Diagnostic Performance of CT Colonography for the Detection of Colorectal Polyps

OBJECTIVE: To investigate the diagnostic value of CT colonography for the detection of colorectal polyps. MATERIALS AND METHODS: From December 2004 to December 2005, 399 patients underwent CT colonography and follow-up conventional colonoscopy. We excluded cases of advanced colorectal cancer. We retrospectively analyzed the CT colonography findings and follow-up conventional colonoscopy findings of 113 patients who had polyps more than 6 mm in diameter. Radiologists using 3D and 2D computer generated displays interpreted the CT colonography images. The colonoscopists were aware of the CT colonography findings before the procedure. RESULTS: CT colonography detected 132 polyps in 107 of the 113 patients and conventional colonoscopy detected 114 colorectal polyps more than 6 mm in diameter in 87 of the 113 patients. The sensitivity of CT colonography analyzed per polyp was 91% (41/45) for polyps more than 10 mm in diameter and 89% (101/114) for polyps more than 6 mm in diameter. Thirteen polyps were missed by CT colonography and were detected on follow-up conventional colonoscopy. CONCLUSION: CT colonography is a sensitive diagnostic tool for the detection of colorectal polyps and adequate bowel preparation, optimal bowel distention and clinical experience are needed to reduce the rate of missing appropriate lesions.

What is the Best MR Sequence to Evaluate

PURPOSE: To determine the best MR sequence for evaluation of the anatomical structures of normal kidney. MATERIALS AND METHODS: Twenty normal volunteers (M:F=15:5) took part in this study, and for each, seven sequences were performed. The T1 weighted sequences were conventional spin echo T1 (Conv-SET1), turbo spin echo T1 (TSET1), and fast low angle shot (FLASH), while the T2 weighted sequences were turbo spin echo T2 (TSET2), half-Fourier acquisition single-shot turbo spin echo (HASTE), true-fast imaging with steady-state precession (True-FISP), and echoplanar imaging (EPI). The study involved quantitative and qualitative analysis. In quantitative analysis, CNRs between cortex and adjacent fat tissue, and between cortex and medulla were calculated from SNR (signal to noise ratio), and the CNRs of sequences were statistically compared. In quantative analysis, three radiologists collectively evaluated kidney outline, corticomedullary division, the renal vessels, the pelvis/ureter, and artifacts. For each sequence a grade was assigned, and for each parameter the grades were compared. RESULTS: Between cortex and adjacent fat, the highest CNR was shown by TSET1, followed by Conv-SET1,while among T2 sequences, the CNR shown by TSET2 was highest. Between cortex and medulla, the CNR demonstrated by the three T1 sequences showed no statistically significant difference. Among T2 sequences, however, HASTE showed the highest CNR, followed by EPI, and statistically, the findings for these two were significantly different from those of other T2 sequences. Among T1 sequences, FLASH provided the best kidney outline, though among T2-sequences there was no statistically significant difference. FLASH was also the best for cortico-medullary distinction, while for this purpose the best T2 sequence was HASTE. True-FISP was best for the evaluation of renal vessels, and HASTE for evaluating the pelvis and ureter. Artifacts were most prominent on Conv SET1. CONCLUSION: For evaluating the shape of the kidney, the best T2 sequence was TSET2, but the best T1 sequence could not be determined. For cortico-medullary differentiation, the best T1 sequence was FLASH and the best T2 sequence was HASTE. For the evaluation of renal vessels, True-FISP was best, and for the pelvis and ureter, HASTE. Artifacts were most prominent on Conv-SET1.

Hepatocellular Carcinoma: Comparison Study on Detecting Tumor Vascularity among Various Imaging Techniques

