Biomedical subjects
Publications and source records attributed to Fergus V Coakley.
OBJECTIVE: Our aim was to determine the supplemental value of MRI in fetal abdominal disease detected on prenatal sonography. CONCLUSION: Our preliminary results suggest the primary supplemental value of MRI relative to sonography in fetal abdominal disease lies in improved tissue characterization rather than in improved anatomic characterization.
OBJECTIVE: The purpose of this article is to describe the appearance and causes of inferior vena cava (IVC) filling defects, how such findings may be accurately characterized, and the clinical significance of IVC filling defects. Filling defects in the IVC observed at MDCT and MRI may be a result of flow artifacts, anatomic variants, or bland or malignant thrombus. CONCLUSION: Familiarity with anatomy and flow effects is critical for distinguishing true from false filling defects in the IVC. Delayed imaging after administration of IV contrast material and dedicated MRI sequences may be helpful for further characterization of such findings. Once a true filling defect of the IVC is established, identification of the cause, whether benign or malignant, and extent will guide clinical treatment.
PURPOSE: To retrospectively determine the prognostic importance of small hypoattenuating hepatic lesions at contrast material-enhanced computed tomography (CT) in patients with breast cancer. MATERIALS AND METHODS: This retrospective study was approved by the committee on human research. Written informed consent was not required. The authors retrospectively identified 153 patients with breast cancer who underwent serial abdominal CT and who did not have definite liver metastases present at initial CT. The mean age was 56 years (age range, 27-93 years). Two readers independently recorded the presence, size, and number of small (15 mm or less in diameter) hypoattenuating hepatic lesions at initial CT. Another reader independently recorded the presence or absence of definite hepatic metastases at final CT. The association between the presence, size, and number of small hypoattenuating hepatic lesions at initial CT and the subsequent development of metastases was analyzed by using Kaplan-Meier analysis. RESULTS: One or more small hypoattenuating hepatic lesions were seen at initial CT in 54 of 153 patients (35%). After a median follow-up of 584 days (range, 16-1827 days), definite hepatic metastases developed in 43 of 153 patients (28%), including 15 of 54 patients (28%) with hypoattenuating lesions at initial CT and 28 of 99 patients (28%) without hypoattenuating lesions at initial CT. Findings from the Kaplan-Meier analysis showed no association between the presence (P = .56), size (P = .55), or number (P = .30) of small hypoattenuating hepatic lesions at initial CT and the subsequent development of hepatic metastases. CONCLUSION: In patients with breast cancer who do not have definite hepatic metastases at initial examination, there is no evidence that small hypoattenuating hepatic lesions seen at initial CT contribute to an increased risk of subsequently developing hepatic metastases.
PURPOSE: To retrospectively determine a biometric algorithm for calculating relative lung volume in fetuses with normal lungs and of a wide range of gestational ages by using proved independent variables and to retrospectively investigate the use of this algorithm in fetuses with pulmonary hypoplasia. MATERIALS AND METHODS: Total lung volume (TLV) was measured by using planimetry on single-shot rapid acquisition with relaxation enhancement magnetic resonance (MR) images obtained in 91 fetuses with ultrasonographically (US) normal chests and 28 fetuses with US-determined pulmonary hypoplasia. All fetuses were aged between 18 and 38 weeks gestation. Analysis of covariance was used to identify parameters that were not different between the fetuses with US-determined normal and those with US-determined abnormal chests, and these variables were used to construct an algorithm for calculating predicted lung volume. The relative lung volume-that is, the observed lung volume expressed as a percentage of the predicted lung volume-was then calculated in fetuses with pulmonary hypoplasia. RESULTS: There was no significant difference in mean maternal or gestational age between the two fetus groups. Stepwise regression analysis was used to generate the following equation for predicting fetal lung volume on the basis of independent biometric indexes, with a correlation coefficient of 0.93: TLV = (0.52 . LV) + (0.33 . BD) - (0.06 . FL) - 13.7, with TLV and liver volume (LV) in milliliters and biparietal diameter (BD) and femoral length (FL) in centimeters. In the fetuses with normal chests, relative lung volume varied between 51% and 134%. In the fetuses with pulmonary hypoplasia, relative lung volume varied between 6% and 70%. CONCLUSION: The predicted lung volume in fetuses of a wide range of gestational ages can be calculated with a high degree of accuracy, enabling prenatal MR imaging lung volumetry in which relative lung volume is used to quantify fetal pulmonary hypoplasia.
