Three Phase Dynamic CT with Double Spiral CT: Utility of Determination of Stomach Cancer Stage

PURPOSE: To evaluate the utillity of three phases of spiral CT in the diagnosis of stomach cancer. MATERIALS AND METHODS: Between August 1994 and March 1995, thirty eight patients with stomach cancer, demonstrated on spiral CT, underwent surgery. Twenty-eight cases were advanced and ten were early. There were 27 men, and 11 women, and their average age was 52.8 years old (33-77). After ingestion of 600 - 700ml of water, 120 - 140ml of nonionic contrast material was injected intravenously. Spiral CT scanning was performed in 10mm slice thickness and of 10 mm/sec table speed. Three phase images were obtained at 25 sec (arterial phase), 60-65 sec (venous phase) and 4min (equilibrium phase) after the start of bolus injection. On each phase, CT findings were compared with pathologic results, and tumor detectibility, depth of tumor invasion and lymph node metastasis was analysed. RESULTS: Thirty of the 38 carcinomas (79%) were detected on the arterial phase, 33 (81%) on the venous phase and 30 (79%) on the equilibrium phase. Depth of tumor invasion was measured accurately in 27 of 38 cases (71%): T1 -4/10 (40%), T2 - 8/11 (73%), T3 - 13/15 ( 87% ), T4 - 2/2 ( 100% ). We overstaged one case of T1 as T2 and two cases of T2 as T3, and understaged one case of T2 as T1 and two cases of T3 as T2. Among the 16 enlarged lymph nodes larger than 8mm, 13 cases were positive on pathologic examination and the sensitivity was 65%. CONCLUSION: With three-phase spiral CT scanning, we obtained 71% accuracy of depth of tumor invasion. The venous phase is most useful for tumor detection and for determining depth of tumor invasion and lymph node metastasis.

Triple Phase Spiral CT Findings of Hepatocellular Carcinoma

PURPOSE: To evaluate contrast enhancement patterns of hepatomas (HCCs) on arterial dominant, portal dominant,and delayed phase of CT scan by using double spiral CT. MATERIALS AND METHODS: Using double-spiral CT, three-phase dynamic liver scan was performed on 27 patients with 45 nodular HCC lesions. Non-ionic contrast medium(100-120ml) was injected intravenously with an automatic injector at the rate of 2-4 ml/sec. CT scans were obtained at 25-30sec (arterial dominant phase), 60 sec (portal dominant phase), and 5min (delayed phase) afteradministration of the contrast medium. The tumor were divided into two groups according to the diameter( or = 3cm). In each group, contrast enhancement patterns of HCCs were classified as follows : high, central high, peripheral high, iso, low, or mixed attenuation. The incidence and contrast enhancement patterns of thin peripheral rims(psevdocapsules) were also analyzed. RESULTS: There were 23 lesions with a diameter less than 3cm,while 22 lesions were 3cm or larger. On the arterial dominant phase, tumors smaller than 3cm showed high(74%), iso(17%), mixed(4%), and peripheral high(4%) attenuation, while the attenuation of tumors larger than 3cm washigh(73%), mixed(9%), iso(9%), and low(9%). On the portal dominant phase, tumors smaller than 3cm were mostcommonly iso(43%) or high(35%), while tumors larger than 3cm were low(65%) or iso(18%). On the delayed phase, tumors were most commonly low in attenuation regardless of size. A thin peripheral rim was observed in 22% of tumors smaller than 3cm and in 64% of tumors larger than 3cm. The rim showed iso(53%) or low(42%) attenuation onthe arterial dominant phase, high(47%) or iso(47%) attenuation on the portal dominant phase, and high(100%) attenuation on the delayed phase. CONCLUSIONS: For the detection and diagnois of HCCS, an understanding of their contrast enhancement patterns is useful.

Differential Diagnosis of Solitary Pulmonary Nodule: Chest Radiography vs CT

PURPOSE: The purpose of this study was to compare the diagnostic accuracies of chest radiographs and chest CTin the diagnosis of a solitary pulmonary nodule(SPN), and to determine the role of CT and CT findings which aid inthe differential diagnosis of nodules. MATERIALS AND METHODS: A retrospective study was done on 54 patients inwhom SPN was found on chest radiographs and chest CT was carried out. The study involved 25 benign and 29 malignant nodules, confirmed histopathologically and clinically. Chest radiographs and CT scans were reviewed separately in randomized order by two chest radiologists who for each film listed the three most likely diagnose sin descending order. The radiologists recorded the confidence value of the most probable diagnosis, and also the marginal and internal characteristics of nodules and their size, as nodules seen on chest CT scans. RESULTS: Diagnostic rates in the differential diagnosis of benign and malignant nodules were 65.7% by radiography and 77.8% by CT. Correct first-choice diagnosis was by radiography in 30.6 % of cases, and by CT in 41.7%. Using radiographs, and the correct diagnosis was among the top-three choices in 61.1% of cases ; with CT, the corresponding figure was 76.8%. Overall, a confident diagnosis was reached more often with the CT(41.7%) than with the chest radiograph(21.4%) ; diagnaotic accuracy was 60.0% and 52.2%, respectively. CT findings which imply abenign nodule include smooth margins and diffuse internal calcifications, whereas marginal lobulations, air-bronchograms, internal low density without cavitation, eccentric calcifications, and large size suggest malignancy. We faund that CT findings such as well-defined margins, spiculations, pleural tail or internal homogeneity did not contribute in the differentiation between benign and malignant nodules. CONCLUSION: CT issuperior to chest radiography in the differential diagnosis of the solitary pulmonary nodule. Using CT, diagnosis was accurate and made with a high level of confidence, especially with the application of CT findings which aid inthe differential diagnosis of nodules.