results from in-scanner phantom experiments are provided.

Biopsy, Needle↗
PubMed2001

A practical method to achieve prostate gland immobilization and target verification for daily treatment.

PURPOSE: A practical method to achieve prostate immobilization and daily target localization for external beam radiation treatment is described. METHODS AND MATERIALS: Ten patients who underwent prostate brachytherapy using permanent radioactive source placement were selected for study. To quantify prostate motion both with and without the presence of a specially designed inflatable intrarectal balloon, the computerized tomography-based coordinates of all intraprostatic radioactive sources were compared over 3 consecutive measurements at 1-min intervals. RESULTS: The placement and inflation of the intrarectal balloon were well tolerated by all patients. The mean (range) displacement of the prostate gland when the intrarectal balloon was present vs. absent was 1.3 (0-2.2) mm vs. 1.8 (0-9.1) mm (p = 0.03) at 2 min respectively. The maximum displacement in any direction (anterior-posterior, superior-inferior, or right-left) when the intrarectal balloon was inflated vs. absent was reduced to < or =1 mm from 4 mm. CONCLUSIONS: Both prostate gland immobilization and target verification are possible using a specially designed inflatable intrarectal balloon. Using this device, the posterior margin necessary on the lateral fields to ensure dosimetric coverage of the entire prostate gland could be safely reduced to 5 mm and treatment could be set up and verified using a lateral portal image.

Brachytherapy↗
PubMed2001

Three-dimensional magnetic resonance imaging of fetal brains.

We assessed ten prenatal magnetic resonance imaging(MRI) scans for fetal brain anomalies, and identified eight that were suitable for post-processing. Anatomical abnormalities were assessed on three-dimensional (3D) models and compared with two-dimensional (2D) imaging. We calculated the volumes of the intracranial ventricles and of a periventricular haemorrhage. In three cases, additional clinical information was obtained. 3D modelling of the brain in-utero is possible and can be used to plan treatment.

Brain↗
PubMed2001

Advances in biomedical imaging.

In the 21st century, diseases will be diagnosed and treated using increasingly less invasive, more sophisticated imaging and image-guided procedures. During the past 100 years, the field of biomedical imaging has developed from Roentgen's original discovery of the x-ray to the imaging tools of today, such as magnetic resonance imaging, computed tomography, positron emission tomography, and ultrasonography. The benefits of using these sophisticated noninvasive imaging tools are already evident: more accurate and timely diagnosis of disease has translated into improved patient care. Recent advances in imaging research have shown the potential to change many aspects of clinical medicine within the next decade. Major new areas of research focus on development of the molecular, functional, cellular, and genetic imaging tools of the future, aided by new information technology and image fusion/integration capabilities. Image-guided therapy is growing rapidly, with advances in computer science, technology, and noninvasive treatment methods, such as focused ultrasonography. Undoubtedly, these and other new imaging techniques will enhance the ability to accurately diagnose and recognize disease and allow understanding of the molecular mechanisms of diseases and their respective responses to therapy. Given this explosion in new technologies, the next 25 years promise to result in dramatic changes in diagnostic imaging, particularly with respect to detection and recognition of disease.

Computational Biology↗
PubMed2001

Prenatal diagnosis of pyruvate dehydrogenase deficiency using magnetic resonance imaging.