PURPOSE: To evaluate endorectal magnetic resonance (MR) imaging and MR spectroscopic imaging for the depiction of locally recurrent prostate cancer after external beam radiation therapy. MATERIALS AND METHODS: Endorectal MR imaging and MR spectroscopic imaging were performed in 21 patients with biochemical failure after external beam radiation therapy for prostate cancer. Two readers independently and retrospectively reviewed MR images and rated the likelihood of recurrent tumor on a five-point scale. Spectroscopic voxels were considered suspicious for malignancy if the choline level was elevated and citrate was absent. Receiver operating characteristic curve analysis was used to assess cancer detection in each side of the prostate with endorectal MR imaging and spectroscopic imaging at different thresholds based on the scores assigned by the two readers and on the number of suspicious voxels in each hemiprostate, respectively. The presence or absence of cancer at subsequent transrectal biopsy was used as the standard of reference. RESULTS: Biopsy demonstrated locally recurrent prostate cancer in nine hemiprostates in six patients. The area under the receiver operating characteristic curve for the detection of locally recurrent cancer with MR imaging was 0.49 and 0.51 for readers 1 and 2, respectively. By using the number of suspicious voxels to define different diagnostic thresholds, the area under the receiver operating characteristic curve for MR spectroscopic imaging was significantly (P < .005) higher, at 0.81. In particular, the presence of three or more suspicious voxels in a hemiprostate showed a sensitivity and specificity of 89% and 82%, respectively, for the diagnosis of local recurrence. Seven hemiprostates demonstrated complete metabolic atrophy at spectroscopic imaging and only postirradiation atrophy at biopsy. CONCLUSION: Preliminary data suggest that MR spectroscopic imaging, but not endorectal MR imaging, may be of value for the depiction of locally recurrent prostate cancer after radiation therapy.
BACKGROUND: Because the recovery of erectile function and the avoidance of positive surgical margins are important but competing outcomes, the decision to preserve or resect a neurovascular bundle (NVB) during radical prostatectomy (RP) should be based on the most accurate information concerning the location and extent of the tumor. In the current study, the authors determined the incremental value of endorectal magnetic resonance imaging (eMRI) in making this decision. METHODS: eMRI was performed in 135 patients preoperatively. For each NVB, tumor extension to the NVB and the need for NVB resection was judged by a surgeon on a scale from 1 (definite preservation) to 5 (definite resection) before and after reviewing eMRI with a radiologist. Histopathologic findings were used as the standard of reference. The value of eMRI was assessed using binormal receiver operating characteristic (ROC) analysis adjusted for multiple observations per patient, and a mixed effects ordinal regression model was used for risk stratification. RESULTS: Histopathologic examination determined that NVB resection was warranted in 44 of 270 NVBs (16%) because of posterolateral extracapsular extension (n = 29), positive surgical margins (n = 7), or both (n = 8). The areas under the ROC curves (AUC) were 0.741 for pre-MRI and 0.832 for post-MRI surgical planning (P < 0.01). MRI findings suggested altering the surgical plan in 39% of NVBs (106 of 270 NVBs). When the surgeon judged that the NVB resection was definitely not necessary (165 NVBs), MRI confirmed that decision in 138 NVBs (84%); the concordant decision was correct in 96% of the cases (133 of 138 NVBs). In 36 high-risk patients (> or = 75% probability of extracapsular extension), MRI findings changed the surgical plan for 28 NVBs (78%); the change was found to be appropriate in 26 cases (93%). CONCLUSIONS: MRI was found to significantly improve the surgeon's decision to preserve or resect the NVB during radical prostatectomy.
Evaluation of the biliary tract after liver transplantation, particularly when a Roux-en-Y hepatojejunostomy precludes endoscopic retrograde cholangiography, may be challenging. We present five cases of suspected biliary obstruction after liver transplantation in which multidetector-row computed tomography (CT) cholangiography was used. In conclusion, it was determined that multidetector-row CT cholangiography may be a useful modality for demonstrating patent biliary-enteric anastomoses and excluding flow-limiting biliary anastomotic strictures.
