Well-Differentiated Hepatocellular Carcinoma: Triple-Phase Helical CT Findings

PURPOSE: To determine the imaging characteristics of well-differentiated hepatocellular carcinomas (HCCs), as seen at triple-phase helical CT. MATERIALS AND METHODS: Thirty-eight well-differentiated HCCs in 29 patients who underwent surgical resection comprised our study population. Triple-phase helical CT images were obtained at 30 seconds, 70 seconds, and 3 minutes after contrast injection, and HCCs were divided into four groups according to their size: smaller than 1 cm (n=12), 1-2 cm (n=15), 2-4 cm (n=8), and larger than 4 cm (n=3), The enhancement patterns of HCCs at triple-phase helical CT were retrospectively analysed. RESULTS: In the smaller than l cm group, the most common enhancement pattern at all three phases was iso-attenuation (n=8; 67%). In the 1-2 cm group, iso-attenuation (n=10; 67%) was most common during the arterial phase and slightly low attenuation during the portal and equilibrium phases while in the 2-4 cm group, high attenuation (n=6; 75%) was most common during the arterial and portal phases, and low attenuation during the equilibrium phase (n=6; 75%). Two (67%) of three cases in the larger than 4 cm group demonstrated low, including fatty, attenuation. The detection rate was 33% (4/12) in the smaller than 1 cm group, 87% (13/15) in the 1-2 cm group and 100% (11/11) in the 2-4 cm and larger than 4 cm groups. CONCLUSION: At triple-phase helical CT, the enhancement patterns of well-differentiated HCCs were diverse, and the detection rate of those larger than 1 cm was 92% (24/26).

Normal Development of Sutures and Synchondroses in the Central Skull Base: CT Study

PURPOSE: To evaluate the developmental patterns of the sutures and synchondroses in the central skull base. MATERIALS AND METHODS: We evaluated the CT scans of 109 children(age range, 29 days to 15 years) with no skull base abnormality who had undergone axial CT of the skull base with 1-mm collimation. Using a five-tier scheme, we analyzed the developmental patterns of the 18 sutures and synchondroses related to the sphenoid and occipital bones. RESULTS: Fusion of the sutures and synchondroses related to the sphenoid bone progressed rapidly during the first two years. Thereafter, changes in the sphenoid bone were dominated by pneumatization of the sphenoid sinus. Fusion of the synchondroses within the sphenoid body, including intersphenoidal, intrapresphenoidal, and intrapostsphenoidal synchondrosis occurred early and in most cases was graded <=4. Fusion of the sphenosquamosal, sphenoethmoidal, and frontosphenoidal sutures was delayed, and residual sclerosis was a common finding. Except for Kerckring-supraoccipital synchondrosis, fusion of the six sutures and synchon-droses related to the occipital bone occurred more gradually than that of those related to the sphenoid bone. Among these, fusion of the occipitomastoidal suture and petro-occipital synchondrosis was the last to occur. CONCLUSION: A knowledge of the developmental patterns of sutures and synchondroses can help differentiate normal conditions from those such as fracture, osseous dysplasia, or congenital malformation, which are abnormal. Our results provide certain basic informations about skull base maturity in children.

CT of Normal Variations of the Minute Central Skull Base Foramina

PURPOSE: To evaluate the CT appearance of normal variations in the minute central skull base foramina in infants and children. MATERIALS AND METHODS: One hundred and fourteen children under the age of 17 years without skull base abnormality underwent CT scanning. A high spatial frequency algorithm was used, and contiguous axial scanning parallel to the orbitomeatal line was performed from the foramen magnum to the orbital roof, with a 1-mm slice thickness. The presence or absence of eight foramina, pseudoforamina, or ossification centers including anterior presphenoidal foramen, posterior presphenoidal foramen, rostro-orbital pseudoforamen, intralateromedial postsphenoidal pseudoforamen, intrapostsphenoidal pseudoforamen, spheno-occipital pseudo-foramen, canalis basilaris medianus and intrasynchondral ossified bodies was analysed according to age. The presence of foramina or pseudoforamina was indicated if a ring-shaped structure was seen on two or more CT scans at the location anatomically predicted, and intrasynchondral ossified bodies were indicated if linear or dot-like structures with high attenuation accompanied spheno-occipital synchondrosis. RESULTS: CT indicated that within a certain age range, various kinds of foramina, pseudoforamina, and ossification centers were frequent. The anterior presphenoidal foramen was most commonly seen in infants aged 1-12 months (16/17, 94 %); the posterior presphenoidal foramen in children less than 2 years old(27/37, 73 % ) ; the rostro-orbital pseudoforamen in children aged 2 -5 years (9/17, 53%); intrapostsphenoidal pseudoforamen in children 6 -12 years old(20/37, 54%) and spheno-occipital pseudoforamen and intrasynchondral ossified bodies in children aged 13 -16 years. The canalis basilaris medianus was identified in about 20 % of all subjects regardless of age. CONCLUSION: Development of the minute central skull base foramina varied greatly according to age. Knowledge of the CT appearances of such embryologic variants of the central skull base should not only help Provide an understanding of complex skull base anatomy but also identify abnormal skull base development.

Usefulness of Flexible Covered Stent in Malignant Colorectal Obstruction

PURPOSE: To evaluate the usefulness of flexible covered stent in the treatment of acute colorectalobstruction secondary to colorectal carcinoma. MATERIALS AND METHODS: Flexible covered stents were placed in 11patients with clinical and radiologic signs of acute colonic obstruction secondary to colorectal carcinoma. Thepurposes of stent insertion were pre-operative bowel preparation in seven patients and palliative treatment infour. A fistula was present in two;in one this was between the proximal jejunum and colon, and the other wasrectovaginal. The usefulness of stent insertion for the purpose of preoperative bowel preparation was evaluatedaccording to the feasability and status of bowel preparation, as decided by the operator. Palliative treatment forthe relief of symptoms of acute bowel obstruction was evaluated according to the number and amount of defecation,bowel dilatation in simple abdomen radiography, and the presence of complications. RESULT: Bowel preparation forthe purpose of preoperative bowel cleansing was easy in seven patients;the fecal materials remaining in the colonpresented no problems during surgery. In one of four patients palliative treatment involved a colostomy;this wasdue to recurrent stent obstruction by fecal materials after three months, and in two other patients there wasstent obstruction after two and five months, respectively. The stent in one of four patients who underwentpalliative treatment was removed because of stent migration three days after insertion;the stents in two patientswith fistulas covered the fistulas successfully. Complications after stent insertion were anal pain in threepatients, anal bleeding in three and stent migration in one. CONCLUSION: The flexible covered stent was aneffective device for the relief of acute colonic obstruction secondary to malignant rectosigmoid neoplasia. Itallowed for single-stage operation and covered the fistula. We believe however that for further evaluation of theusefulness of this type of stent in long-term palliative treatment, a larger-scale study is needed.