PubMed Health⌕ Search

Biomedical subjects

Peter F Hahn

Publications and source records attributed to Peter F Hahn.

At least 19 recordsLinked to original sources
PubMed2007

16-MDCT angiography in living kidney donors at various tube potentials: impact on image quality and radiation dose.

OBJECTIVE: The objective of our study was to compare the performance of 16-MDCT angiography at various peak kilovoltage (kVp) settings and the impact of the different settings on image quality and on radiation dose in adult kidney donors. MATERIALS AND METHODS: Sixty-two renal donors (32 men, 30 women) who underwent 16-MDCT were divided into three groups: 18 subjects were studied at 140 kVp (group A); 20, at 120 kVp (group B); and 24, at 100 kVp (group C). Other constant scanning parameters were as follows: detector collimation, 0.625 mm; table feed, 9.375 mm/rotation; gantry rotation time, 500 milliseconds; and automatic current tube modulation (ATCM) using a noise index of 15. A total of 135-140 mL of iodinated contrast material (300 mg I/mL) was administered at 5 mL/s via an 18-gauge cannula, and arterial phase scanning was initiated using a bolus-tracking technique. Two observers evaluated image quality of the axial and 3D images and the visibility of branch order in the superior mesenteric artery (SMA) and renal arteries. Attenuation (in Hounsfield units [H]) in the aorta, SMA, and main renal artery was also measured by placing a region of interest. Radiation dose measurements were based on the scanner-generated CT dose index volume (CTDI(vol)). Each parameter tested was compared among the three groups using a nonparametric analysis of variance test, and a p value of 0.05 was considered significant. RESULTS: Differences in the quality of the axial images existed between groups A and C (p < 0.001) and between groups B and C (p < 0.01); the image quality of the 3D images and the visibility of branch order in the SMA and renal arteries were comparable for all groups. The difference in mean attenuation of the aorta, SMA, and renal arteries was significant between groups A and C (p < 0.001) and between groups B and C (p < 0.01). All groups had 100% diagnostic accuracy in identifying the number of renal arteries on the side of nephrectomy. The mean radiation dose in CTDI(vol) was 25 +/- 3 mGy at 140 kVp, 17 +/- 4 mGy at 120 kVp, and 12 +/- 3 mGy at 100 kVp (p < 0.001). CONCLUSION: Our initial observations suggest that the image quality of 16-MDCT angiography performed at 120 kVp is similar to that of CT angiography (CTA) performed at 140 kVp in adult kidney donors but with a significant radiation dose reduction. CTA at 100 kVp results in higher image noise but provides diagnostically acceptable images with significant radiation dose reduction compared with CTA at 120 or 140 kVp.

Adult↗
PubMed2007

Uterine smooth-muscle tumors with unusual growth patterns: imaging with pathologic correlation.

OBJECTIVE: This essay illustrates the salient features of variant smooth-muscle tumors on multiple imaging techniques with correlative pathology. We describe how recognition of these features allows the radiologist to distinguish a uterine leiomyoma variant from the classic fibroid or a leiomyosarcoma. Finally, we highlight the role of the radiologist in triaging these patients to surgical versus medical management and in surgical planning. CONCLUSION: Parasitic leiomyoma, intravenous leiomyomatosis, disseminated peritoneal leiomyomatosis, and benign metastasizing leiomyoma show key features on multiple imaging techniques that correlate with pathology findings. In the appropriate clinical setting, the radiologist should include these unusual lesions in the broader differential diagnosis of smooth-muscle tumors and, in certain cases, aid in surgical planning.

Adult↗
PubMed2006

Adrenal lesions: attenuation measurement differences between CT scanners.