PURPOSE: To compare the detectability of tumor vascularity using triphasic spiral CT, angiography, CT during hepatic arteriography(CTHA) and single-level dynamic CTHA(SLD-CTHA). MATERIALS AND METHODS: Seventy-nine pathologically confirmed nodular hepatocellular carcinomas(HCCs) in 77 patients were included in this study. Sixty patients were male and 17 were female, and their ages ranged from 31 to 77 (average, 57.4) years. HCCs were classified into three groups according to the size: less than 2 cm (n=20), 2 -4 cm (n=32), and more than 4 cm (n=27) in diameter. If a portion of tumor demonstrated greater enhancement than surrounding liver parenchyma, vascularity was deemed to be present. Detectability by each imaging technique was compared according to size and overall. RESULTS: Hypervascularity was frequently detected by SLD-CTHA [90.9%(40/44)], followed by CTHA[88.0%(66/75)], angiography [80.3%(61/76)], triphasic spiral CT [72.4%(42/58)]. In the less than 2 cm group, detectability rates for triphasic spiral CT, angiography, CTHA and SLD-CTHA were 53.3%(8/15), 55.6%(10/18), 76.5%(13/17) and 87.5%(6/7), respectively. while the 2 -4 cm group demonstrated corresponding figures of 71.4%(15/21), 78.1%(25/32), 84.4%(27/32) and 86.4%(19/22). In the more than 4 cm group, the rate for triphasic spiral CT was 86.4%(19/22), while for angiography, CTHA and dynamic CTHA, it was 100%. CONCLUSION: In the detection of hypervascularity of HCC, SLD-CTHA showed the highest rate, followed by CTHA, angiography, and triphasic spiral CT. In HCCs less than 4 cm in diameter, the corresponding ordering was SLD-CTHA, CTHA, angiography and triphasic spiral CT, but in HCCs of more than 4 cm, angiography, CTHA and SLD-CTHA detected hypervascularity equally well. Lesion size most affected the findings of angiography.

CT Staging of Renal Cell Carcinoma Using the Revised 1997 TNM Staging Criteria: In Comparison with the Previous One

PURPOSE: To assess the accuracy of preoperative CT staging of RCC and to compare the relationship between T stage and the incidence of metastasis on the basis of the old (1992) and the new (1997) UICC & AJCC tumor classification system. MATERIALS AND METHODS: In 112 cases of surgically resected RCC, the stagings of preoperative CT scans were de-termined retrospectively by two radiologists and were compared with the results of pathologic examinations. In 70 cases which had been followed up over three years after surgery, the incidence of metastasis at initial diagnosis and during the follow-up period was assessed. All cases were reconsidered, and using the old and the new TNM classification, the incidence of metastasis was compared. RESULTS: According to the old TNM classification, 5 cases (4%) were staged at T1, 73(65%) at T2, 21(19%) at T3a, 9(8%) at T3b, 0 at T3c, and 4(4%) at T4. Using the new TNM classification, we also staged 54 cases (48%) at T1 and 24(21%) at T2. Overall, using this new classification, CT correctly staged 79% of patients (88/112) overstaged 15%(17/112) and understaged 6%(7/112) . CT had a sensitivity of 84% and specificity of 91% in new T1 tumors, 71% and 95%, respectively, in new T2 tumors, 69% and 88% in T3a tumors, 78% and 98% in T3b tumors, and 75% and 99% in T4 tumors. CT had a sensitivity of 44% and a specificity of 99% in old T1 tumors, and 82% and 71%, respectively, in old T2 tumors. The incidence of metastasis in CT-staged (cT) tumors was 0% (0/4) in old cT1, 8% (3/39) in new cT1, 29% (4/14) in new cT2, 67% (6/9) in cT3a, and 75% (6/8) in cT3b. CONCLUSION: In the staging of T1 tumors, CT is more sensitive when the new TNM classification is used. Even though the cut off point between T1 and T2 tumors had been in creased from 2.5 to 7.0 cm, T1 tumors staged according to the new system did not show a significantly higher incidence of metastasis than those staged according to the old.

High-Resolution CT in Patients with Chronic Airflow Obstruction: Correlation with Clinical Diagnosis and Pulmonary Function Test