The primary indication for prostate MR and MR spectroscopic imaging is evaluating men with newly diagnosed prostate cancer who are deciding whether to undergo surgery or radiotherapy. Other applications of MR and MR spectroscopic imaging in prostate cancer are not defined fully. Areas of research include volumetric localization of prostate cancer, in vivo MR spectroscopic imaging at high field strength, in vitro MR spectroscopic imaging at very high field strength, novel spectroscopic markers of malignancy,and interventional MR guidance of biopsy and therapy. MR spectroscopic imaging remains a relatively novel technique, and successful implementation is demanding. Nonetheless, only MR and MR spectroscopic imaging allow structural and metabolic evaluation of prostate cancer location, aggressiveness, and stage, and MR imaging provides clinically and therapeutically relevant information on prostatic and periprostatic anatomy.
The imaging appearances of surgical materials in the postoperative abdomen and pelvis can be confusing and difficult to interpret. With the increasing complexity of surgical procedures and more frequent use of postoperative imaging, the radiologist needs to be familiar with the imaging characteristics of a variety of intentionally and unintentionally placed surgical materials and devices. In addition, they must be differentiated from postoperative complications such as hematoma or abscess.
PURPOSE: To determine the effect of digital rectal examination findings, sextant biopsy results, and prostate-specific antigen (PSA) levels on reader accuracy in the localization of prostate cancer with endorectal magnetic resonance (MR) imaging and MR spectroscopic imaging. MATERIALS AND METHODS: This was a retrospective study of 37 patients (mean age, 57 years) with biopsy-proved prostate cancer. Transverse T1-weighted, transverse high-spatial-resolution, and coronal T2-weighted MR images and MR spectroscopic images were obtained. Two independent readers, unaware of clinical data, recorded the size and location of suspicious peripheral zone tumor nodules on a standardized diagram of the prostate. Readers also recorded their degree of diagnostic confidence for each nodule on a five-point scale. Both readers repeated this interpretation with knowledge of rectal examination findings, sextant biopsy results, and PSA level. Step-section histopathologic findings were the reference standard. Logistic regression analysis with generalized estimating equations was used to correlate tumor detection with clinical data, and alternative free-response receiver operating characteristic (AFROC) curve analysis was used to examine the overall effect of clinical data on all positive results. RESULTS: Fifty-one peripheral zone tumor nodules were identified at histopathologic evaluation. Logistic regression analysis showed awareness of clinical data significantly improved tumor detection rate (P <.02) from 15 to 19 nodules for reader 1 and from 13 to 19 nodules for reader 2 (27%-37% overall) by using both size and location criteria. AFROC analysis showed no significant change in overall reader performance because there was an associated increase in the number of false-positive findings with awareness of clinical data, from 11 to 21 for reader 1 and from 16 to 25 for reader 2. CONCLUSION: Awareness of clinical data significantly improves reader detection of prostate cancer nodules with endorectal MR imaging and MR spectroscopic imaging, but there is no overall change in reader accuracy, because of an associated increase in false-positive findings. A stricter definition of a true-positive result is associated with reduced sensitivity for prostate cancer nodule detection.
PURPOSE: To determine the prevalence and morphologic associations of precaval right renal arteries at spiral computed tomography (CT). MATERIALS AND METHODS: The authors retrospectively reviewed 186 arterial phase contrast material-enhanced spiral CT scans of the abdomen (5.0-mm section thickness in 97 scans, 2.5 mm in 89 scans) obtained during a 2-year period to identify patients with precaval right renal arteries. During routine interpretation of CT scans at daily readout, the authors prospectively identified 39 additional patients with precaval right renal arteries. All cases were evaluated for anatomic variants and associated clinical findings. Fisher exact analysis and chi2 analysis were performed to compare the frequency of anatomic variants between patients with and those without precaval renal arteries. RESULTS: Nine of 186 patients had precaval right renal arteries, for a prevalence of 5%. In the 48 patients with precaval renal arteries, 52 precaval arteries were found, of which 48 were accessory and four were dominant. Fourteen patients had right pelviectasis to the level of the precaval artery, and three of these had a clinical diagnosis of right ureteropelvic junction obstruction. Eighteen (35%) of the 52 precaval renal arteries arose from the anterior aspect of the aorta (within 30 degrees of the midline). The lower pole of the right kidney was rotated anteriorly in two (22%) of nine and 13 (33%) of 39 patients with precaval renal arteries in the retrospective and prospective groups, respectively, compared with four (2%) of 177 patients without precaval arteries (P <.05 and P <.001, respectively). CONCLUSION: On the basis of these results, precaval right renal arteries appear to be more common than previously reported. Anterior rotation of the lower pole of the right kidney should prompt a search for precaval renal arteries.