PURPOSE: To retrospectively compare unenhanced computed tomographic scans of the same adrenal lesion obtained with two different manufacturers' multidetector scanners to assess whether there are differences in attenuation measurements. MATERIALS AND METHODS: The study was approved by the local ethical committee, which waived patient consent, and was conducted in compliance with HIPAA. Electronic searching revealed patients with adrenal nodules scanned with both a Siemens 16-detector row scanner and one of eight GE Medical Systems multi-detector row scanners between January 2000 and September 2004 without the use of intravenous contrast material. Lesions were characterized by using histologic findings, fat content, or size stability. Size stability for 6 months was required unless both scans were obtained within 21 days of each other. Two radiologists independently measured lesion attenuation for regression analysis. Lesions considered benign (< or = 10 HU) on one scan and indeterminate (> 10 HU) on the other were separately analyzed, and technical parameters of scanning were compared. RESULTS: There were 47 patients (27 men, 20 women; age range, 40-86 years; mean age, 64 years) with four metastases, 42 adenomas, and one myelolipoma (long-axis length, 10-85 mm; mean, 24 mm). GE scans were obtained with four-detector row scanners (n = 32), an eight-detector row scanner (n = 2), and 16-detector row scanners (n = 13). Correlation between the two readers was 0.99 for both Siemens and GE scan attenuation measurements. The slope of regression lines for both readers plotting GE attenuation (y-axis) against Siemens attenuation (x-axis) was less than 1, which indicated a slight but statistically significant tendency for GE scans to have lower attenuations than do Siemens scans. For both readers, there were more lesions indeterminate (> 10 HU) on Siemens scans but benign (< or = 10 HU) on GE scans than the reverse (McNemar test, P < .02 for reader 1, not significant for reader 2). Average Siemens and GE scan technical parameters were similar. CONCLUSION: There are only slight differences in attenuation of adrenal nodules measured on scans obtained with different scanners.

Adrenal Gland Neoplasms↗
PubMed2006

Effect of obesity on image quality: fifteen-year longitudinal study for evaluation of dictated radiology reports.

PURPOSE: To retrospectively assess the effect of obesity on image quality, as determined from dictated radiology reports filed between 1989 and 2003. MATERIALS AND METHODS: Institutional review board approval was obtained for this HIPAA-compliant study; informed consent was not required. Electronic records were searched for radiology reports with the phrase "limited due to body habitus" (hereafter, "habitus limited") filed between 1989 and 2003; reports were retrospectively reviewed. Habitus limited was qualified as the search phrase by auditing radiologic images and patient weights. Trends in the number of habitus-limited reports were calculated for each year, and linear regression analysis was performed. The number of habitus-limited reports was also compared between modalities within a year and within each modality across 15 years. The trend was correlated with the prevalence of obesity in Massachusetts by using the Pearson correlation coefficient. RESULTS: There was a significant difference (P < .001) between the weight of patients with habitus-limited reports and the weight of patients with reports that were not habitus limited. Overall, 7778 (0.15%) of 5 253 014 reports were habitus limited. Between 1989 and 2003, there was a linear increase of 0.010% per year (95% confidence interval: 0.007%, 0.013%; P < .001). There was a positive correlation between the increased number of habitus-limited reports and the increased prevalence of obese individuals in Massachusetts between 1991 and 2001. The modality most commonly associated with habitus-limited reports was abdominal ultrasonography. CONCLUSION: There was a small but progressive increase in the number of habitus-limited radiology reports between 1989 and 2003.

Adolescent↗
PubMed2006

Pancreatic cysts 3 cm or smaller: how aggressive should treatment be?