PURPOSE: To determine the utility of HRCT in the diagnosis of chronic airflow obstruction and to correlate the morphologic abnormalities revealed by this modality with functional impairment in patients with chronic air-flow obstruction. MATERIALS AND METHODS:This study involved 80 patients with chronic airflow obstruction who underwent HRCT and a pulmonary function test. Final clinical diagnosis in these patients was determined by a chest physician on the basis of clinical features, bronchoscopy, pulmonary function test, and HRCT. In order to diagnose and determine the extent of areas of decreased attenuation revealed by HRCT (the CT score), the find-ings of HRCT were retrospectively reviewed by two radiologists, who reached a consensus. Clinical and HRCT diagnoses were then compared, and the rate of agreement between them was calculated. The relation-ship between the extent of areas of decreased attenuation revealed by HRCT and by FEV1/FVC was evaluated using Correl 's account and Student 's unpaired t-test. RESULTS: The agreement rate between clinical and HRCT diagnoses was 77.5% (62/80). The rates for bronchiec-tasis (88.9%, 24/27), emphysema (93.9%, 31/33), and bronchiolitis obliterans (100%, 6/6) were considerably higher than those for chronic bronchitis and bronchial asthma. The correlation rate between CT score and FEV1/FVC was significant in bronchiectasis (p0.05). CONCLUSION: HRCT is valuable in the diagnosis and prediction of physiologic impairment in patients with bronchiectasis and bronchiolitis obliterans, but has limited value in those with emphysema, chronic bronchitis or asthma.

Pseudolesions around the Gallbladder Fossa: Comparison of Frequency and Radiological Characteristics in Multiphasic CT, CTAP, and CTHA

PURPOSE: The purpose of this study is to compare the frequency with which pseudole-sions around the gallbladder (GB) fossa are revealed by multiphasic CT, by CT during arterial portography (CTAP), and by CT during hepatic arteriography (CTHA) and to determine their radiological characteristics. MATERIALS AND METHODS:Multiphasic CT, CTAP, and CTHA examinations of 81 patients without pathology of the GB and around the GB fossa were evaluated for pseudolesion around the GB fossa. The definition of pseudolesion was as follows: 1) hyperattenuation during the arterial phase and isoattenuation during the delayed phase of multipha-sic CT, or perfusion defect on CTAP and hyperattenuation on CTHA; 2) no Lipiodol tagging on Lipiodol CT; 3) all findings observed adjacent to the gallbladder fossa; and 4) no interval change on follow-up CTAP and CTHA. We compared the frequency of pseudolesions around the GB fossa, as seen on multiphasic CT, CTAP, and CTHA, and determined their size, location, and shape, as revealed by CTHA. RESULTS: The frequency of pseudolesion was 2.5% (2/81) on multiphasic CT, while on CTAP or CTHA, the frequency was 53.1% (43/81), and 58 pseudolesions were identi-fied. Of 58 pseudolesions, 56 were revealed by CTAP and 57 by CTHA. Forty-nine of 58 pseudolesions were larger and all pseudolesions showed more contrast to parenchyma on CTHA than on CTAP. The location of pseudolesions was segment V(32 of 58), IV (25 of 58), and VI (1 of 58), and their size ranged from 5 to 30 (mean, 17.5)mm. Pseudolesions were wedge-shaped (48 of 58), oval (6 of 58), bandlike (3 of 58), or round (1 of 58). CONCLUSION: CTAP and CTHA frequently revealed pseudolesion around the GB fossa. The radiological characteristics of these modalities help differentiate pseudolesions from true tumoral hepatic lesions.

Transurethral Exchange of Double-J Ureteral Stent Using Goose-Neck Snare

PURPOSE: To evaluate the usefulness of transurethral exchange of double-J ureteral stent as an effective alternative to the cystoscopic approach. MATERIALS AND METHODS: There were 20 exchange cases involving seven patients (six women and one man) who initially underwent antegrade manipulation of a double-J ureteral stent. Indications for stent placement were ureteral stricture caused by malignancy in six patients [cervical carcinoma (n=5), stomach carcinoma (n=1) ], and renal tuberculosis in one. An 8-F Nelaton catheter was inserted in the bladder via the urethra and contrast material was injected until the bladder was fully distended. The distal end of a double-J ureteral stent was extracted to the urethral orifice using a goose-neck snare and a 0.035 "stiff guide wire was then advanced to the renal pelvis through the stent. After that, the stent was removed and a 4-F Cobra catheter was advanced to the renal pelvis along the guide wire. Contrast material was injected through the catheter, and the renal pelvis, calyx and ureter were opacified. The 0.035 "stiff guide wire was again inserted via the catheter, a new double-J ureteral stent was inserted, and the catheter removed. Finally, the new double-J stent was properly located within the renal pelvis and the bladder. RESULTS: Double-J ureteral stents were successfully exchanged in 19 of 20 exchange cases. After the procedure, all patients reported tolerable, minimal lower abdominal pain. CONCLUSION: Transurethral exchange of double-J ureteral stent is a useful alternative to cystoscopy.

