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.

Anatomical Relationship between the Optic Nerve and Posterior Paranasal Sinuses on Ostiomeatal Unit CT

PURPOSE: To determine the anatomic variations that can lead to optic nerve damage during the sugical treatment of posterior paranasal sinus lesions MATERIALS AND METHODS: two hundred optic nerves of 100 persons were examined using ostiomeatal unit CT (OMU CT). The anatomical features of this nerve and posterior paranasal sinuses were classified into four types : the optic nerve adjacent to the sphenoid sinus without indentation of the sinus wall (type 1); the optic nerve adjacent to the sphenoid sinus, causing indentation of the sinus wall (type 2); the optic nerve passing through the sphenoid sinus (type 3); and the optic nerve adjacent to the sphenoid sinus and posterior ethmoid sinus (type 4). Bony dehiscence around the optic nerve and pneumatization of the anterior clinoid process were also evaluated. RESULTS: The anatomical classification of the optic nerve and posterior paranasal sinuses was as follows : type 1, 1326 (66%); type 2, 60 (30%); type 3, 6 (3%), and type 4, 2 (1%). Bony dehiscence around the optic nerve had developed in 58 cases (29%) and pneumatization of the anterior clinoid process in 13 (6.5%). These conditions were most common in type 3 optic nerve, and second most common in type 2. CONCLUSION: The 2 and 3 optic nerve, bony dehiscence around the optic nerve and pneumatization of the anterior clinoid process are the anatomic variations that can lead to optic nerve damage during the surgical treatment of posterior paranasal sinus lesions. To prevent optic nerve damage, these factors should be carefully evaluated by OMU CT.