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PubMed1980

HLA antigens, nasal polyps and asthma.

HLA typing has been performed on a selected series of 29 patients with nasal polyps, with or without asthma. Despite the small series there was a significant incease in the haplotype AI/B8 in patients with both nasal polyps and asthma. No association was found in those with polyps alone. However, those with both conditions, who were positive for AI/B8, had more severe polyp disease. Three out of 4 patients with nasal polyps, asthma and sensitivity to aspirin were positive for AI/B8. In patients with nasal polyps, tissue typing sensitivity to aspirin were positive for AI/B8. In patients with nasal polyps, tissue typing might be of use in predicting both those who are most at risk of developing asthma, and also those who are most likely to have severe polyp disease. The association of AI/B8 with severe polyp disease and asthma, may imply that abnormalities of immune response are likely to be associated with the pathogenesis of both conditions.

Adolescent↗
PubMed1987

Prostatic-type polyps of the lower urinary tract: three histogenetic types?

Seventeen prostatic-type polyps of the lower urinary tract are reported. All occurred in males, and the mean ages of the patients with ureteric orifice, bladder and urethral polyps were 20.5, 60.2 and 36.6 years, respectively. The commonest presentation for the bladder and ureteric orifice polyps was haematuria, whereas that for the urethral polyps was either dysuria or haematuria. The polyps consisted of acini and papillae lined by prostatic-type epithelium, as confirmed by immunostaining for prostatic-specific antigen. Most had interspersed islands or complete covering of transitional epithelium on the surface. We believe that the histogenesis of prostatic-type polyps may differ in the different sites. For the ureteric orifice polyp, the early age of presentation and the simple occurrence of prostatic acini beneath an intact urothelium suggest a developmental abnormality. For the bladder polyp, the late onset of disease and the commonly observed transition with cystitis cystica-glandularis suggest that it may be a metaplastic variant of cystitis cystica-glandularis. On the other hand, the urethral polyp probably represents a hyperplastic lesion, since the prostatic urethra is normally lined partly by prostatic-type epithelium.

Adolescent↗
PubMed1993

Diagnostic problems relating to uterine cervical polyps with malignancy.

In order to clarify the diagnostic problems relating to, and the proper treatment of, uterine cervical polyps, 951 polyps were analyzed clinicopathologically. All polyps were examined histopathologically and divided into 2 groups: benign polyps (Group-1), and polyps with neoplastic or malignant lesions (Group-2). Polyp size and cervical cytology are not always reliable for predicting the correct diagnosis of neoplastic or malignant lesions. Colposcopic diagnostic accuracy was 56.3%, but increased to 75.0% when combined with cytology. Neoplastic or malignant lesions were found at both the cervical polyp and the cervix in 21 out of 24 Group-2 patients (87.5%). These results suggest that in order not to miss rare neoplastic or malignant lesions in polyps and/or cervices, histopathological examinations of all polyps, aided by cervical cytology and colposcopic observation, are necessary.

Cell Transformation, Neoplastic↗
PubMed2001

Colonic chicken skin mucosa: association with juvenile polyps in children.

OBJECTIVES: Chicken skin mucosa is a newly described endoscopic finding associated with colonic neoplasms in adults. Chicken skin mucosa was sought in children with juvenile polyps to determine the prevalence, endoscopic features, and location. An alternative theory is proposed for the pathogenic mechanism of this finding. METHODS: Children having colonoscopy and polypectomy were prospectively evaluated for the presence of chicken skin mucosa. The location of the polyps was determined at colonoscopy; the size of removed polyps was measured during processing of samples in pathology. Biopsies from colonic chicken skin mucosa were stained with hematoxylin and eosin and mucicarmine. RESULTS: Over a 1-yr period, 27 juvenile polyps were removed from 15 children at colonoscopy. Eleven of 15 children (73%) were found to have polyps with chicken skin mucosa; overall, 43% of the polyps had associated chicken skin mucosa. Chicken skin mucosa-positive polyps were larger than chicken skin mucosa-negative polyps and were only found in the rectosigmoid colon. Lipid-laden macrophages were found in all samples of chicken skin mucosa tested. CONCLUSIONS: Chicken skin mucosa is a common finding in children with juvenile polyps. It probably is the result of local mucosal trauma, rather than a preneoplastic lesion.