PURPOSE: To compare biliary tract depiction in living potential liver donors at conventional magnetic resonance (MR), mangafodipir trisodium-enhanced excretory MR, and multi-detector row computed tomographic (CT) cholangiography. MATERIALS AND METHODS: Eight living potential liver donors underwent iodipamide meglumine-enhanced CT cholangiography. Eight different potential liver donors then underwent conventional MR cholangiography and mangafodipir trisodium-enhanced excretory MR cholangiography. Two readers independently scored all first-, second-, and third-order biliary branches with a four-point scale from 0 (not seen) to 3 (excellent visualization). Interobserver agreement was calculated by using the weighted kappa statistic. Scores were compared between imaging modalities by using generalized estimating equations. Imaging findings of second-order biliary tract anatomy were compared with intraoperative findings for nine patients. RESULTS: Interobserver agreement for overall biliary tract visualization was good for CT, conventional MR, and excretory MR cholangiography (with weighted kappa values of 0.76, 0.66, and 0.79, respectively). The mean second-order biliary branch visualization scores for readers 1 and 2, respectively, were significantly higher at CT cholangiography (2.81 and 2.75) than at conventional MR (1.84 and 1.75, P <.001), excretory MR (2.00 and 2.06, P <.001), and combined conventional and excretory MR cholangiography (2.31 and 2.25, P <.01). At CT, conventional MR, and excretory MR cholangiography, respectively, second-order biliary branching anatomy was discernible in eight, five, and seven patients, with second-order biliary branch variants seen in three, two, and two patients. Surgical findings confirmed the pattern of second-order biliary branching seen at CT in five patients, that seen at conventional MR imaging in one patient, and that seen at excretory MR cholangiography in three patients. At surgery, one case of variant biliary anatomy was found to have been missed at CT cholangiography. CONCLUSION: In living potential liver donors, CT cholangiography enables significantly better biliary tract visualization than conventional or excretory MR cholangiography either alone or in combination.
PURPOSE: To investigate the accuracy and interobserver variability of a standardized evaluation system for endorectal three-dimensional (3D) magnetic resonance (MR) spectroscopic imaging of the prostate. MATERIALS AND METHODS: The human research committee approved the study, and all patients provided written informed consent. Endorectal MR imaging and MR spectroscopic imaging were performed in 37 patients before they underwent radical prostatectomy. For the 22 patients with good or excellent MR spectroscopic imaging data, step-section histopathologic tumor maps were used to identify spectroscopic voxels of unequivocally benign (n = 306) or malignant (n = 81) peripheral zone tissue. Two independent spectroscopists, unaware of all other findings, scored the spectra of the selected voxels by using a scale of 1 (benign) to 5 (malignant) that was based on standardized metabolic criteria. Descriptive statistical, receiver operating characteristics (ROC), and kappa statistical analyses of the data obtained by both readers were performed by using two definitions of cancer: one based on a voxel score of 3-5 and the other based on a score of 4 or 5. RESULTS: The scoring system had good accuracy (74.2%-85.0%) in the differentiation between benign and malignant tissue voxels, with areas under the ROC curve of 0.89 for reader 1 and 0.87 for reader 2. Specificities of 84.6% and 89.3% were achieved when a voxel score of 4 or 5 was used to identify cancer, and sensitivities of 90% and 93% were achieved when a score of 3-5 was used to identify cancer. Readers demonstrated excellent interobserver agreement (kappa values, 0.79 and 0.80). CONCLUSION: The good accuracy and excellent interobserver agreement achieved by using the standardized five-point scale to interpret peripheral zone metabolism demonstrate the potential effectiveness of using metabolic information to identify prostate cancer, and the clinical usefulness of this system warrants testing in prospective clinical trials of MR imaging combined with MR spectroscopic imaging.
