CT evaluation of treatment response in advanced gastric cancer

Usefulness of the non-distension of the stomach in the evaluation of perigastric invasion in advanced gastric cancer by CT

The purpose of this study was to evaluate by CT the usefulness of the non-distension of the stomach in determining invasion of the gastric cancer into perigastric space and adjacent organs. Forty-eight patients with pathologically proved gastric cancer were studied by conventional CT. Patients were examined using two techniques: (a) non-distension of the stomach in the supine position and 34 patients additionally in prone position; and (b) distension of the stomach with water or air in the supine and/or prone position. CT findings by both techniques were separately analysed preoperatively and compared to surgical findings. Invasion of perigastric fat was better demonstrated by the non-distension technique in 15 of the 36 patients with pathologically proven fat infiltration. Non-distension technique was more accurate than distension in detecting: (a) involvement of gastric ligaments (80 versus 67% for gastrohepatic, 85 versus 73% for gastrocolic and 80% by both techniques for gastrosplenic ligament); (b) perigastric lymphadenopathy (86% by both techniques for lymph nodes sited at the gastrohepatic ligament, 85 versus 75% for gastrocolic and 85 versus 80% for gastrosplenic ligament lymph nodes, respectively); and (c) pancreatic invasion (86 versus 80%). The prone position with non-distended stomach was particularly helpful in excluding pancreatic invasion in five patients with carcinoma of the gastric body. The distension technique was more accurate in demonstrating perigastric extension in gastroesophageal junction tumors in two patients. In conclusion, additional CT of the non-distended stomach with the patient in prone position can provide further evidence about infiltration of the perigastric fat, ligaments, lymph nodes and pancreas, in patients with gastric carcinoma, with the exception of gastroesophageal junction tumors.

CT of calcified liver metastases in colorectal carcinoma

PURPOSE

To assess the incidence, characteristics and prognostic significance of calcification within colorectal hepatic metastases.

MATERIALS AND METHODS

A retrospective analysis of CT in 265 patients with locally advanced or metastatic cancer was performed. Four groups were defined: (a) calcification within liver metastases prior to therapy, (b) noncalcified liver metastases with development of calcification on therapy, (c) noncalcified liver metastases, and (d) advanced local tumour without liver metastases. The number of calcified deposits in each patient was documented. A marker lesion was analysed for character, distribution and percentage of calcification. Survival between the four groups was compared.

RESULTS

Twenty-nine (11%) patients had calcified liver metastases at presentation and 10 (4%) developed calcification during chemotherapy. Analysis of a marker lesion showed that the most frequent characteristic was fine calcification with a variable distribution. The most frequent change on treatment was alteration in the extent of calcification. Calcification developing on treatment was usually central. There was no difference in survival between groups 1, 2 and 3, but groups 1, 2 and 3 had a shorter survival than group 4.

CONCLUSION

Calcification of liver metastases shows a variable pattern and may develop or change during therapy. Liver metastatic calcification may not carry any prognostic significance in colorectal cancer.

Correlation of CT with histopathological findings in patients with gastric and gastro-oesophageal carcinomas following neoadjuvant chemotherapy

Gastric carcinoma is the fourth commonest cause of death from malignant disease in United Kingdom. In the Western hemisphere, it usually presents with advanced disease, which contributes to its very poor prognosis. Pre-operative (neoadjuvant) chemotherapy offers the possibility of down-staging such tumours and the potential to render tumours operable. Computed tomography (CT) plays a central role in the assessment of patients presenting with the disease, and in those who undergo chemotherapy, in evaluating their response.

OBJECTIVE

This study was undertaken to evaluate the role of CT in predicting loco-regional spread of tumour following neoadjuvant chemotherapy in non-metastatic gastric and gastro-oesophageal cancers.

METHODS AND MATERIALS

We correlated CT evidence of loco-regional spread with pathological findings following surgery in 21 patients who received pre-operative chemotherapy.

RESULTS

Residual masses were seen on CT in 19 patients, and 15 contained active tumour, although in four patients no viable tumour was demonstrated at histopathology. The overall accuracy of CT in assessing loco-regional disease was disappointing with sensitivities, specificities, positive and negative predictive values of 57%, 43%, 75% and 33%, respectively.

CONCLUSIONS

We conclude that CT is not accurate in identifying residual loco-regional spread and therefore should not preclude surgery in those patients who have received neoadjuvant chemotherapy.