Adolescent↗
PubMed2001

Serum and colon mucosa micronutrient antioxidants: differences between adenomatous polyp patients and controls.

OBJECTIVES: Micronutrient antioxidants, by virtue of their free radical scavenging properties, are potential chemopreventive agents against colon cancer. Yet, little is known about the actual concentration of these antioxidants in colonic mucosa. It is also not known whether a relationship exists between serum and mucosal tissue antioxidant levels. Previous studies evaluating the occurrence of polyps after supplementation with vitamin E and beta-carotene have yielded mixed results. The aim of this study was to determine the concentrations of seven micronutrient antioxidants (alpha- and gamma-tocopherol, lutein, beta-cryptoxanthin, lycopene, and alpha- and beta-carotene) in colonic mucosa and to determine whether serum levels of each antioxidant could predict levels of that antioxidant in the right and left colon of patients with normal mucosa or in those with adenomatous polyps. METHODS: Mucosal tissue concentrations and serum levels of antioxidants were determined in 10 patients with adenomatous polyps and 15 control subjects (GI patients with normal colonic mucosa). Mucosal tissue samples were obtained from both the right and left colon in all patients. RESULTS: Patients with polyps similar serum antioxidant status similar to that of control. However, polyp patients had significantly lower concentrations of all seven antioxidants in both the right (p < 0.0070) and left colon (p < 0.0026) than did controls. Finally, serum antioxidant levels predict right and left colon antioxidant levels in controls but not in patients with polyps. CONCLUSIONS: Patients with adenomatous polyps have low levels of micronutrient antioxidants in their colon mucosa. Because the serum levels of these antioxidants were similar in controls and polyp patients, our findings suggest an increased level of free radical activity in patients with polyps compared to normal subjects.

Adenomatous Polyps↗
PubMed2004

Registration of central paths and colonic polyps between supine and prone scans in computed tomography colonography: pilot study.

Computed tomography colonography (CTC) is a minimally invasive method that allows the evaluation of the colon wall from CT sections of the abdomen/pelvis. The primary goal of CTC is to detect colonic polyps, precursors to colorectal cancer. Because imperfect cleansing and distension can cause portions of the colon wall to be collapsed, covered with water, and/or covered with retained stool, patients are scanned in both prone and supine positions. We believe that both reading efficiency and computer aided detection (CAD) of CTC images can be improved by accurate registration of data from the supine and prone positions. We developed a two-stage approach that first registers the colonic central paths using a heuristic and automated algorithm and then matches polyps or polyp candidates (CAD hits) by a statistical approach. We evaluated the registration algorithm on 24 patient cases. After path registration, the mean misalignment distance between prone and supine identical anatomic landmarks was reduced from 47.08 to 12.66 mm, a 73% improvement. The polyp registration algorithm was specifically evaluated using eight patient cases for which radiologists identified polyps separately for both supine and prone data sets, and then manually registered corresponding pairs. The algorithm correctly matched 78% of these pairs without user input. The algorithm was also applied to the 30 highest-scoring CAD hits in the prone and supine scans and showed a success rate of 50% in automatically registering corresponding polyp pairs. Finally, we computed the average number of CAD hits that need to be manually compared in order to find the correct matches among the top 30 CAD hits. With polyp registration, the average number of comparisons was 1.78 per polyp, as opposed to 4.28 comparisons without polyp registration.

Algorithms↗
PubMed2004

Colorectal polyps and cancers in asymptomatic average-risk patients: evaluation with CT colonography.

