Cystic changes in intraabdominal extrahepatic metastases from gastrointestinal stromal tumors treated with imatinib

Small submucosal tumors of the stomach: differentiation of gastric schwannoma from gastrointestinal stromal tumor with CT

Objective

To identify the CT features that help differentiate gastric schwannomas (GS) from small (5 cm or smaller) gastrointestinal stromal tumors (GIST) and to assess the growth rates of both tumors.

Materials and Methods

We included 16 small GSs and 56 GISTs located in the stomach. We evaluated the CT features including size, contour, surface pattern, margins, growth pattern, pattern and degree of contrast enhancement, and the presence of intralesional low attenuation area, hemorrhage, calcification, surface dimpling, fistula, perilesional lymph nodes (LNs), invasion to other organs, metastasis, ascites, and peritoneal seeding. We also estimated the tumor volume doubling time.

Results

Compared with GISTs, GSs more frequently demonstrated a homogeneous enhancement pattern, exophytic or mixed growth pattern, and the presence of perilesional LNs (each p < 0.05). The intralesional low attenuation area was more common in GISTs than GSs (p < 0.05). Multivariate analyses indicated that a homogeneous enhancement pattern, exophytic or mixed growth pattern, and the presence of perilesional LNs were statistically significant (p < 0.05). Tumor volume doubling times for GSs (mean, 1685.4 days) were significantly longer than that of GISTs (mean, 377.6 days) (p = 0.004).

Conclusion

Although small GSs and GISTs show similar imaging findings, GSs more frequently show an exophytic or mixed growth pattern, homogeneous enhancement pattern, perilesional LNs and grow slower than GISTs.

Change in contrast enhancement of HCC on 1-month follow-up CT after local radiotherapy: an early predictor of final treatment response

BACKGROUND

The purpose of this study was to evaluate the change in contrast enhancement of HCC on 1-month follow-up CT after local radiotherapy (RT) as an early predictor of final treatment response.

MATERIALS

Fifty patients who underwent local RT for HCCs had both pre-RT and post-RT CT scans including 1-month follow-up CT. We assessed the final treatment response by using the change in maximal tumor size on 6-12-month follow-up CT scan after RT. We also evaluated the change in tumor enhancement between pre-RT and 1-month follow-up CT scans.

RESULTS

A final treatment response was achieved in 27 (54%) of 50 patients, who showed either a complete response (n=11) or a partial response (n=16). Compared with non-responsive patients (n=23), responsive patients showed a significant decrease in tumor enhancement on 1-month follow-up CT after RT in both objective and subjective analyses (each P<0.001).

CONCLUSION

The change in contrast enhancement of HCC seen on the 1-month follow-up CT in patients after local RT may be used as an early predictor of final treatment response.

Assessment of gastrointestinal stromal tumors with computed tomography following treatment with imatinib mesylate

AIM: To evaluate and characterize the patterns of disease progression of metastatic or unresectable gastrointestinal stromal tumor (GIST) treated with imatinib mesylate, and to determine the prognostic significance associated with disease progression.

METHODS: Clinical data and computed tomography (CT) images were retrospectively reviewed in 17 GIST patients who were treated with imatinib mesylate from October 2002 to October 2006. Apart from using size measurement for evaluation of tumor response [Response Evaluation Criteria in Solid Tumors (RECIST) criteria], patterns of CT changes during treatment were evaluated and correlated with clinical data.

RESULTS: There were eight non-responders and nine responders. Five patterns of CT change during treatment were found: focal progression (FP), generalized progression (GP), generalized cystic change (GC), new cystic lesion (NC) and new solid lesion (NS). At the end of study, all non-responders showed GP, whereas responders showed cystic change (GC and NC) and response according to RECIST criteria. Overall survival was significantly better in patients with cystic change or response within the RECIST criteria compared with GP patients (P = 0.0271).

CONCLUSION: Various patterns of CT change in patients with GIST who responded to imatinib mesylate were demonstrated, and might determine the prognosis of the disease. A combination of RECIST criteria and pattern of CT change are proposed for response evaluation in GIST.

Computed Tomography and Sonographic Findings of Hepatic Metastases From Gastrointestinal Stromal Tumors After Chemotherapy

OBJECTIVE

The purpose of this study was to evaluate the computed tomography (CT) and sonographic findings in patients with hepatic metastases from gastrointestinal stromal tumors (GISTs) after STI-571 treatment.

METHODS

Computed tomography and sonographic findings of 8 lesions in 6 patients with hepatic metastases from GISTs that were treated with STI-571 were retrospectively analyzed. The change in size, attenuation, and echogenicity of the hepatic metastases from GISTs after STI-571 treatment was evaluated.

RESULTS

After treatment with STI-571, the hepatic metastases were decreased in size and the attenuation of the hepatic metastases was homogeneously hypodense on CT. Sonography revealed the hepatic metastases to be centrally cystic with a thin wall (n = 4) or predominantly solid (n = 4) after STI-571 treatment. On color Doppler sonography, no blood flow was identified within the solid portion of the mass.

CONCLUSION

After treatment with STI-571, although the hepatic metastases from GISTs exhibit a cystic appearance on CT, they may appear as solid masses on sonography.