PURPOSE: To retrospectively determine the frequency of malignancy in small (< or =3 cm) pancreatic cysts, to evaluate whether cyst morphologic features can help predict the presence of malignancy, and to determine the natural history of small pancreatic cysts at follow-up imaging. MATERIALS AND METHODS: Institutional review board approval was obtained; informed patient consent was not required. By means of a computerized search, 510 patients with pancreatic cysts that had been detected at computed tomography (CT) or magnetic resonance (MR) imaging were identified. Cysts that were 3 cm or smaller at surgery or endoscopic ultrasonography (US)-guided cyst fluid aspiration and biopsy were included. Eighty-six patients-31 men and 55 women aged 24-89 years-fulfilled the criteria. Patients underwent surgery or were monitored with endoscopic US-guided cyst fluid analysis, cytologic analysis, and follow-up imaging. Imaging findings were compared with surgical and pathology records and with endoscopic US features. Positive predictive values (PPVs) for benignity and malignancy were calculated on the basis of cyst size and absence or presence of septa in the cysts. RESULTS: Forty-eight patients underwent surgery, and 38 were treated nonsurgically. Seventy-five patients had benign cysts; eight, borderline (malignant) neoplasms; and three, carcinoma in situ lesions. The PPV of small pancreatic cysts for prediction of benignity was 87% (75 of 86 patients). Thirty-six patients had unilocular cysts (35 with benign lesions, one with borderline neoplasm). The PPV of unilocular cysts for prediction of benignity was 97% (35 of 36 patients). Fifty patients had septated cysts; seven of these patients had borderline neoplasms, and three had carcinoma in situ lesions. For prediction of malignancy in small cysts, the PPV of septa was 20% (10 of 50 patients), which was significantly higher than the 3% (one of 36 patients) PPV of unilocular cysts (P = .042). No significant changes in cyst morphologic features were seen in patients who were followed up with imaging for a mean period of 21.8 months. CONCLUSION: The majority (n = 75) of small pancreatic cysts were benign. Thirty-six cysts were unilocular, and virtually all of these (n = 35) were benign. The presence of septa was associated with borderline or in situ malignancy in 20% (10 of 50) of cases.

Adult↗
PubMed2006

Intraductal papillary mucinous neoplasm of pancreas: multi-detector row CT with 2D curved reformations--correlation with MRCP.

PURPOSE: To retrospectively compare accuracy of multi-detector row computed tomography (CT), combined with two-dimensional (2D) curved reformations, and that of magnetic resonance (MR) cholangiopancreatography (MRCP) for characterization of intraductal papillary mucinous neoplasm (IPMN) as malignant, with pathologic examination as reference standard. MATERIALS AND METHODS: Institutional review board approval was obtained, informed consent was waived, and study was HIPAA compliant. Twenty-five patients (12 women, 13 men; age range, 44-88 years) with pathologically proved IPMN were examined with dual-phase CT with 1.25-mm-thick sections for pancreatic phase; 2D curved reformations along main pancreatic duct (MPD) were generated. T2-weighted MRCP included thick- and thin-slab single-shot fast spin-echo imaging and transverse fast spin-echo imaging. Two radiologists, blinded to surgical and pathologic findings, evaluated images for lesion location, septa, mural nodules, communication with MPD, extent and diameter of MPD dilatation, calcifications, and vascular encasement. Malignancy was suspected when one of the following was present: MPD diameter larger than 10 mm, mural nodules, vascular encasement, peripancreatic lymphadenopathy, or metastases. Sensitivity and specificity values for prediction of malignancy were calculated for CT and MRCP. Interobserver variability was determined (kappa analysis). RESULTS: Excellent correlation between modalities was observed. Cyst communication was seen in 20 and 21 of 24 branch pancreatic duct (BPD) IPMNs with CT and MRCP, respectively. Sensitivity, specificity, and accuracy for detection of malignancy were 70%, 87%, and 76% (CT) and 70%, 92%, and 80% (MRCP), respectively. Interobserver agreement was good to perfect for both readers in all comparisons (overall, kappa = 0.70-1.00). CONCLUSION: CT combined with 2D curved reformation can provide imaging details of IPMN, including communication of BPD IPMN with MPD, that are almost equivalent to those provided at MRCP. Presence of mural nodules, dilated MPD (>10-mm diameter), or thick septa at CT or MRCP may be used as independent predictors of malignancy.

Adenocarcinoma, Mucinous↗
PubMed2006

Tagging-based, electronically cleansed CT colonography: evaluation of patient comfort and image readability.