Zebra Pattern in CT during Arterial Portography: Analysis of Associated Factors

PURPOSE: To analyze the factors associated with the zebra pattern in CT during arterial portography(CTAP). MATERIALS AND METHODS: In 275 CTAP procedures, the factors associated with the zebra pattern, such as laminar flow in the portal vein, the presence of liver cirrhosis, the artery selected for CTAP, location of the catheter tip in the superior mesenteric artery(SMA), splenic volume, and the existence of an aberrant right hepatic artery(RHA) emerging from the SMA were analyzed. RESULTS: In 106 of 275 procedures (38.5%), a zebra pattern was apparent. Portal venous laminal flow was seen in 92 % of procedures in the group with this pattern and in 63 % in the group without it. Eighty-three of 235 procedures (35.3 %) in which the SMA was injected and 23 of 40(57.5 %) involving splenic artery injection showed the zebra pattern. In 22 of 35(62.8 %) in which the catheter tip was located in the distal SMA and 61 of 200 ( 30.5 %) in which this was at a proximal site, the zebra pattern was evident. Mean splenic volume was less in the group with the zebra pattern. The effect on the zebra pattern of liver cirrhosis and an aberrant RHA emerging from the SMA was not statistically significant. CONCLUSION: In CTAP, the incidence of the zebra pattern was 38.6%, and was related to laminal flow in the portal vein. The pattern is frequently seen in CTAP involving contrast injection via the splenic artery, distal location of a catheter tip in the SMA, and small splenic volume.

Assessment of Contrast-enhanced 3D Ultrafast Pulmonary MR Angiography Using Test Injection: Comparison betweenSingle Dose and Double Dose

PURPOSE: Contrast-enhanced 3-D ultrafast MR angiography is a widely accepted MR imaging technique for theevaluation of the carotid artery, aorta, renal artery, mesenteric artery and portal venous system. To esti-mateitsclinical usefulness, single -and double- dose contrast-enhanced 3-D ultrafast pulmonary MR angiography wasassessed after a timing examination was performed. MATERIALS AND METHODS: Twenty volunteers underwentgadolinium-enhanced ultrafast pulmonary MR angiog-raphy( 3-D FISP, TR[msec]/TE[msec]=5.0/2.0, with 25 degrees flipangle). In ten volunteers(single-dose injection group) pulmonary MR angiography was performed after theadminstration of 0.1 mmol/kg(single dose injec-tion group), while the other ten(double-dose injection group) eachreceived, prior to angiography, 0.2 m m o l / kg. In all cases, a timing examination was performed during axialturbo-FLASH imaging(TR/TE/TI=8.5/4.0/100, 1 0 degree flip angle) after injection of the same dose as that used forsubsequent contrast-enhanced pulmonary MR angiography. In both groups, overall image quality, pulmonary arteryvisibility and contrast-to-noise ratio of the pulmonary artery were assessed on the basis of images obtained.RESULTS: With regard to overall image quality, there was no significant statistical difference between the twogroups (P>0.05), and in both, depiction of the central and lobar pulmonary artery was excellent. As regardsdepiction of the segmental artery, the average grading of the single dose injection group was 2.83 +/- 0.32, that ofthe double dose injection group was 2.85 +/-0.3, with no statistical significance(P>0.05). With respect tocon-trast-to-noise ratio of the central, lobar, and segmental arteries, the best results were obtained by thedouble dose injection group(P<0.05). CONCLUSION: Although the contrast-to-noise ratio in the double-dose injectiongroup was better than that in the single-dose group, differences in overall image quality and pulmoanry arterydepiction were not statistically significant. Thus, single-dose, contrast-enhanced 3-D ultrafast pulmonary MRangiography can provide useful images in clinical trials.

