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Biomedical subjects

Julia R Fielding

Publications and source records attributed to Julia R Fielding.

17 recordsLinked to original sources
PubMed2006

Virtual pyeloscopy using volumetric depth peeling.

RATIONALE AND OBJECTIVES: The aim of the study is to test a new volume-rendering method, volumetric depth peeling (VDP), for use in virtual pyeloscopy. MATERIALS AND METHODS: VDP was applied to axial contrast-enhanced source computed tomographic (CT) images and coronal reformatted maximum intensity projections of three contrast-filled gloves containing objects of varying density. Similar renderings were performed on CT urograms performed to evaluate hematuria (n = 20). Renderings were assessed for anatomic appearance of ureters and specific calyces in comparison with source images. RESULTS: Objects of soft-tissue and calcific density ranging in size from 4 to 20 mm were identified by using VDP within the glove phantoms. Normal and deformed renal calyces were well visualized by using VDP; however, two stones were not identified. The minimal ureteral width that could be visualized was 3 mm. CONCLUSION: VDP may be a useful technique for virtual pyeloscopy providing that a robust and user-friendly computer interface can be developed.

Endoscopy↗
PubMed2006

Endoanal ultrasound findings and fecal incontinence symptoms in women with and without recognized anal sphincter tears.

OBJECTIVE: To estimate whether endoanal ultrasound findings are more prevalent in primiparous women with a history of anal sphincter tear than in women without this history and whether the findings are associated with fecal incontinence symptoms. METHODS: A total of 251 primiparous women at seven clinical sites underwent standardized ultrasound assessment of the internal and external anal sphincter 6-12 months after delivery. Participants were women in the three cohorts of the Childbirth and Pelvic Symptoms Study: 1) women with clinically evident third- or fourth-degree tear at vaginal delivery (n=106); 2) no tear at vaginal delivery (n=106); and 3) cesarean delivery without labor (n=39). Women completed the Fecal Incontinence Severity Index to assess fecal incontinence symptoms. RESULTS: Thirty-five percent of the sphincter tear group exhibited internal sphincter gaps compared with 3% of vaginal controls (odds ratio [OR] 18.4, 95% confidence interval [CI] 5.5-62.1) and 10% of cesarean controls. External sphincter gaps were identified in 51% of the tear group compared with 31% of vaginal controls (OR 2.3, 95% CI 1.3-4.0) and 28% of cesarean controls. In the tear group, fecal incontinence severity was greater in those with internal sphincter gaps compared with those with no internal sphincter gaps (Fecal Incontinence Severity Index score 6.6+/-8.3 compared with 3.3+/-6.1, P=.02), as well as in those with external sphincter gaps (6.1+/-8.4 compared with 2.7+/-5.0, P=.01), and greatest in those with both internal and external sphincter gaps compared with at least one gap not present (7.2+/-8.1 compared with 3.4+/-6.4, P=.003). CONCLUSION: Anal sphincter gaps detected by ultrasonography are prevalent in postpartum primiparous women with a history of sphincter tear and are associated with fecal incontinence severity. LEVEL OF EVIDENCE: II-2.

Adult↗
PubMed2004

Levator ani thickness variations in symptomatic and asymptomatic women using magnetic resonance-based 3-dimensional color mapping.

OBJECTIVE: This study was undertaken to develop and test a 3-dimensional (3D) color thickness mapping technique on levator ani imaged with magnetic resonance imaging (MRI). METHODS: Supine MRI datasets from 30 women were studied: 10 asymptomatic, 10 with urodynamic stress incontinence, and 10 with pelvic organ prolapse. Levators were manually outlined, and thickness mapping applied. Three-dimensional models were colored topographically, reflecting levator thickness. Thickness and occurrences of absent levator substance (gaps) were compared across the 3 groups, using nonparametric statistical tests. RESULTS: Color thickness mapping was successful in all subjects. There were statistically significant differences in thickness and gap percentages among the 3 groups of women, with thicker, bulkier levators in asymptomatic women, compared with women with prolapse or urodynamic stress incontinence. CONCLUSION: Color thickness mapping is feasible. It may be used to compare levators in symptomatic and asymptomatic women, to study relationships between levator thickness and pelvic floor dysfunction. This technique can be used in larger studies for hypothesis testing.