INTRODUCTION: Pyruvate dehydrogenase deficiency is an inherited inborn error of metabolism associated with early neonatal death and long-term neurologic sequelae in survivors. Prenatal diagnosis currently relies on isolation of fetal cells for subsequent genetic and/or biochemical studies. Magnetic resonance imaging and magnetic resonance spectroscopy have been used on occasion for both postnatal diagnosis and management of pyruvate dehydrogenase deficiency. We illustrate a case in which these non-invasive modalities also prove useful for prenatal diagnosis of this condition. CASE: A 31-year-old multipara with a history of two prior infants affected with pyruvate dehydrogenase deficiency presented with a spontaneous dichorionic, diamniotic twin pregnancy. Magnetic resonance imaging and magnetic resonance spectroscopy were performed on both fetuses. Magnetic resonance imaging of the presenting (male) fetus demonstrated mild ventriculomegaly, increased extracerebrospinal fluid, and decreased cortical sulcation and gyration. The non-presenting (female) fetus was structurally normal. Magnetic resonance spectroscopy spectra were obtained for both fetuses, and were normal. The diagnosis of pyruvate dehydrogenase deficiency was made in the presenting fetus after delivery on the basis of subsequent mortality from severe lactic acidosis. CONCLUSION: Prenatal MR imaging of the fetal brain can be used for prenatal diagnosis in fetuses at risk for pyruvate dehydrogenase deficiency. Prenatal MR spectroscopy, although technically feasible, does not appear to have a role in the prenatal diagnosis of this condition.

Acidosis, Lactic↗
PubMed2001

Bayesian regression methodology for estimating a receiver operating characteristic curve with two radiologic applications: prostate biopsy and spiral CT of ureteral stones.

RATIONALE AND OBJECTIVES: The authors evaluated two Bayesian regression models for receiver operating characteristic (ROC) curve analysis of continuous diagnostic outcome data with covariates. MATERIALS AND METHODS: Full and partial Bayesian regression models were applied to data from two studies (n = 180 and 100, respectively): (a) The diagnostic value of prostate-specific antigen (PSA) levels (outcome variable) for predicting disease after radical prostatectomy (gold standard) was evaluated for three risk groups (covariates) based on Gleason scores. (b) Spiral computed tomography was performed on patients with proved obstructing ureteral stones. The predictive value of stone size (outcome) was evaluated along with two treatment options (gold standard), as well as stone location (in or not in the ureterovesical junction [UVJ]) and patient age (covariates). Summary ROC measures were reported, and various prior distributions of the regression coefficients were investigated. RESULTS: (a) In the PSA example, the ROC areas under the full model were 0.667, 0.769, and 0.703, respectively, for the low-, intermediate-, and high-risk groups. Under the partial model, the area beneath the ROC curve was 0.706. (b) The ROC areas for patients with ureteral stones in the UVJ decreased dramatically with age but otherwise were close to that under the partial model (ie, 0.774). The prior distribution had greater influence in the second example. CONCLUSION: The diagnostic tests were accurate in both examples. PSA levels were most accurate for staging prostate cancer among intermediate-risk patients. Stone size was predictive of treatment option for all patients other than those 40 years or older and with a stone in the UVJ.

Adult↗
PubMed2001

Isolated calf vein thrombosis: comparison of MR venography and conventional venography after initial sonography in symptomatic patients.

RATIONALE AND OBJECTIVES: The authors performed this study to compare magnetic resonance (MR) venography and conventional venography in the diagnosis of deep venous thrombosis (DVT) in the calf after sonography. MATERIALS AND METHODS: Sonography was performed in 595 patients who were suspected of having lower-extremity DVT. Patients with positive above-knee duplex sonograms, allergy to iodinated contrast material, renal insufficiency, or cardiac pacemakers and patients who were obese were excluded. The remaining 73 patients were asked to undergo MR venography and conventional venography. All studies were to be performed within 48 hours of the clinical diagnosis and according to standard clinical practice. Images were interpreted by radiologists who were blinded to the results of other modalities. Two separate analyses were performed: one in which conventional venography was used as the standard of reference, and one in which the presence of at least two positive studies for thrombus was considered diagnostic. RESULTS: Although 36 patients agreed to participate in the study, only 14 underwent MR venography and conventional venography within 48 hours of the clinical diagnosis. With use of any two positive studies for confirmation, acute DVT was diagnosed in three patients. Conventional venography depicted two of the three cases, whereas sonography and MR venography each depicted all three. The findings were concordant in only five of the 14 patients. CONCLUSION: Moderate discrepancy among modalities was demonstrated. This suggests radiologists should undertake comparisons among these three modalities for the detection of calf DVT. In patients with a high clinical suspicion, a second modality may be useful if the initial study is negative.