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OBJECTIVE: We undertook this study to determine the causes of peritoneal calcification seen on CT and to investigate which CT features distinguish benign from malignant peritoneal calcification. MATERIALS AND METHODS: Seventeen patients with peritoneal calcification were identified through retrospective review of reports from 74765 abdominopelvic CT examinations performed during a 7-year period. We determined the cause of peritoneal calcification by examining medical and histopathologic records. Calcification morphology was classified as nodular or sheetlike on the basis of the consensus interpretation by two independent radiologists. The radiologists also recorded the presence or absence of associated soft-tissue components or lymph node calcification. The association between the CT findings and the cause of calcification was assessed using chi-square analysis. RESULTS: Peritoneal calcification was due to peritoneal dialysis (n = 4), prior peritonitis (n = 3), cryptogenic origin (n = 1), or peritoneal spread of ovarian carcinoma (n = 9). Sheet-like calcification was more common in patients with benign calcification (seven of eight patients) than in those with malignant calcification (two of nine patients, p < 0.05). Nodal calcification was seen only in patients with malignant calcification (five of nine patients vs none of eight, p < 0.05). CONCLUSION: Common causes of peritoneal calcification are dialysis, prior peritonitis, or ovarian cancer; sheetlike calcification indicates a benign cause, whereas associated lymph node calcification strongly suggests malignancy.
OBJECTIVE: Our aim was to determine whether parallel imaging and diffusion tensor imaging affect the measurement of apparent diffusion coefficient (ADC) during diffusion-weighted MRI of the liver in healthy volunteers. SUBJECTS AND METHODS: We performed breath-hold single-shot echo-planar diffusion-weighted MRI of the liver in 10 healthy volunteers using conventional diffusion, conventional diffusion with parallel imaging, and diffusion tensor with parallel imaging sequences. TE values for the three sequences were 83, 74, and 63, respectively. Liver signal intensity was measured on all sequences and normalized to the SD of the measurement. Hepatic ADC was calculated by acquiring all sequences with b values of 0 and 500 sec/mm(2). RESULTS: The normalized liver signal intensity was higher on diffusion tensor with parallel imaging and conventional diffusion with parallel imaging than on conventional diffusion without parallel imaging for a b value of 500 sec/mm(2) (13.0 and 10.1 vs 9.1, respectively; p < 0.03) and for a b value of 0 sec/mm(2) (9.0 and 7.6 vs 6.9, respectively; without reaching a significant difference, p = 0.12). Hepatic ADC was not significantly different between sequences (p = 0.16). CONCLUSION: Higher signal intensity can be obtained when using parallel imaging and diffusion tensor imaging during diffusion-weighted MRI of the liver without compromising hepatic ADC measurement.
OBJECTIVE: We sought to describe the role of opposed-phase MRI in the diagnosis of nodular fatty sparing in the liver. CONCLUSION: Nodular fatty sparing of the liver displays characteristic findings on opposed-phase MRI. Because the lesion may otherwise mimic a hepatic tumor, knowledge of these findings may prevent unnecessary biopsy or inappropriate treatment.
OBJECTIVE: Our aim was to determine the effect of prior transrectal biopsy on endorectal MRI and MR spectroscopic imaging findings in patients with organ-confined prostate cancer. MATERIALS AND METHODS: Endorectal MRI and MR spectroscopic imaging were performed in 43 patients with biopsy-proven prostate cancer before radical prostatectomy confirming organ-confined disease. For each sextant, two independent reviewers scored the degree of hemorrhage on a scale from 1 to 5 and recorded the presence or absence of capsular irregularity. A spectroscopist recorded the number of spectrally degraded voxels in the peripheral zone. The outcome variables of capsular irregularity and spectral degradation were correlated with the predictor variables of time from biopsy and degree of hemorrhage after biopsy. RESULTS: Capsular irregularity was unrelated to time from biopsy or to degree of hemorrhage. Spectral degradation was inversely related to time from biopsy (p < 0.01); the mean percentage of degraded peripheral zone voxels was 18.5% within 8 weeks of biopsy compared with 7% after 8 weeks. Spectral degradation was unrelated to the degree of hemorrhage. CONCLUSION: In organ-confined prostate cancer, capsular irregularity can be seen at any time after biopsy and is independent of the degree of hemorrhage, whereas spectral degradation is seen predominantly in the first 8 weeks after biopsy. MRI staging criteria and guidelines for scheduling studies after biopsy may require appropriate modification.