Adult↗
PubMed2004

What is evidence-based medicine?

RATIONALE AND OBJECTIVES: In this review article, we present the definition and useful concepts of evidence-based medicine (EBM). The principles of EBM are provided and major steps of practicing EBM are described. MATERIALS AND METHODS: We emphasize the importance of the Cochrane Collaboration (see http://www.cochrane.org), which initiated the research and practice in this area. Because it can be difficult to systematically access and review individual research studies, it is often useful to focus on a critical overview of clinical trials by conducting a meta-analysis. RESULTS: Useful literature and resources related to meta-analysis are provided. CONCLUSION: Statistical methods for evaluating radiologic diagnostic performances derived from meta-analysis are summarized, with a special focus on summary outcomes measures.

Evidence-Based Medicine↗
PubMed2003

Hypothesis testing I: proportions.

Statistical inference involves two analysis methods: estimation and hypothesis testing, the latter of which is the subject of this article. Specifically, Z tests of proportion are highlighted and illustrated with imaging data from two previously published clinical studies. First, to evaluate the relationship between nonenhanced computed tomographic (CT) findings and clinical outcome, the authors demonstrate the use of the one-sample Z test in a retrospective study performed with patients who had ureteral calculi. Second, the authors use the two-sample Z test to differentiate between primary and metastatic ovarian neoplasms in the diagnosis and staging of ovarian cancer. These data are based on a subset of cases from a multiinstitutional ovarian cancer trial conducted by the Radiologic Diagnostic Oncology Group, in which the roles of CT, magnetic resonance imaging, and ultrasonography (US) were evaluated. The statistical formulas used for these analyses are explained and demonstrated. These methods may enable systematic analysis of proportions and may be applied to many other radiologic investigations.

Diagnostic Imaging↗
PubMed2003

MR imaging of the female pelvis.

MR imaging has become a valuable modality in the evaluation of the female pelvis. In many cases, it follows the performance of HSG or US. These cases include infertility and pelvic pain. In some cases, it should serve as the test of choice. This is true in the local staging of cervical cancer and the evaluation of pain or disability in the pregnant patient. Finally, in the evaluation of advanced gynecologic cancers, it is usually a secondary choice with CT preferred.

Female↗
PubMed2003

MR imaging of pelvic floor relaxation.

The wide variety of available surface coils, pulse sequences, and post-processing techniques make MR imaging a useful clinical and research tool for evaluation of pelvic floor relaxation. Cases of isolated cystocele do not require imaging; however, in cases in which multiple compartments of the pelvis are involved or the patient has failed prior surgery, MR imaging should be considered for preoperative planning.

Aged↗
PubMed2003

Statistical validation based on parametric receiver operating characteristic analysis of continuous classification data.

RATIONALE AND OBJECTIVES: The accuracy of diagnostic test and imaging segmentation is important in clinical practice because it has a direct impact on therapeutic planning. Statistical validations of classification accuracy was conducted based on parametric receiver operating characteristic analysis, illustrated on three radiologic examples, MATERIALS AND METHODS: Two parametric models were developed for diagnostic or imaging data. Example 1: A semi-automated fractional segmentation algorithm was applied to magnetic resonance imaging of nine cases of brain tumors. The tumor and background pixel data were assumed to have bi-beta distributions. Fractional segmentation was validated against an estimated composite pixel-wise gold standard based on multi-reader manual segmentations. Example 2: The predictive value of 100 cases of spiral computed tomography of ureteral stone sizes, distributed as bi-normal after a non-linear transformation, under two treatment options received. Example 3: One hundred eighty cases had prostate-specific antigen levels measured in a prospective clinical trial. Radical prostatectomy was performed in all to provide a binary gold standard of local and advanced cancer stages. Prostate-specific antigen level was transformed and modeled by bi-normal distributions. In all examples, areas under the receiver operating characteristic curves were computed. RESULTS. The areas under the receiver operating characteristic curves were: Example 1: Fractional segmentation of magnetic resonance imaging of brain tumors: meningiomas (0.924-0.984); astrocytomas (0.786-0.986); and other low-grade gliomas (0.896-0.983). Example 3: Ureteral stone size for treatment planning (0.813). Example 2: Prostate-specific antigen for staging prostate cancer (0.768). CONCLUSION: All clinical examples yielded fair to excellent accuracy. The validation metric area under the receiver operating characteristic curves may be generalized to evaluating the performances of several continuous classifiers related to imaging.