Adult↗
PubMed2001

Evaluation of three-dimensional finite element-based deformable registration of pre- and intraoperative prostate imaging.

In this report we evaluate an image registration technique that can improve the information content of intraoperative image data by deformable matching of preoperative images. In this study, pretreatment 1.5 tesla (T) magnetic resonance (MR) images of the prostate are registered with 0.5 T intraoperative images. The method involves rigid and nonrigid registration using biomechanical finite element modeling. Preoperative 1.5 T MR imaging is conducted with the patient supine, using an endorectal coil, while intraoperatively, the patient is in the lithotomy position with a rectal obturator in place. We have previously observed that these changes in patient position and rectal filling produce a shape change in the prostate. The registration of 1.5 T preoperative images depicting the prostate substructure [namely central gland (CG) and peripheral zone (PZ)] to 0.5 T intraoperative MR images using this method can facilitate the segmentation of the substructure of the gland for radiation treatment planning. After creating and validating a dataset of manually segmented glands from images obtained in ten sequential MR-guided brachytherapy cases, we conducted a set of experiments to assess our hypothesis that the proposed registration system can significantly improve the quality of matching of the total gland (TG), CG, and PZ. The results showed that the method statistically-significantly improves the quality of match (compared to rigid registration), raising the Dice similarity coefficient (DSC) from prematched coefficients of 0.81, 0.78, and 0.59 for TG, CG, and PZ, respectively, to 0.94, 0.86, and 0.76. A point-based measure of registration agreement was also improved by the deformable registration. CG and PZ volumes are not changed by the registration, indicating that the method maintains the biomechanical topology of the prostate. Although this strategy was tested for MRI-guided brachytherapy, the preliminary results from these experiments suggest that it may be applied to other settings such as transrectal ultrasound-guided therapy, where the integration of preoperative MRI may have a significant impact upon treatment planning and guidance.

Biophysical Phenomena↗
PubMed2001

Primary versus secondary ovarian malignancy: imaging findings of adnexal masses in the Radiology Diagnostic Oncology Group Study.

PURPOSE: To analyze ultrasonographic (US), computed tomographic (CT), and magnetic resonance (MR) imaging features of primary and secondary ovarian malignant neoplasms to determine if there is any significant difference in their appearance. MATERIALS AND METHODS: Analysis of the multi-institutional Radiology Diagnostic Oncology Group data revealed 86 patients with primary ovarian carcinoma and 24 patients with a secondary ovarian neoplasm. Numerous imaging features that had been recorded for the adnexal masses with each imaging modality were reviewed and compared between primary and secondary malignant ovarian neoplasms. RESULTS: Of the imaging features assessed with all three modalities, multilocularity as determined at US (P =.02) or MR imaging (P: =.01) was the only significant feature. At US, 30 (37%) of 81 primary ovarian cancers were multilocular, whereas only three (12%) of 24 metastatic neoplasms were multilocular. At MR imaging, 40 (74%) of 54 primary ovarian cancers were multilocular, whereas only five (36%) of 14 metastatic neoplasms were multilocular. Neither a predominately solid appearance nor bilaterality was significantly different between primary and secondary neoplasms. CONCLUSION: For malignant ovarian masses, multilocularity at MR imaging or US favors the diagnosis of primary ovarian malignancy rather than secondary neoplasm, but it is difficult to accurately distinguish between primary and secondary ovarian malignancies.

Adult↗
PubMed2001

MR imaging-guided prostate biopsy with surgical navigation software: device validation and feasibility.

Magnetic resonance (MR) imaging--guided prostate biopsy in a 0.5-T open imager is described, validated in phantom studies, and performed in two patients. The needles are guided by using fast gradient-recalled echo and T2-weighted fast spin-echo images. Surgical navigation software provided T2-weighted images critical to targeting the peripheral zone and the tumor. MR imaging can be used to guide prostate biopsy.

Biopsy, Needle↗
PubMed2000

Optimizing target coverage by dosimetric feedback during prostate brachytherapy.