Bronchiectasis with Decreased Attenuation Areas on HRCT: Correlation with Pulmonary Function Test

PURPOSE: To evaluate the relationship between type, extent, and associated decreased attenuation areas ofbronchiectasis, as seen on high-resolution CT (HRCT), and abnormalities on pulmonary function tests. MATERIALS AND METHODS: We retrospectively evaluated 34 patients with bronchiectasis, in whom inspiratory and expiratory HRCTscans and pulmonary function tests were performed. HRCT scans were reviewed for the type (cylindrical vs. cystic)and extent of bronchiectasis (number of segments), and the extent of decreased attenuation areas seen oninspiratory (number of segments and CT scores) and expiratory scans (CT scores). With regard to the type andextent of bronchiectasis and the extent of decreased attenuation areas, as seen on HRCT, three radiologistsreached a consensus. We evaluated the relationship between pulmonary function tests (FEV1, FVC, FEV1/FVC, MMEF)and HRCT findings using Pearson correlation coefficients and linear regression (PC-SAS). RESULTS: In all patientswith bronchiectasis there were areas of decreased attenuation, as seen on inspiratory and expiratory HRCT. Theextent of bronchiectasis showed strong positive correlation with the extent of decreased attenuation seen oninspiratory and expiratory HRCT (p < 0.001). On pulmonary function tests, the extent of bronchiectasis anddecreased attenuation correlated negatively with FEV1, FVC, FEV1/FVC and MMEF. Cystic bronchiectasis tended to bemore extensive than the cylindrical variety (12.2 vs 7.6 ; CT score:34.7 vs 15.6) and expiratory scans (CT score :38.1 vs 19.1) CONCLUSION: There is significant correlation between the extent of morphologic abnormality, as seenon HRCT, and the physiologic impairment of pulmonary function tests in patients with bronchiectasis and associateddecreased attenuation areas.

Estimation of the Probability of Malignancy in Solitary Pulmonary Nodules: Comparative Study of Conventional Interpretation Method and Bayesian Analysis

PURPOSE: The aim of this study was to compare the accuracy of the conventional method and Bayesian analysisin estimating the probability of malignancy in solitary pulmonary nodules. MATERIALS AND METHODS: The studyinvolved 83 pathologically proven cases of solitary pulmon ary nodules, 44 of which were malignant, and 39,benign. To estimate the probability of malignancy in solitary pulmonary nodules, chest radiographs and CT scans ofthe 83 patients were interpreted by a team of six ; three of the six used the conventional method of subjectiveinterpretation and the others. Bayesian analysis. The smoking history of 59 of the patients was obtained, and itwas decided whether this would help determine the probability of malignancy. RESULTS: On average, those using theconventional method correctly interpreted 34.7(78.9%) of 44 cases of malignant nodules and 27.7(71%) of 39 benignnodules, while those using Bayesian analysis correctly classified 32.3 cases of malignant nodules(73.4%) and 25.3cases of benign nodules(64.9%). Between the two teams, there was no statistically significant difference in theaccuracy of qualitative assessment(P>.05). In ROC analysis conventional interpretation and Bayesian analysisshowed an accuracy of Az=80.8 and Az=76.7, respectively. Among 59 patients known to have smoked, the conventionalmethod showed an accuracy of Az=79.0 without this knowledge and Az=80.2 with the knowledge for Bayesian analysis,the corresponding figures were Az=77.2 and Az=72.5, respectively. Information relating to smoking history thus didnot significantly improve the accuracy of prediction(p>.05). CONCLUSION: For estimating the probability ofmalignancy in solitary pulmonary nodules, the accuacy of the conventional method of interpretation is notsignificantly different from that of Bayesian analysis; information relating to smoking history significantlyimprove the accuracy of neither method.

Double Uncture fo Single Common Femoral Artery for CT Hepatic Arteriography and CT Arterial Portography