PURPOSE: To compare thin-section multi-detector row computed tomographic (CT) colonography with conventional colonoscopy in the evaluation of colorectal polyps and cancer in asymptomatic average-risk patients. MATERIALS AND METHODS: Sixty-eight asymptomatic men (age > 50 years) scheduled to undergo screening colonoscopy were enrolled in this study. CT colonography was followed by conventional colonoscopy, performed on the same day. Supine and prone CT colonography were performed after colonic insufflation with room air. A gastroenterologist measured all polyps, which were categorized as 1-5, 6-9, or over 10 mm. Biopsy and histologic evaluation were performed of all polyps. CT colonography and colonoscopy results were compared for location, size, and morphology of detected lesions. Point estimates and 95% CIs were provided for specificity and sensitivity of CT by using results at conventional colonoscopy as the reference standard. RESULTS: At colonoscopy, 98 polyps were identified in 39 patients; 21 (21.4%) of 98 were detected at CT colonography. Sensitivity was 11.5% (nine of 78) for polyps 1-5 mm, 52.9% (nine of 17) for polyps 6-9 mm, and 100% (three of three) for polyps over 10 mm. Results at colonoscopy were normal in 29 (42.6%) of 68 patients; at CT colonography, results were correctly identified as normal in 26 of these 29 patients. In one of these patients, a lesion larger than 10 mm was detected at CT colonography. The per-patient specificity of CT was 89.7% (26 of 29; 95% CI: 72.7%, 97.8%). The mean time for CT image interpretation was 9 minutes. CONCLUSION: In patients at average risk for colorectal cancer, CT colonography is a sensitive and specific screening test for detecting polyps 10 mm or larger; the sensitivity for detecting smaller polyps is decreased. Examination findings can be interpreted in a clinically feasible amount of time.

Animals↗
PubMed2005

Linear polyp measurement at CT colonography: in vitro and in vivo comparison of two-dimensional and three-dimensional displays.

PURPOSE: To compare the accuracy of polyp measurement at computed tomographic (CT) colonography by using two-dimensional (2D) multiplanar reformation (MPR) and three-dimensional (3D) endoluminal displays obtained both in a colon phantom and at clinical examinations. MATERIALS AND METHODS: This HIPAA-compliant study had institutional review board approval, and all patients provided signed informed consent, both of which allowed for additional retrospective evaluation. Two-dimensional and 3D CT colonography displays were generated from data obtained in an in vitro colon phantom that contained 10 6-13-mm synthetic polyps and from data obtained at in vivo clinical CT colonography examinations performed in 10 patients (five men, five women; mean age, 56.3 years) with proved polyps (size range, 7-25 mm). The reference standard for in vivo polyp size was optical colonoscopic measurement with a calibrated linear probe. Polyps were measured at CT colonography with 2D MPR and 3D endoluminal displays and electronic calipers by four radiologists who were unaware of the reference size measurements. The largest of the three 2D MPR measurements was considered the "optimized" 2D projection. Statistical analysis was performed with Wilcoxon signed rank, repeated-measures analysis of variance, and paired t testing. RESULTS: For the phantom, the mean errors (differences between actual polyp size and that measured at CT colonography) for 2D transverse, 2D coronal, and 3D endoluminal displays were 1.6 mm +/- 0.8 (standard deviation), 1.4 mm +/- 0.7, and 0.8 mm +/- 0.5, respectively. For in vivo polyp measurements, the mean errors for 2D transverse, 2D coronal, 2D sagittal, and 3D displays were 4.4 mm +/- 3.5, 3.8 mm +/- 3.3, 4.6 mm +/- 3.0, and 1.9 mm +/- 1.6, respectively. The 2D measurements underestimated actual polyp sizes in all cases. The differences in mean errors between 2D MPR and 3D endoluminal measurements were significant (P < .05). When the optimized 2D view was considered for in vivo measurement, the mean error decreased to 3.0 mm +/- 2.6 (P = .2). CONCLUSION: Linear polyp measurement on 3D endoluminal views was significantly more accurate than measurement on 2D transverse, coronal, or sagittal views, both in vitro and in vivo, for the CT colonography system evaluated. Use of the optimized 2D view substantially reduced 2D measurement error and may be valuable when used in conjunction with 3D measurement.

Analysis of Variance↗
PubMed2006

Detection of colorectal polyps: comparison of multi-detector row CT and MR colonography in a colon phantom.