Algorithms↗
PubMed2003

Tumor detection in the bladder wall with a measurement of abnormal thickness in CT scans.

Virtual cystoscopy is a developing technique for bladder cancer screening. In a conventional cystoscopy, an optical probe is inserted into the bladder and an expert reviews the appearance of the bladder wall. Physical limitations of the probe place restrictions on the examination of the bladder wall. In virtual cystoscopy, a computed tomography (CT) scan of the bladder is acquired and an expert reviews the appearance of the bladder wall as shown by the CT. The task of identifying tumors in the bladder wall has often been done without extensive computational aid to the expert. We have developed an image processing algorithm that aids the expert in the detection of bladder tumors. Compared with an expert observer reading the CT, our algorithm achieves 89% sensitivity, 88% specificity, 48% positive predictive value, and 98% negative predictive value.

Anatomy, Cross-Sectional↗
PubMed2003

Percutaneous biopsy of renal masses: sensitivity and negative predictive value stratified by clinical setting and size of masses.

OBJECTIVE: The purpose of our retrospective study was to evaluate the sensitivity and negative predictive value of percutaneous biopsy of renal masses stratified by clinical setting and the size of the mass. MATERIALS AND METHODS: We categorized 115 consecutive percutaneous biopsies of renal masses in 113 patients into four clinical settings and three groups of mass sizes. The sensitivity and negative predictive value were computed (with 95% confidence intervals [CI]) for each clinical setting and for each size group. RESULTS: For all procedures (n = 115), the sensitivity and negative predictive value were 90% (95% CI, 81-95%) and 64% (95% CI, 44-81%), respectively. For patients with a known malignancy who presented with a renal mass (n = 55), the sensitivity and negative predictive value were 90% (95% CI, 78-96%) and 38% (95% CI, 10-74%), respectively. For patients with no known malignancy and suspected unresectable tumor (n = 36), the sensitivity and negative predictive value were 92% (95% CI, 76-98%) and 0%, respectively. For patients with no known malignancy who presented with a cystic mass (n = 16), the sensitivity and negative predictive value were 33% (95% CI, 2-87%) and 87% (95% CI, 58-98%), respectively. For patients who were not surgical candidates with a renal cell carcinoma (n = 8) that was thought to be resectable, both the sensitivity and negative predictive value were 100%. For masses 3 cm and less (n = 31), the sensitivity and negative predictive value were 84% (95% CI, 63-95%) and 60% (95% CI, 27-86%), respectively. For masses between 4 and 6 cm (n = 42), the sensitivity and negative predictive value were 97% (95% CI, 83-100%) and 89% (95% CI, 51-99%), respectively. For masses greater than 6 cm (n = 42), the sensitivity and negative predictive value were 87% (95% CI, 71-95%) and 44% (95% CI, 15-77%), respectively. CONCLUSION: Percutaneous renal mass biopsy has a high sensitivity in three clinical settings: patients with a known malignancy, patients with no known malignancy and suspected unresectable tumor, and nonsurgical patients with a mass suspected to be a resectable renal cell carcinoma. Negative results in small (< or = 3 cm) and large (> 6 cm) masses should be viewed with caution.