PURPOSE: Postimplant dosimetry of permanent prostate implants shows a loss of coverage compared to the preplan. One contributing factor is needle misplacement. The significance of needle misplacement and the clinical utility of dosimetric feedback were analyzed in the setting of interventional magnetic resonance (IMR) guided prostate brachytherapy. METHODS AND MATERIALS: Information provided by an intraoperative planning system was analyzed for 10 patients. Needle misplacement was measured and the dosimetric consequences calculated. Additional catheters and sources were placed following the insertion of all planned catheters to compensate for nonideal needle placement. RESULTS: Source misplacement ranged from 0.0 to 1.0 cm (median, 0.3 cm). The resulting loss of coverage ranged from 1% to 13%, and the intraoperative dosimetric feedback allowed a recovery of from 0% to 12% coverage. Between 0 and 3 (median, 2) additional needles and from 0 to 10 (median, 8) additional sources were required to restore coverage of the target. Final planned coverage exceeded 94% for all patients. CONCLUSION: The discrepancy between planned and achieved needle placement leads to a loss of dosimetric coverage of the target volume. Dosimetric feedback allows compensation for needle divergence. The technique of real-time dosimetric feedback does not require an IMR system, and could be generalized to ultrasound-guided implants.

Brachytherapy↗
PubMed2000

Identifying the predictors of acute urinary retention following magnetic-resonance-guided prostate brachytherapy.

PURPOSE: Larger prostate gland volumes have been associated with long-term urinary morbidity in prostate interstitial radiation therapy utilizing ultrasound image guidance technique. This study was performed to identify the clinical and technical predictors of acute urinary retention following magnetic-resonance (MR)-guided prostate interstitial brachytherapy. METHODS AND MATERIALS: Fifty patients underwent MR-guided prostate brachytherapy between December 1997 and March 1999. Patient selection was limited to men with stage T1cNXM0 disease, PSA of less than10 ng/mL, biopsy Gleason score not more than 3 + 4, and endorectal coil MR stage T2 disease. Dosimetry plans were developed in the operating room and (125)Iodine sources were implanted using MR real-time guidance. The peripheral zone (PZ) of the prostate gland was defined as the clinical target volume (CTV) and the minimum prescribed dose to the CTV was 137 Gy. The volumes of the PZ, transition zone (TZ), and total prostate gland volume were also determined by MR. Individual source strength ranged from 0.35 to 0.54 microGym(2)/h (NIST 99, median 0.46 microGym(2)/h) and the total implanted activity ranged from 17.0 to 43.1 mCi (median, 28.1 mCi) using 43-120 seeds (median, 79). The seeds were placed using MR-compatible biopsy needles (14-28, median, 19). RESULTS: The ability of clinical (MR defined prostate, PZ, and TZ volumes) and technical (number of catheters, number of seeds implanted, and total activity) factors to predict AUR for 50 men undergoing MR-guided prostate interstitial brachytherapy were evaluated using univariable and logistic regression multivariable analyses. Six men (12%) experienced AUR within 24 h after removal of the Foley catheter subsequent to prostate brachytherapy. The total number of seeds (p = 0.05), MR determined prostate volume (p < 0.01), and the MR-determined TZ volume (p < 0.01) were significant predictors of AUR on univariable analysis. Utilizing a multivariable logistic regression analysis, the TZ volume was the only significant predictor of AUR (p < 0.01). The prostate volume is highly correlated to the TZ volume (Spearman correlation coefficient of 0. 91) and was thus significant in the univariable analysis; however, the prostate volume did not add prognostic value in multivariable analysis. CONCLUSION: Benign prostatic hyperplasia (BPH) resulting in an enlarged TZ volume, is the most important predictor of AUR following MR-guided prostate interstitial radiation therapy. Although AUR was significant (60%) in men with moderate BPH (TZ volume >/= 50 cc), it was also self-limiting.

Analysis of Variance↗
PubMed2000

A clinical method for real-time dosimetric guidance of transperineal 125I prostate implants using interventional magnetic resonance imaging.