PURPOSE: To evaluate the safety and efficacy of double puncture of a single common femoral artery for CThepatic arteriography(CTHA) and CT arterial portography(CTAP) in patients with hepatocellular carcinoma. MATERIAL AND METHODS: Between October and December 1995, 35 patients with hepatocellular carcinoma underwent doublepuncture of a single common femoral artery for combined CTHA and CTAP. Preangiographic laboratory data were asfollows : platelet count from 28,000 to 250,000/mm3 (average, 124,500/mm3) ; prothrombin time from 45.8% to100%(average, 85.3%). In the inguinal area, a pair of 21G puncture needles were used unilaterally for the firsttwo femoral punctures, at a distance of 5-7mm ; a 0.018" guidewire for the insertion of a 4-F sheath in a coaxialmicropuncure introducer set ; and a 0.035" guidewire and 4 F check-flo sheath for the insertion of 4-F catheters.After being moved to the CT room, patients then underwent spiral CTHA and CTAP for further detection ofhepatocellular carcinoma nodules. Transarterial chemoembolization followed, and the punctured site was thencompressed by the usual finger compression method. After initial compression and one day later, we observed thepuncture site for complications such as hematoma formation, thromboembolization or arteriovenous fistula ; ect. RESULTS: Except for the formation of two mild hematomas, no remarkable severe complications were noted. Fifteenpatients who had previously undergone combined spiral CTHA and CTAP using the bilateral femoral puncture method(with a 5-F check-flo sheath) felt more comfortable than when an earlier method was used. CONCLUSION: For combinedCTHA and CTAP, double puncture of a single common femoral artery is safer and more comfortable than the bilateralfemoral puncture method.

Lung Cancer With CT-Bronchus Sign: Correlation with CT-findings and the Yield of Bronchoscopic Biopsy

PURPOSE: To determine the CT factors which predict positive results of bronchoscopic biopsy in cases of lung cancer with CT-bronchus sign. MATERIALS AND METHODS: In 30 patients who on CT showed a lung mass with CT-bronchus sign and who had undergone bronchoscopic biopsy, lung cancer was confirmed histopathologically and/or clinically. The CT findings were evaluated for the location, nature and size of the mass, and the type of CT-bronchus sign, and the diagnostic rate of bronchoscopic biopsy and of CT findings was compared. RESULTS: Seventeen of 30 patients (56.7%) were diagnosed by bronchoscopic biopsy and their diagnostic rates according to the location were as follows: 100% (10/10) in cases involving the lobar bronchus; 60% (6/10) in cases involving the proximal segmental bronchus and 10% (1/10) in cases involving the distal segmental bronchus. In 20 cases of peripheral lung cancer, 16.7% (1/6) of masses with less than 3cm in diameter, 44.4% (4/9) of masses with more than 3cm and less than 6cm, and 40.0% (2/5) of masses with more than 6cm were diagnosed bronchoscopically. In addition, 57.1% (4/7) of cases with abrupt bronchial obstruction, 33.3% (3/9) with a patent bronchus within the mass, 0% (0/3) with bronchial displacement or a marginally located bronchus and 0% (0/1) with tapered bronchial obstruction were diagnosed on bronchoscopic biopsy. One of two cases with perilesional lymphangitic spread and two of four cases with a large cavity were diagnosed bronchoscopically. CONCLUSION: In cases of lung cancer, bronchoscopic biopsy is a useful initial diagnostic method where the mass is located in 1cm proximal to segmental bronchial bifurcation and is more than 3cm in diameter, there is CT-bronchus sign with abrupt bronchial obstruction or a patent bronchus within the mass, and associated perilesional lymphangitic spread or large air-cavity. In most cases where there is peripheral lung mass less than 3cm in diameter, however, bronchoscopic biopsy alone is not adequate, and the use of a further diagnostic modality is required.

Hepatic Hemangioma: Findings of Spiral CTHA and CTAP

PURPOSE: To evaluate the characteristic finding of hepatic hemangioma on spiral CT during hepatic arteriography(CTHA) and arterial portography(CTAP). MATERIALS AND METHODS: Twenty-eight hepatic hemangionas inten patients were analyzed by spiral CTHA & CTAP, and were confirmed by US, conventional CT, MRI, and follow-upimages. Their sizes varied between 5 and 6cm(average 1.8cm) ; using CTHA and CTAP, enhancement patterns were analysed according to size, and on CTHA were found to be homogeneous hyperattenuating(HH), peripheral globular hyperattenuating(PG), and mixed(M) type. RESULTS: All hepatic hemangiomas showed perfusion defects on CTAP. OnCTHA, the PG type accounted for 16 of 28 hemangiomas(57%), the HH type for 7(25%), and the M type for 5(18%) ;CTHA also showed that 23 hemangiomas(82%) had an irregular enhanced margin. CONCLUSION: On CTHA, the most common characteristic finding of hepatic hemangioma was the peripheral globular enhancement pattern(57%). In the diagnosis of hepatic hemangioma accompanied by hepatocellular carcinoma or other liver metastasis, CTHA is more useful than CTAP ; in all cases the latter showed only perfusion defects.