PURPOSE: To compare multi-detector row (four- and 16-section) computed tomography (CT), including a low-dose protocol, with high-field-strength (1.5- and 3.0-T) magnetic resonance (MR) imaging for reader detection of colorectal polyps in a colon phantom. MATERIALS AND METHODS: A colon phantom with simulated haustral folds and 10 polyps of varying size (2.0-8.0 mm) was imaged at four- and 16-section CT (section thicknesses of 1.25 and 0.75 mm, reconstruction increments of 0.8 and 0.7 mm, and 100 and 10 mAs, respectively, and 120 kV for both) and at 1.5- and 3.0-T MR imaging (three-dimensional gradient-recalled echo sequence, section thickness of 1.4 mm). Three-dimensional endoluminal images were assessed by 10 reviewers for each modality regarding polyp detection. Comparisons of sensitivities were performed by using logistic regression. RESULTS: Overall, polyps were detected with a sensitivity of 87% (95% confidence interval [CI]: 80%, 94%) at four-section CT, 92% (95% CI: 87%, 97%) at 16-section CT, 56% (95% CI: 46%, 66%) at 1.5-T MR imaging, and 55% (95% CI: 45%, 65%) at 3.0-T MR imaging. The detection of polyps at least 4 mm in diameter was not influenced by the modality or radiation dose (sensitivity of 100%). CT performed in low-dose mode depicted all polyps with a diameter of at least 3 mm. Polyps smaller than 3 mm in diameter were detected with a sensitivity of 7.5% (1.5-T MR imaging), 22.5% (3.0-T MR imaging), and 20% (low-dose CT); detection rates were significantly greater (P < .001) with normal-dose CT (four section, 67.5%; 16 section, 82.5%). Increased spatial resolution (with CT) and higher field strength (with MR imaging) had no significant effect on polyp detection. CONCLUSION: With both multi-detector row CT and MR imaging, readers detected polyps above the clinically relevant threshold diameter of 6 mm, with similar sensitivities.

Colonic Polyps↗
PubMed2006

CT colonography with computer-aided polyp detection: volume and attenuation thresholds to reduce false-positive findings owing to the ileocecal valve.

PURPOSE: To retrospectively identify volume and average attenuation thresholds for differentiating between ileocecal valve (ICV) and polyp at computed tomographic (CT) colonography with computer-aided detection (CAD). MATERIALS AND METHODS: Informed consent (with consent for future retrospective research) and institutional review board (IRB) approval were obtained for the original prospective study. This retrospective study had IRB approval, as well, and was HIPAA-compliant. A total of 496 patients were selected from a larger screening population. CT colonographic images from 394 patients (227 men, 167 women; mean age, 58.0 years; range, 40-79 years) were used as a training set, and images from 102 patients (76 men, 26 women; mean age, 59.8 years; range, 46-79 years) were used as a test set. A series of 2742 volume and attenuation thresholds, for which segmented findings both larger in volume and lower in average attenuation were labeled as ICVs and remaining findings were labeled polyps, were applied to the training set to determine settings with 100% sensitivity for polyp detection and the highest specificity for ICV detection. The optimal settings were then applied to the test set. Significance was assessed with the Fisher exact test, and 95% confidence intervals (CIs) were computed for sensitivity and specificity. RESULTS: A total of 386 ICVs and 67 adenomatous polyps from the training set and 102 ICVs and 138 adenomatous polyps from the test set could be segmented with a three-dimensional segmentation algorithm. When supine and prone images were counted individually, 746 nonunique ICVs from the training set and 191 from the test set were segmentable. In the training set, a volume of 600 mm(3) and an attenuation of 36 HU provided 100% sensitivity (67 polyps; 95% CI: 93%, 100%) and the optimal 83% specificity (618 of 746 ICVs; 95% CI: 80%, 85%). When applied to the test set, this combination provided 97% sensitivity (134 of 138 polyps; 95% CI: 92%, 99%) and 84% specificity (160 of 191 ICVs; 95% CI: 78%, 89%). Differences in sensitivity and specificity in the detection of polyps between the sets were not significant. CONCLUSION: Volume and average CT attenuation thresholds can help differentiate most ICVs from true polyps.