PURPOSE: The clinical utility of an interventional magnetic resonance (IMR)-guided implant technique with real-time dosimetric feedback is presented. METHODS AND MATERIALS: The work was carried out at a IMR unit at Brigham and Women's Hospital. Planning and dosimetric feedback were provided by a software system that provides an interface to the IMR images, anatomy demarcation, template registration, dose calculation engine for planning, and evaluating the implant. Planning during the procedure permits the incorporation of actual needle trajectories in the dose calculations. RESULTS: Fifteen patients were planned in the treatment position. During source placement, actual needle locations were incorporated into the dose calculations. After accounting for the observed needle trajectories of the planned needles, 14 of 15 patients (93%) required additional sources to achieve the desired coverage of the target volume. CONCLUSION: A brachytherapy implant procedure which provides clinically significant advances has been implemented. Specifically, the planning system allows dosimetric validation of the needle placement. This procedure is effective in delivering brachytherapy to the target volume and assuring that the implant is delivered in accordance with the preplan. The dosimetric feedback could be incorporated in ultrasound-guided implants.

Brachytherapy↗
PubMed2000

Real-time magnetic resonance imaging-guided brachytherapy in the treatment of selected patients with clinically localized prostate cancer.

BACKGROUND AND PURPOSE: A real-time three-dimensional magnetic resonance imaging (MRI)-guided implant technique has been designed and implemented. This report summarizes the dosimetry achieved and the acute morbidity in the first patients. PATIENTS AND METHODS: To date, 43 patients with clinical stage T(1c)N(X)M(0) prostate cancer, serum prostate specific antigen <10 ng/mL, and biopsy Gleason score no higher than 3 + 4 have been treated. The procedure was performed using an open magnet, with axial T1-weighted and fast spin echo images. The prescribed minimum radiation dose to the peripheral zone was 160 Gy. The total activity implanted ranged from 18.8 to 47.5 mCi using 43 to 120 (median 80) (125)I seeds. Dosimetric analyses were performed intraoperatively in real time for the tumor, anterior rectal wall, and prostatic urethra. RESULTS: The percent of the clinical target volume receiving the prescription dose was 89% to 99% (median 96%). Using a conservative estimate of 164 Gy, no more than 9% of the urethral volume exceeded the tolerated dose. Using an estimated tolerated dose of 82 Gy, 30% to 100% (median 68%) of the anterior rectal wall volume was within the dose limit. Thirty-nine patients voided spontaneously within 3 hours of Foley catheter discontinuation, although four patients required recatheterization for a period. No patient reported gastrointestinal or sexual dysfunction during the first postoperative month. CONCLUSION: A real-time MR-guided technique can achieve a minimum of 89% coverage of the tumor volume while maintaining the prostatic urethra and most of the anterior rectal wall below tolerance levels. Acute morbidity was minimal. Further follow-up is needed to ascertain the impact on cancer control and quality of life.

Aged↗
PubMed2000

Interventional and intraoperative magnetic resonance imaging.

The goal of the Image Guided Therapy Program, as the name implies, is to develop the use of imaging to guide minimally invasive therapy. The program combines interventional and intraoperative magnetic resonance imaging (MRI) with high-performance computing and novel therapeutic devices. In clinical practice the multidisciplinary program provides for the investigation of a wide range of interventional and surgical procedures. The Signa SP 0.5 T superconducting MRI system (GE Medical Systems, Milwaukee, WI) has a 56-cm-wide vertical gap, allowing access to the patient and permitting the execution of interactive MRI-guided procedures. This system is integrated with an optical tracking system and utilizes flexible surface coils and MRI-compatible displays to facilitate procedures. Images are obtained with routine pulse sequences. Nearly real-time imaging, with fast gradient-recalled echo sequences, may be acquired at a rate of one image every 1.5 s with interactive image plane selection. Since 1994, more than 800 of these procedures, including various percutaneous procedures and open surgeries, have been successfully performed at Brigham and Women's Hospital (Boston, MA).

Biomedical Engineering↗