PURPOSE: To prospectively compare the homogeneity, adequacy, and patient acceptance of nonionic iodine-based regimens with those of a barium-based regimen for computed tomographic (CT) colonography with electronic subtraction cleansing. MATERIALS AND METHODS: After institutional review board approval and informed consent were obtained, 68 subjects (41 men (60%) men, 27 (40%) women; mean age, 60 years +/- 6 [standard deviation]) with average or moderate risk factors for development of colorectal carcinoma were recruited and placed into three study groups. Group 1 (n = 25) ingested 150-mL aliquots of 2% barium sulfate suspension with meals and snacks for 48 hours prior to imaging, without other diet modification or a cathartic. Group 2 (n = 21) ingested 10-mL aliquots of nonionic iodinated contrast material (iopromide) with a concentration of 300 mg per milliliter with meals and snacks for 2 days before imaging, without diet modification or a cathartic. Group 3 (n = 22) ingested nonionic iodinated contrast material (iohexol) with a concentration of 300 mg per milliliter with meals and snacks for 2 days before imaging and ingested 34 g of magnesium citrate the evening prior to imaging. CT colonography was also performed on 10 control subjects who ingested polyethylene glycol electrolyte solution prior to imaging. Subjective and numerical measures of bowel preparation quality, homogeneity, and patient comfort among the noncathartic and cathartic cohorts were compared with nonparametric analysis of variance, the Fisher exact test, and the F test, as appropriate. The study was HIPAA compliant. RESULTS: Study subjects who received tagging preparations reported significantly improved discomfort scores when compared with those of the control subjects (P < .05, each comparison). There was no significant difference in discomfort scores among groups 1, 2, and 3. For each reader, scores of subtracted image readability were highest for group 3. Dichotomized rates of preparation "success" were also greatest for group 3. CONCLUSION: In this series, the patient discomfort scores were significantly improved with tagging preparations for CT colonography. Nonionic iodinated contrast material in conjunction with a hyperosmotic laxative (magnesium citrate) was associated with the best subjective and numerical indices of readability.

Aged↗
PubMed2006

Ferumoxtran-10-enhanced MR lymphangiography: does contrast-enhanced imaging alone suffice for accurate lymph node characterization?

OBJECTIVE: Ferumoxtran-10 is a lymphotropic MR contrast agent that is currently under investigation. It has been shown to be effective in staging lymph nodes of patients with various primary malignancies. The current technique with ferumoxtran-10 involves imaging before and 24 hr after contrast administration. The purpose of this study was to evaluate the accuracy of ferumoxtran-10-enhanced images alone in characterizing lymph nodes for oncologic staging 24 hr after contrast enhancement. MATERIALS AND METHODS: Seventy-seven patients (58 men, 19 women) with proven primary cancer (bladder [n = 20], breast [n = 10], endometrial [n = 1], renal [n = 3], penile [n = 4], prostate [n = 31], rectal [n = 1], testicular [n = 5], and ureteral [n = 2]) who were scheduled for surgical lymph node dissection were enrolled in the study. In these patients, 169 lymph nodes (mean size, 11.2 mm) were evaluated on T2*-weighted gradient-refocused echo MRI at l.5 T both before and 24-36 hr after the IV administration of ferumoxtran-10 (2.6 mg Fe/kg). Two blinded reviewers with differing levels of interpreting experience separately performed qualitative image evaluation. A 6-point scale was used to characterize lymph nodes on contrast-enhanced images alone and on combined unenhanced and contrast-enhanced images. Receiver operating characteristic (ROC) analysis was performed separately for both reviewers. RESULTS: Of the 169 lymph nodes evaluated, 55 were benign and 114 malignant by histopathologic analysis. The results of the ROC analysis comparing contrast-enhanced images ([A(z) = area under ROC curve] reviewer 1, A(z) = 0.92; reviewer 2, A(z) = 0.94) alone with combined unenhanced and contrast-enhanced images (reviewer 1, A(z) = 0.94; reviewer 2, A(z) = 0.93) showed a statistically significant difference (p = 0.01) for reviewer 1 but no difference for reviewer 2 (p = 0.88). Reviewer 2 was more experienced in interpreting ferumoxtran-10-enhanced images than reviewer 1. CONCLUSION: On ferumoxtran-10-enhanced MR lymphangiography, contrast-enhanced images alone may suffice for lymph node characterization. However, a certain level of interpretation experience may be required before contrast-enhanced images can be used alone.