Adult↗
PubMed2006

CT colonography: automated measurement of colonic polyps compared with manual techniques--human in vitro study.

PURPOSE: To prospectively investigate the relative accuracy and reproducibility of manual and automated computer software measurements by using polyps of known size in a human colectomy specimen. MATERIALS AND METHODS: Institutional review board approval was obtained for the study; written consent for use of the surgical specimen was obtained. A colectomy specimen containing 27 polyps from a 16-year-old male patient with familial adenomatous polyposis was insufflated, submerged in a container with solution, and scanned at four-section multi-detector row computed tomography (CT). A histopathologist measured the maximum dimension of all polyps in the opened specimen. Digital photographs and line drawings were produced to aid CT-histologic measurement correlation. A novice (radiographic technician) and an experienced (radiologist) observer independently estimated polyp diameter with three methods: manual two-dimensional (2D) and manual three-dimensional (3D) measurement with software calipers and automated measurement with software (automatic). Data were analyzed with paired t tests and Bland-Altman limits of agreement. RESULTS: Seven polyps (<or=6-mm diameter) could not be extracted by using the software; 20 polyps (5-15-mm diameter) remained for analysis. Automated measurement was not significantly different from histologic size for the experienced reader (mean difference, 0.63 mm; P=.06) or novice reader (mean difference, 0.58 mm; P=.12). With manual 2D measurement and manual 3D measurement, the experienced reader (1.21-mm mean difference, P<.001, and 0.68-mm mean difference, P=.03, respectively) and novice reader (1.54-mm mean difference, P<.001, and 0.84-mm mean difference, P=.002, respectively) significantly underestimated polyp size. Interobserver agreement was good and similar for all three methods (95% limits of agreement span, approximately 2.5 mm). Intraobserver agreement was related to reader experience, with differences of up to 2.5 mm within expected limits of agreement. CONCLUSION: For polyps smaller than 1 cm, measurement differences of up to 2.5 mm are within the expected limits of inter- and intraobserver agreement for all measurement techniques. Automated and manual 3D polyp measurements are more accurate than manual 2D measurements.

Adolescent↗
PubMed2005

Tissue-specific immunoglobulin E in human nasal polyps.

Allergy is generally believed to be an underlying cause of nasal polyps. The objective of this study was to define allergic nasal polyps. We investigated specific immunoglobulin E (sIgE) in polyp tissue. Thirty pieces of polyp tissue were taken from patients with positive allergic symptoms, and 30 from patients without allergic symptoms. Nasal polyp tissue homogenate and serum from these patients were prepared for detecting sIgE by a CAP method. For patients with allergic symptoms and/or positive serum CAP test results, the rates of positive tissue CAP tests were low: 36.7% and 35.7%, respectively. However, nearly all of the tissue CAP-positive subjects had allergic symptoms and positive serum CAP tests. We conclude that the local tissue sIgE profile reflects more specifically the allergic status of patients with nasal polyps than does the systemic serum test or the presentation of allergic symptoms. Thus, polyp tissue CAP tests might be performed in patients with positive allergic symptoms and positive serum CAP tests to define an allergy-induced polyp precisely. Then, specific antiallergic treatment could be administered to prevent polyp recurrence.

Adult↗
PubMed1987

Prostaglandins, leukotrienes, and other arachidonic acid metabolites in nasal polyps and nasal mucosa.