Pattern Analysis of False Positive Findings of Spiral CT Hepatic Arteriography

PURPOSE: To evaluate the patterns of pseudo-lesions present on spiral CT hepatic arteriography (CTHA). MATERIALS AND METHODS: One hundred and seventy five patients (161 men and 14 women, aged 15-70 years [mean, 52 years]) who underwent spiral CTHA for the detection of hepatic lesions were retrospectively reviewed.Pseudo-lesion type was determined by comparing hyperattenuating lesions on CTHA with the findings of ultrasonography, conventional or multi-phase CT, Lipiodol CT, angiography, CT arterial portography(CTAP), and follow-up of spiral CTHA. Pseudo-lesions were classified according to site, size and shape. RESULTS: A total of 77 pseudo-lesions were found in 56 of the 175 patients(32.6%), and were classified into the following types :peritumoral(n=18), segment I(n=3), segment IV(n=3), gallbladder fossa (n=13), subsegmental (n=3), subcapsular(n=13), straight line sign (n=10), arterioportal shunt (n=13), and technical error (n=1). Fifteen of 77 pseudo-lesions(19.5%) showed hyperattenuation on CTHA and iso attenuation on CTAP, in contrast to adjacent liverparenchyma. CONCLUSION: In patients with hepatic mass, it is very important to understand the characteristicsite, shape and size of pseudo-lesions for the correct interpretation of CT and subsequent management of thepatient.

Acute Interstitial Pneumonia: HRCT Findings in Five Patients

PURPOSE: To describe HRCT findings in five patients with pathologically proved acute interstitial pneumonia MATERIALS AND METHODS: This study included 5 patients with pathological and clinical diagnosis of acute interstitial pneumonia. Mean age of the patients was 40(range, 31-53 years). CT scans were reviewed by two chest radiologists retrospectively. CT scans were assessed for the presence and distribution of ground-glass attenuation, air-space consolidation, interlobular septal thickening, honeycombing, and pleural effusion. RESULTS: The area of ground-glass attenuation and air-space consolidation were seen at HRCT in all 5 patients. These lesions were distributed diffusely in both lungs, but involved predominantly subpleural lungs in 2 patients and posterior lungs in 3 patients. Three patients had mild interlobular septal thickening. None of them showed honeycombing. Three of the 5 patients died within 52 days of initial manifestation. CONCLUSION: Acute interstitial pneumonia differs from the more chronic form of idiopathic interstitial pneumonia in their HRCT findings.

Pattern of Distant Lymph Node Metastasis in Colorectal Carcinoma and its Correlation with Distant Organ Metastasis: CT Evaluation

PURPOSE: To evaluate the pattern of distant lymph node metastasis in colorectal carcinoma and its correlation with distant organ metastasis. MATERIALS AND METHODS: We retrospectively reviewed abdominal CT scans of 46 patients with pathologically proven colorectal carcinoma. RESULTS: The incidence of distant lymphadenopathy in colorectal carcinoma was 30.4%(14/46). The most commonly involved distant lymph node was the left paraortic lymph node below the renal hilum(9/25). The most common type of distant lymphadenopathy was solitary type(7/14) and all of these lymphadenopathies were noted in the left paraortic lymph node below the renal hilum. Six cases of left sided colorectal carcinoma showed left paraortic lymphadenopathy with solitary type. The incidence of distant organ metastasis was 17. 4%(8/46) and markedly increased if distant lymphadenopathy was multiple and confluent, or confluent type(5/7). CONCLUSION: The incidence of distant lymphadenopathy in colorectal carcinoma was not high and the most common lymphadenopathy was the left paraaortic lymph node with solitary type below the renal hilum. The possibility of distant organ metastasis was high if distant lymphadenopathy was multiple and confluent, or confluent type.