Adult↗
PubMed2006

Imaging-guided catheter drainage of abdominal collections with fistulous pancreaticobiliary communication.

OBJECTIVE: Our aim was to study the success of percutaneous imaging-guided catheter drainage of abdominal collections with documented fistulous pancreaticobiliary communication. MATERIALS AND METHODS: Fifty-seven patients (age range, 23-88 years) with abdominal collections who underwent imaging-guided catheter drainage were included in this retrospective study. These collections showed communication with either the pancreatic duct (n = 15) or the biliary duct (n = 42) on imaging. The imaging guidance included CT (n = 40), sonography (n = 17), and fluoroscopy (n = 4), either alone or in combination. The success of catheter drainage was described as resolution of the collection on follow-up imaging and clinical improvement. Other treatments directed toward management of leaks or collections were also recorded. RESULTS: The success rates of catheter drainage for abdominal collections with biliary and pancreatic ductal communication were 93% (39/42) and 67% (10/15), respectively. The difference was statistically significant (p = 0.01). The three complications seen in this study were pneumothorax in one patient, bowel perforation in one, and death in one. The drainage catheter was upsized in five patients and an additional catheter was needed in nine patients. CONCLUSION: Imaging-guided catheter drainage is a clinically useful option for drainage of abdominal collections that have pancreaticobiliary communications. The success rate is significantly better for collections with biliary communication than for those with pancreatic communication.

Adult↗
PubMed2006

Significance of incidental thyroid lesions detected on CT: correlation among CT, sonography, and pathology.

OBJECTIVE: The purpose of our study was to determine the prevalence of malignancy in incidental abnormalities of the thyroid gland detected on CT and to determine the relative accuracy of characterizing these abnormalities on CT as compared with sonography and pathology. MATERIALS AND METHODS: We searched our department's computerized clinical database for all thoracic and cervical CT scans in which a new abnormality was incidentally identified in the thyroid gland from 1998-2001. Two hundred thirty patients with abnormal findings in the gland on CT subsequently underwent thyroid sonography, and 118 of the 230 patients underwent a diagnostic biopsy or resection. CT and sonographic images were directly reviewed to identify imaging features of each thyroid abnormality, including the location, size, appearance, and presence or absence of calcifications. Associations were evaluated using Fisher's exact test of significance and the Student's t test. The overall rate of malignant and potentially malignant lesions among these incidental abnormalities of the thyroid gland was calculated. RESULTS: CT findings matched the sonographic characterization in 122 patients (53.0%), correctly identified the dominant nodule but missed multinodularity in 69 (30.0%) patients, and underestimated the number of nodules in 24 (10.4%) patients. CT overestimated the number of nodules in 5 (2.2%) patients and was false-positive for lesions in 10 patients (4.3%). Ninety-one patients with a single or dominant nodule on CT had pathologic correlation: 7 nodules were malignant, 17 showed malignant potential, and 67 were benign. Of 27 patients with multinodular or enlarged thyroid glands on CT and histopathologic correlation, 2 lesions were malignant and 25 benign. The presence of punctate calcifications on CT significantly correlated to the presence of microcalcifications on sonography (p < 0.02). Benign nodules were significantly smaller (mean, 2.16 +/- 1.01 cm; range, 0.6-4.5 cm) than malignant and potentially malignant nodules (mean, 2.79 +/- 0.99 cm; range, 0.7-4.6 cm) (p = 0.01). Patients 35 years or younger who had a thyroid lesion on CT were more likely to have malignancy (p < 0.01). Overall, among incidentally detected lesions of the thyroid gland, there was at least a 3.9% rate of malignancy (95% CI: 1.8-7.3%) and 7.4% rate of malignant potential (95% CI: 4.4-11.6%). CONCLUSION: There is at least an 11.3% prevalence of malignant or potentially malignant lesions among incidental thyroid abnormalities detected on CT. Patients 35 years or younger who have incidental abnormalities have a significantly greater rate of malignancy. No CT feature reliably distinguishes benign from malignant lesions in the thyroid gland. CT underestimates the number of nodules relative to sonography, which suggests that sonography is a useful adjunctive test after the incidental detection of a thyroid abnormality on CT.