Prostaglandins (PGs) and leukotrienes (LTs) are known to play an important role in allergic inflammatory reactions. The triad of aspirin sensitivity, nasal polyposis, and asthma led us to suspect that PGs, LTs and other arachidonic acid metabolites may be involved in the pathogenesis of nasal polyps. The purpose of this study was to determine arachidonic acid metabolites and to measure concentrations of PGs and LTs in nasal polyps and nasal mucosa. Samples of nasal polyps and nasal mucosa were obtained at the time of polypectomies and nasal procedures. Metabolites of arachidonic acid in tissue were determined by incubation of tissue-homogenates with 14C-arachidonic acid and analyses with thin-layer chromatography and high performance liquid chromatography (HPLC). Levels of PGE2, 6-keto-PGF1 alpha, thromboxane (Tx)B2, 15-hydroxyeicosatetraenoic acid (HETE), LTC4, LTB4 were measured by radioimmunoassay. The predominant arachidonic acid metabolite in both nasal polyps and mucosa with 15-HETE. The HPLC analysis showed that the predominant metabolite in nasal polyp was 15-HETE, especially in polyps from aspirin sensitive patients. Levels of 15-HETE and PGE2 were higher in polyps from patients with a history of allergy than from nonallergic patients. Levels of LTC4 and LTB4 in nasal polyps were determined. The findings of this study will help to explain biochemical basis of the pathogenesis of aspirin-sensitive nasal polyps and to develop better medical treatment for them.

6-Ketoprostaglandin F1 alpha↗
PubMed1993

An analysis-by-synthesis approach to the estimation of vocal cord polyp features.

This paper deals with a new noninvasive method of estimating vocal cord polyp features through hoarse-voice analysis. A noteworthy feature of this method is that it enables us not only to discriminate hoarse voices caused by pathological vocal cords with a single golf-ball-like polyp from normal voices, but also to estimate polyp features such as the mass and dimension of polyp through the use of a novel model of pathological vocal cords which has been devised to simulate the subtle movement of the vocal cords. A synthetic hoarse voice produced with a hoarse-voice synthesizer is compared with a natural hoarse voice caused by the vocal cord polyp in terms of a distance measure and the polyp features are estimated by minimizing the distance measure. Some estimates of polyp dimension that have been obtained by applying this procedure to hoarse voices are found to compare favorably with actual polyp dimensions, demonstrating that the procedure is effective for estimating the features of golf-ball-like vocal cord polyps.

Acoustics↗
PubMed2001

The effect of electrothermal cautery-assisted resection of diminutive colonic polyps on histopathologic diagnosis.

We examined diminutive colonic polyps to identify relationships between thermal electrocoagulation or resection trauma cytologic artifacts, type of thermal electrocoagulation, polyp size, and the interobserver variation among 3 pathologists. The 3 pathologists independently evaluated 119 colonic polyps 5 mm or less in maximum dimension for diagnosis and degree of thermal electrocoagulation or resection trauma cytologic artifacts. The maximum dimension of the polyps and type of thermal electrocoagulation were recorded. The average percentage of polyps in which a definitive diagnosis could not be made because of cytologic artifacts was 16.5% (range, 11.8%-19.3%). Decreasing polyp size was associated linearly with the inability to make a definitive diagnosis owing to cytologic artifacts. Polyps smaller than 2 mm significantly more often could not be definitively diagnosed by at least 1 pathologist owing to cytologic artifacts, including some polyps that were excised without thermal electrocautery. Interobserver variation increased with decreasing polyp dimension. Two millimeters seems to represent a cut point, below which the likelihood that a definitive diagnosis can be made can be increased if thermal electrocoagulation is used. This small size seems to make them especially susceptible to cytologically injurious forces.

Adenoma↗
PubMed2003

Hyperplastic-like colon polyps that preceded microsatellite-unstable adenocarcinomas.

We compared hyperplastic-like polyps that preceded microsatellite-unstable adenocarcinomas to incidental hyperplastic polyps to identify distinguishing morphologic criteria. The study group included 106 hyperplastic-like, nonadenomatous, serrated polyps, most from the ascending colon in 91 patients; the control group included 106 rectosigmoid hyperplastic polyps from 106 patients in whom adenocarcinoma did not develop. Study group polyps had an expanded crypt proliferative zone, a serrated architectural outline that became apparent in the basilar crypt regions, basilar crypt dilation, inverted crypts, and a predominance of dysmaturational crypts (crypts with minimal cell maturation). In contrast, control group polyps had a proliferative zone confined to the basal crypt region, serrated architecture that became apparent in the superficial crypt region, rare to no basilar crypt dilation, and rare or no dysmaturational crypts. Hyperplastic-like polyps that preceded microsatellite-unstable adenocarcinomas had a distinctive constellation of morphologic features related to altered and decreased cell function and control that resulted in dysmaturational crypts. Dysmaturation constitutes a range of morphologic alterations, some of which overlap with incidental-type innocuous hyperplastic polyps. The morphologic features described herein provide initial guidelines to identify this potentially important subset of premalignant serrated-like polyps.