High-Resolution CT Findings in Swyer-James Syndrome

PURPOSE: The purpose of this study was to evaluate the high-resolution CT features of Swyer-James syndrome with special attention to the airway lesions and to determine the clinical utility of high-resolution CT compared with that of chest radiography. MATERIALS AND METHODS: In seven patients with Swyer-James syndrome, we retrospectively reviewed chest radiographs obtained during inspiration and expiration and high-resolution CT scans obtained in inspiration. The high-resolution CT appearance was evaluated and compared with that of chest radiography. RESULTS: On both chest radiographs and high-resolution CT, the affected lung volume was relatively diminished in four patients and normal in three patients. In all seven patients, chest readiographs showed hyperlucency of the lung which was unilateral in four and bilateral in three patients. Unilateral small hilum was seen in six patients and bronchiectasis was demonstrated in one patient on chest radiographs. The hyperlucent lung volume was not diminished on expiratory radiographs in all seven patients. In all patients, high-resolution CT demonstrated low attenuation regions of the lung either bilaterally(n=5) or unilaterally(n=2). Pulmonary vessels were markedly decreased in size and number in the lung parenchyma with low attenuation. Six patients had bronchiectasis on high-resolution CT, which were cylindrical or varicose in five and cystic in one. Bronchiolectasis was observed in three patients on high-resolution CT. CONCLUSION: The high-resolution CT findings are characteristic of Swyer-James syndrome. High-resolution CT is more sensitive than chest radiography in detecting regions of low attenuation and bronchiectasis and may be useful for the diagnosis of Swyer-James syndrome. Our results suggest that bronchiectasis is a frequently associated airway lesion of Swyer-James syndrome and bronchiolectasis may be associated in some cases.

Plexiform Neurofibromatosis of the Mediastinum: CT Findings

PURPOSE: To evaluate the findings and the role of CT in plexiform neuro-fibromatosis of the mediastinum. MATERIALS AND METHODS: We retropectively reviewed the CT scans of five patients with plexiform neurofibromatosis of the mediastinum. The CT scans were reviewed with attention to the distribution of the lesions, appearance and attenuation of mediastinal lesions, enhancement pattern after intravenous contrast infusion and associated findingssuch as intercostal neurofibroma. RESULTS: In all five patients CT scans demonstrated fusiform low attenuated masses which were oriented longitudinally and extended over multiple contiguous scans along the distribution of major mediastinal nerves. In four patients, mediastinal lesions appeared infiltrative, obliterating adjacent mediastinal fat plane. One patient had well defined fusiform masses along the major mediastinal nerves. Postcontrast enhanced CT scans revealed slight central enhancement in two patient and no contrast enhancement in three patients. Associated findings such as neurofibromas of intercostal nerves and sympathetic trunk, or subcutaneous neurofibromas were detected on CTscans in all five patients. CONCLUSION: Characteristic CT findings of low attenuation masses along the major mediastinal nerves are helpful to differentiate plexiform neurofibromatosis from mediastinal lymphadenopathy and to prevent from misreading as a malignant disease.

An Experimental Study on Mixing of Chemoembolic Material for Hepatocellular Carcinoma

PURPOSE: The chemoembolization with Lipiodol and doxorubicin hydrochloride is used in patients with hepatocellular carcinoma. What condition is the ideal emulsion of Lipiodol and doxorubicin for excellent anticancer effect? METHOD AND MATERIALS: Microscopic evaluation was performed on the emulsions, which were varied with different specific gravities of doxorubicin solutions, degrees in mixing of the emulsion, and amount of Lipiodol. RESULT: 1. Maximal amount of doxorubicin solution was contained in Lipiodol droplets and the release of doxorubicin from the droplets were delayed, when specific gravity of doxorubicin was equal to that of Lipiodol (SG, 1.28). 2. The optimal therapertic ratio of Lipiodol and doxorubicin was 3:2 at least, as in the emulsion less than 3:2, unmixed free forms of doxorubicin solution were increased. 3. The emulsion mixed by pumping 50--100 times had smaller Lipiodol droplets and contained larger amount of doxorubicin solution in the droplets than by pumping 20 times. CONCLUSION: We recommend the emulsion with specific gravity of doxorubicin equal to Lipiodol (SG. 1.28), the ratio of Lipiodol and doxorubicin closo to 3:2, and the mixture prepased with puming 50--100 times.