Adult↗
PubMed2005

Distinguishing benign from malignant adrenal masses: multi-detector row CT protocol with 10-minute delay.

PURPOSE: To retrospectively evaluate the accuracy of precontrast attenuation, relative percentage washout (RPW), and absolute percentage washout (APW) in distinguishing benign from malignant adrenal masses at multi-detector row computed tomography (CT). MATERIALS AND METHODS: This HIPAA-compliant retrospective study had institutional review board approval; the need for informed consent was waived. One hundred twenty-two adrenal masses were evaluated in 99 patients (51 men, 48 women; age range, 37-86 years) who had undergone CT performed according to the study protocol and who either were given a pathologic diagnosis or underwent follow-up imaging. Unenhanced images were obtained before administration of 120 mL of an intravenous contrast agent with a 75-second scan delay. Delayed images were obtained after 10 minutes. RPW and APW were computed. Receiver operating characteristic (ROC) analysis was performed to compare mean attenuation and both RPW and APW. Analysis was first performed with the exclusion of pheochromocytomas, myelolipomas, and cysts. Precontrast attenuation criteria specific for benignity or malignancy were determined, and ROC analysis of results for the entire nonpheochromocytoma group was then performed. RESULTS: By using an RPW of 37.5% and excluding cysts and myelolipomas, all malignant lesions were detected with a sensitivity of 100% (17 of 17 lesions) and a specificity of 95% (90 of 95 lesions). Area under the binomial ROC curve (A(z)) values were 0.912, 0.985, and 0.892 for precontrast attenuation, RPW, and APW, respectively. Precontrast attenuation of less than 0 or more than 43 HU indicated benign and malignant entities, respectively. Incorporation of these criteria into the APW analysis yielded a sensitivity of 100% (17 of 17 lesions) and a specificity of 98% (93 of 95 lesions) for a threshold washout value of 52.0%. This attenuation-corrected APW generated the greatest A(z) value (ie, 0.988). Combining all the information available from the protocol yielded a sensitivity of 100% (17 of 17 lesions) and a specificity of 98% (98 of 100 lesions) for differentiating benign from malignant masses. CONCLUSION: Precontrast attenuation of less than 0 HU supercedes the washout profile in the evaluation of an individual adrenal mass. Noncalcified, nonhemorrhagic adrenal lesions with precontrast attenuation of more than 43 HU should be considered suspicious for malignancy.

Adrenal Gland Diseases↗
PubMed2005

Small incidental pulmonary nodules: how useful is short-term interval CT follow-up?

PURPOSE: To determine whether short-term (<6 month) follow-up imaging by thoracic CT is necessary to evaluate small (< or =4 mm) noncalcified nodules (NCN) in patients with no history of malignancy or acute lung disease. MATERIALS AND METHODS: We reviewed serial thoracic helical CT scans between 1999-2000 obtained for the evaluation or follow-up imaging of small NCNs. CT scans were performed at 5-mm collimation. Patients were excluded if they had a history of neoplasm, infection, pulmonary fibrosis, or immune deficiency; also excluded if nodule(s) > or =5 mm at intake, or no follow-up scan within 1 year. NCNs were evaluated for number, size, configuration, and change in size over time. Exact 95% Confidence Intervals were used to estimate chances of nodule growth in 3-, 6-, and 12- month intervals. RESULTS: A total of 1826 patients received a CT for NCNs. Four hundred fourteen patients met inclusion criteria (221 women, 193 men; mean age, 65.6 years). Eighty-five patients had a single NCN, 329 had multiple NCNs. One hundred seventy-three patients had additional > or =5 mm nodules. One hundred twenty-seven patients were lost to follow up within the 1-year period. Eight nodules cleared. None of the < or =4 mm NCNs grew on follow-up imaging within 12 months. Three patients developed lung cancer in other nodules > or =5 mm (5-10 mm). These nodules grew on follow up intervals of 3-13 months. One patient had a 19 mm benign hamartoma that grew in 9 months. The calculated chance that a NCN < or =4 mm will grow within 3, 6, and 12 months (95% CI) is < or =0.89%, 1.01%, and 1.28%, respectively. CONCLUSION: The chance of growth in < or =4 mm NCNs in a 3- to 6-month period in patients with no previous history of malignancy or immune disorder is small; therefore, short-term follow-up imaging (<12 month) for nodules < or =4 mm is not necessary.