Adenocarcinoma↗
PubMed2006

Polyp volume versus linear size measurements at CT colonography: implications for noninvasive surveillance of unresected colorectal lesions.

OBJECTIVE: Proposed surveillance of unresected medium-sized (6.0-9.9 mm) polyps will require reliable detection of small incremental changes. The purpose of this study was to assess the reproducibility of linear versus volume measurements of polyp size at CT colonography (CTC) and to correlate results with a hemispheric model. MATERIALS AND METHODS: The study group consisted of 30 polyps on supine and prone CTC data sets. Measurements were performed separately by two experienced radiologists using the same CTC system (Vitrea 2), resulting in 120 linear and volume measurements. Linear size was defined as the longest dimension among the 2D multiplanar reconstruction views. Semiautomated volume determination required manual tracing of polyp boundaries on 2D multiplanar reconstruction views. The relative error between reviewers 1 and 2 was defined as 100 x (/D1 - D2/)/D(ave) for linear size (D) and as 100 x (/V1 - V2)/V(ave) for volume (V), where ave is average. RESULTS: The mean relative error for linear size and volume measurement was 10.4% +/- 10.7% and 16.9% +/- 13.2%, respectively. Median linear size and volume of polyps were 9.4 mm and 270 mm3, respectively. CTC-derived volumes for medium-sized polyps closely approximated hemispheric volume (V = (pi/12) x D(b), where b =3.13, r2 = 0.90). Small incremental changes in hemispheric size result in a 3:1 relative change in volume versus diameter, such that a 1-mm diameter change in a medium-sized hemispheric polyp results in a relative change in linear size and volume ranging from approximately 11-18% and 31-53%, respectively. CONCLUSION: Because changes in polyp volume are amplified compared with linear dimension, volume measurement rather than diameter measurement will better allow detection of small incremental changes in polyp size using CTC.

Colonic Polyps↗
PubMed2007

Combined CT colonography and 18F-FDG PET of colon polyps: potential technique for selective detection of cancer and precancerous lesions.

OBJECTIVE: The purpose of this study was to determine the feasibility of imaging the colon with fused CT colonography (CTC) and 18F-FDG PET and to correlate the findings with the histologic features of polyps. SUBJECTS AND METHODS: Eighteen patients with suspected colorectal polyps enrolled in this prospective study. Before colonoscopy, 17 of the patients underwent a combination of FDG PET and CTC. CTC consisted of 4-MDCT merged with PET. PET of the abdomen and pelvis was performed after each CTC scan. One radiologist and one nuclear medicine physician in consensus analyzed PET and CTC fusion data. PET standard uptake value was correlated with the findings at histologic examination of polyps. Patient feasibility was defined as the ability to tolerate prolonged scanning with good colonic distention. Technical feasibility was determined by how closely anatomically matched polyps overlapped on fusion images. RESULTS: Seventeen of 18 patients tolerated scanning. Eighty-five percent of colon segments were optimally distended. Twenty-three of 27 FDG-avid polyps measuring 10 mm or more had excellent overlap at fusion imaging. PET depicted 23 of 39 premalignant polyps and even showed increased tracer activity associated with four small tubular adenomas (4-6 mm). Sixteen benign polyps (10-25 mm) were not depicted on PET. All nine cases of cancer (tumors measuring 11-60 mm) were detected with both PET and CTC. The standard uptake value of malignant tumors ranged from 4 to 20 (mean, 9). However, six benign flat polyps did not exhibit FDG avidity. CONCLUSION: The novel combination of CTC and PET was feasible in 17 of 18 patients and allowed excellent image correlation in 23 of 27 proven polyps measuring 10 mm or more on PET-CTC fusion. This technique shows promise in accurate anatomic correlation of both malignant and premalignant lesions evaluated with FDG PET.

Adolescent↗