Aged↗
PubMed2003

Sonographic features of benign thyroid nodules: interobserver reliability and overlap with malignancy.

OBJECTIVE: To prospectively determine the sonographic findings of nodular hyperplasia of the thyroid, to compare these with reported findings associated with malignancy, and to assess interobserver reliability. METHODS: Seventy thyroid nodules were scanned, and then biopsies of the nodules were performed under sonographic guidance with fine-needle cytologic analysis; in all cases images were reviewed by 2 experienced radiologists without knowledge of clinical outcome. Findings reported associated with malignancy were specifically assessed. Interobserver agreement between the expert and secondary readers for each finding was calculated by the kappa or weighted kappa statistic and the Fisher exact test of independence. RESULTS: There were 68 benign and 2 malignant nodules in a population of 63 female and 7 male patients. The mean benign nodule size was 2.9 cm; 60% were solid; 54% were hypoechoic; 59% were microlobulated or macrolobulated; 47% had central vascularity; 24% contained calcifications; and 82% were elliptical in shape. There was very good interobserver reliability for the presence of calcium (kappa = 0.91) and good agreement for the presence and location of vascularity (kappa = 0.75) and the amount of cystic components (kappa = 0.62; all P < .01). CONCLUSIONS: Sixty-nine percent of benign nodules had at least 1 finding reported previously as associated with malignancy. The interobserver reliability of the sonographic findings was good to very good for 3 of the 5 findings assessed.

Biopsy, Fine-Needle↗
PubMed2003

Fecal incontinence in the postreproductive woman.

Magnetic resonance imaging (MRI) of the pelvic floor specifically to evaluate causes of fecal incontinence is relatively new. Along with physical examination and endoanal ultrasound, recently developed MRI techniques can be used to more accurately diagnose and characterize pelvic floor disorders leading to fecal incontinence. All three compartments of the pelvic floor can be evaluated simultaneously using MRI. During an MRI study, images are rapidly obtained in the sagittal plane at rest and during strain, and in the axial plane at rest. In symptomatic patients, abnormal descent of pelvic viscera is indicative of muscle or fascial weakness. Abnormal descent of pelvic viscera is readily detected on sagittal MR images. Muscle and sphincter tears can also be visualized, although most fascial damage is incurred secondarily. The detailed information gained from an MRI can be used to plan optimal treatment, surgical or otherwise.

Adult↗
PubMed2002

Tumor detection by virtual cystoscopy with color mapping of bladder wall thickness.

PURPOSE: We determine the value of color mapping of bladder wall thickness for detection of tumor as a component of virtual cystoscopy. MATERIALS AND METHODS: A total of 31 subjects with hematuria and/or a history of bladder tumor underwent helical computerized tomography of the pelvis after distention of the bladder with air. Three-dimensional (D) models were constructed, and thickness of the wall was color mapped according to a fixed and validated mm. scale. Axial source images and 3-D models were reviewed and graded for the presence of wall thickening. A comparison was made with findings on conventional cystoscopy in 31 patients and pathological specimen in 13. RESULTS: Compared with conventional cystoscopy, the analysis of axial image yielded a sensitivity of 0.80, specificity 0.90, positive predictive value 0.80 and negative predictive value 0.90 for the presence of tumor. Examination of color mapped 3-D renderings resulted in 0.83, 0.36, 0.42 and 0.71, respectively. CONCLUSIONS: Thin axial computerized tomography of the air distended bladder shows promise as a potential screening tool for bladder cancer. The low specificity of color mapped 3-D renderings makes the technique inappropriate for screening. It may valuable for guiding urologists to additional suspicious sites in a patient with a known tumor.

Aged↗
PubMed2002

Etiology of spontaneous perirenal hemorrhage: a meta-analysis.