Adult↗
PubMed2005

Assessing tumor perfusion and treatment response in rectal cancer with multisection CT: initial observations.

PURPOSE: To use first-pass perfusion computed tomography (CT) to prospectively investigate tumor vascularity in rectal cancer and to determine whether any of the perfusion parameters would predict tumor response to chemotherapy and radiation therapy. MATERIALS AND METHODS: The institutional review board approved this study, and informed prior consent was obtained from participants. Perfusion CT of rectal cancer was performed with four-section multi-detector row CT in 15 patients (13 men, two women; mean age, 62.1 years; age range, 46-84 years). Five patients with prostate cancer served as controls. All patients with rectal cancer underwent 6-8 weeks of chemotherapy and radiation therapy followed by surgery. In nine patients, perfusion CT was repeated after completion of chemotherapy and radiation therapy. Contrast medium-enhanced dynamic CT was performed with a static table position for 45 seconds, and the data were analyzed by using commercial software to calculate tissue blood flow (BF), blood volume, mean transit time (MTT), and vascular permeability-surface area product. Perfusion parameters of normal rectum and tumor were compared. Perfusion parameters before and after chemotherapy and radiation therapy were compared. A tumor was considered to have responded if its stage at pathologic analysis indicated regression compared with the preoperative stage. Baseline perfusion values were compared between responders and nonresponders. Statistical analysis was performed with the Student t test. RESULTS: Rectal cancer showed higher BF and shorter MTT compared with those of normal rectum (P < or =.05). After chemotherapy and radiation therapy, tumors showed significant reduction in BF and increase in MTT (P < or =.05). There was a significant difference in baseline BF and MTT values between responders and nonresponders (P < or =.05). Tumors in three patients with high initial BF and short MTT showed poor response. CONCLUSION: Perfusion CT of rectal cancer can enable assessment of tumor vascularity and perfusion changes that result from chemotherapy and radiation therapy. In this small patient sample, tumors with initial high BF and short MTT values tended to respond poorly to chemotherapy and radiation therapy.

Aged↗
PubMed2005

Polyp size at CT colonography after electronic subtraction cleansing in an anthropomorphic colon phantom.

PURPOSE: To evaluate the effect of various bowel contrast material concentrations and subtraction software on size measurements of well-defined polyp lesions in a colon phantom at CT colonography. MATERIALS AND METHODS: Repeated scanning and a precise reference standard required the use of a colon phantom in which 21 polyps were randomly distributed. Two readers who had each reviewed computed tomographic (CT) colonographic images from more than 100 cases evaluated polyp size on images obtained when the phantom was partially filled with varying concentrations of contrast material, scanned by using CT colonography, and subjected to electronic subtraction cleansing. The single largest dimension was recorded for each reader for a randomized series of polyps. These measurements were compared with a reference standard that was based on a combination of the manufacturer's polyp size specifications and the subsequent verification of these sizes by an independent consensus panel. Six weeks after initial observations, readers evaluated images of the phantom scanned without the presence of contrast material. Polyp size estimations for the two readers for each series were compared with the reference standard to obtain a mean absolute measurement error for each reader for each series. Data for each reader were compared by using a nonparametric Kruskal-Wallis analysis of variance test. A pair-wise comparison of the experimental and control series was then performed by using the Dunn post hoc test. RESULTS: Contrast material dilutions resulting in an average attenuation of less than 500 HU resulted in complete subtraction and the absence of streak artifacts. There was no statistically significant difference between the average measurement error for contrast attenuations between 300 and 500 HU when compared with that of control. Streak artifact was noticeable for the highest dilution (mean, 840 HU). No statistically significant differences were observed for series in which cleansing software was used in the absence of bowel contrast material. CONCLUSION: The combination of electronic cleansing and bowel contrast enhancement in the range of 300-500 HU results in no substantial change in readers' estimations of polyp size at CT colonography.

Analysis of Variance↗
PubMed2005

Fungus-infected fluid collections in thorax or abdomen: effectiveness of percutaneous catheter drainage.

PURPOSE: To retrospectively evaluate the effectiveness of percutaneous catheter drainage in the treatment of fungus-infected fluid collections in the thorax or abdomen and to identify any factor that may be predictive of a poor clinical outcome. MATERIALS AND METHODS: Approval for this study was obtained from the hospital ethics subcommittee on human studies. Because the study was retrospective, patient informed consent was not required. This study was compliant with the Health Insurance Portability and Accountability Act. Retrospective analysis was performed of cases of fungus-infected fluid collections in the thorax or abdomen treated by using percutaneous catheter drainage in 60 patients (36 male and 24 female patients; mean age, 57 years; range, 2 months to 91 years) during 5 years. The patient medical records were reviewed to identify recognized factors for predisposition to fungal infection. The details of percutaneous catheter drainage and microbiologic findings were recorded. The technical success (ability of catheters placed to drain collections treated) and the clinical success (ability of patients to recover fully without surgery) of percutaneous catheter drainage were determined. A multifactor logistic regression analysis was performed to identify any clinical or microbiologic factor predictive of a poor clinical outcome. RESULTS: Seventy-three fungus-infected fluid collections were drained in 60 patients. The collections originated from the pleura (n = 6), mediastinum (n = 2), liver (n = 3), pancreas (n = 5), obstructed biliary or urinary tract (n = 9), gallbladder (n = 1), and abdominopelvic area (n = 47). The technical success rate for catheter drainage was 79% (41 of 52 patients); the clinical success rate, 57% (34 of 60 patients). Twenty (33%) patients died from all causes during hospital admission. Multifactor logistic regression analysis was used to identify predictors of a poor clinical outcome; complexity of collection, history of malignancy, and admission to intensive care unit were significant (P < .03) and independent predictors. CONCLUSION: Despite a moderately high technical success rate with percutaneous catheter drainage of fungus-infected fluid collections, clinical success rate was much lower. Both imaging appearance (complexity of collection) and clinical factors (history of malignancy, admission to intensive care unit) influenced prognosis.

Abdomen↗
PubMed2005

Percutaneous cholecystostomy catheter removal and incidence of clinically significant bile leaks: a clinical approach to catheter management.

OBJECTIVE: We sought to determine the incidence of bile leaks upon removal of small-bore percutaneous cholecystostomy catheters and to evaluate clinical and imaging guidelines to ensure safe catheter removal. MATERIALS AND METHODS: A retrospective evaluation of all gallbladder drainages performed over a 5-year period revealed 163 patients (range, 7-98 years) who underwent percutaneous cholecystostomy catheter placement. Medical records and imaging studies were reviewed to assess the events at catheter removal (e.g., inadvertent removal, controlled removal with cholangiography without tract imaging, or controlled removal with cholangiography with tract imaging) and the incidence of major and minor bile leaks. RESULTS: The events at catheter removal were assessed in 66 patients. Group 1 was 45 patients whose catheters were removed after a minimum of approximately 3 weeks with a cholangiogram that established cystic and common duct patency and no imaging of the tract. Catheters were not removed until the patient recovered from acute illnesses that contributed to acalculous cholecystitis. Group 2 was 11 patients managed similarly to group 1 except that tract imaging was performed at catheter removal. Group 3 was 10 patients whose tubes came out inadvertently without cholangiogram or tract imaging. Two major (group 2 and group 3) and two minor (group 2) bile leaks occurred. No bile leaks occurred in group 1 (p = 0.006). CONCLUSION: Major bile leaks occurred in 3% of patients, and minor leaks occurred with equal frequency. Tract imaging may not be necessary in patients with small-bore gallbladder catheters who have recovered from critical illness, show patent cystic and common ducts, and have had catheters for 3-6 weeks.

Adolescent↗