PURPOSE: We determine the most common etiology of spontaneous perirenal hemorrhage. MATERIALS AND METHODS: A MEDLINE search of the English language literature from 1985 to 1999 revealed 47 publications and 165 cases of spontaneous renal hemorrhage meeting our study entry criteria. These criteria were presentation of raw data including imaging modality, pathological confirmation (123 cases) or long-term (greater than 2 years) (42) imaging and/or clinical followup and no history of recent trauma, anticoagulant use, dialysis or renal transplant. Meta-analysis was performed using analysis of counts derived from contingency tables and pooled and stratified analysis. RESULTS: Hemorrhage was identified by ultrasound in 56 of 100 cases (56%) and by computerized tomography (CT) in all 135 cases assessed (100%). Etiology was correctly identified with an overall sensitivity and specificity of 0.11 and 0.33 for ultrasound and 0.57 and 0.82 for CT. Angiography in 81 cases revealed active bleeding in 11. The most common etiology of spontaneous renal hemorrhage was benign or malignant neoplasm (101 cases, 61%) with angiomyolipoma being predominant (48) followed closely by renal cell carcinoma (43). Vascular disease was the next most common offender (28 cases, 17%) with polyarteritis nodosa occurring most frequently (20). CONCLUSIONS: The most common cause of spontaneous perirenal hemorrhage is renal neoplasm and approximately 50% of such neoplasms are malignant. CT is the method of choice for evaluation of perirenal hemorrhage, although its sensitivity for detection of underlying etiology is only moderate.

Adolescent↗
PubMed2002

Renal sonography in the intensive care unit: when is it necessary?

OBJECTIVE: To evaluate the efficacy of renal sonography performed in intensive care units on patients with the diagnosis of acute or acute-on-chronic renal failure. METHODS: We reviewed all renal sonograms performed in our institution during 1 year on critically ill patients for evaluation of renal failure. Renal failure was defined as a serum creatinine level greater than 1.5 mg/dL or an increase of greater than 20% from the baseline creatinine level. Exclusion criteria included patient age younger than 18 years and signs or symptoms of obstructive uropathy. Using the electronic medical record, we recorded patient age, sex, blood urea nitrogen level, serum creatinine level, blood urea nitrogen-creatinine ratio, and clinical indication for intensive care unit admission. Sonographic reports were reviewed for the presence or absence of hydronephrosis. The total cost of these examinations was estimated with the use of Medicare reimbursement rates for 2000. RESULTS: One hundred five renal sonographic examinations were performed on 104 patients meeting all inclusion criteria. Only 1 study had positive results for hydronephrosis, which was graded as mild. Incidental findings not immediately affecting patient care and including ascites and simple renal cysts were identified in 91 patients. The estimated total cost of the examinations was $13,350.75. CONCLUSIONS: In critically ill patients with acute renal failure and no physical findings suggesting obstructive uropathy, renal sonography to evaluate for hydronephrosis is probably not indicated. This holds true regardless of patient age, sex, medical or surgical disposition, and blood urea nitrogen-creatinine ratio.

Acute Kidney Injury↗
PubMedDate not supplied

Practical MR imaging of female pelvic floor weakness.

Pelvic floor weakness is common in middle-aged and elderly parous women and is often associated with stress incontinence, uterine prolapse, constipation, and incomplete defecation. Most patients with incontinence and minimal pelvic floor weakness can be treated based on physical examination and basic urodynamic findings. However, in women with symptoms of multicompartment involvement for whom a complex repair is planned or who have undergone previous repairs, magnetic resonance (MR) imaging can be a useful preoperative planning tool. The MR imaging evaluation is performed with the patient in the supine position, without contrast agents, and within 15 minutes. A multicoil array and a rapid half-Fourier T2-weighted imaging sequence are used to obtain sagittal images while the patient is at rest and during pelvic strain, followed by axial images. On these images, the radiologist identifies the pubococcygeal line (which represents the level of the pelvic floor), the H and M lines (which are helpful for confirming pelvic floor laxity), and the angle of the levator plate with the pubococcygeal line (which is helpful for identifying small bowel prolapse). In the appropriate patient, MR images provide relatively easy three-dimensional conceptualization of the pelvic floor and can significantly influence treatment planning.

Adult↗