OBJECTIVE: We aimed to describe radiologic signs and time-course of imatinib-associated fluid retention (FR) in patients with gastrointestinal stromal tumor (GIST), and its implications for management. MATERIALS AND METHODS: In this Institutional Review Board-approved, retrospective study of 403 patients with GIST treated with imatinib, 15 patients with imaging findings of FR were identified by screening radiology reports, followed by manual confirmation. Subcutaneous edema, ascites, pleural effusion, and pericardial effusion were graded on a four-point scale on CT scans; total score was the sum of these four scores. RESULTS: The most common radiologic sign of FR was subcutaneous edema (15/15, 100%), followed by ascites (12/15, 80%), pleural effusion (11/15, 73%), and pericardial effusion (6/15, 40%) at the time of maximum FR. Two distinct types of FR were observed: 1) acute/progressive FR, characterized by acute aggravation of FR and rapid improvement after management, 2) intermittent/steady FR, characterized by occasional or persistent mild FR. Acute/progressive FR always occurred early after drug initiation/dose escalation (median 1.9 month, range 0.3-4.0 months), while intermittent/steady FR occurred at any time. Compared to intermittent/steady FR, acute/progressive FR was severe (median score, 5 vs. 2.5, p = 0.002), and often required drug-cessation/dose-reduction. CONCLUSION: Two distinct types (acute/progressive and intermittent/steady FR) of imatinib-associated FR are observed and each type requires different management.
Adult ; Aged ; Aged, 80 and over ; Antineoplastic Agents/*adverse effects/therapeutic use ; Ascites/pathology/radiography ; Benzamides/*adverse effects/therapeutic use ; Echocardiography/methods ; Edema/pathology/radiography ; Female ; Gastrointestinal Stromal Tumors/drug therapy/pathology/*radiography ; Gastrointestinal Tract/pathology/*radiography ; Heart Failure/radiography ; Humans ; Male ; Middle Aged ; Molecular Targeted Therapy/*adverse effects ; Pericardial Effusion/pathology/radiography ; Peritoneal Neoplasms/diagnosis/radiography/secondary ; Piperazines/*adverse effects/therapeutic use ; Pleural Effusion/pathology/radiography ; Pyrimidines/*adverse effects/therapeutic use ; Radiology ; Retrospective Studies ; Tomography, X-Ray Computed

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.
Adult ; Aged ; Aged, 80 and over ; Contrast Media/diagnostic use ; Diagnosis, Differential ; Endoscopy, Gastrointestinal ; Female ; Gastrointestinal Stromal Tumors/pathology/*radiography ; Humans ; Iohexol/analogs & derivatives/diagnostic use ; Logistic Models ; Male ; Middle Aged ; Neurilemmoma/pathology/*radiography ; Retrospective Studies ; Statistics, Nonparametric ; Stomach Neoplasms/pathology/*radiography ; Tomography, X-Ray Computed/*methods

Imatinib, the first-line treatment in patients with advanced gastrointestinal stromal tumors (GIST), is generally well tolerated, although some patients have difficulty tolerating the standard dose of 400 mg/day. Adjusting imatinib dosage by plasma level monitoring may facilitate management of patients who experience intolerable toxicities due to overexposure to the drug. We present two cases of advanced GIST patients in whom we managed imatinib-related toxicities through dose modifications guided by imatinib plasma level monitoring. Imatinib blood level testing may be a promising approach for fine-tuning imatinib dosage for better tolerability and optimal clinical outcomes in patients with advanced GIST.
Aged ; Antineoplastic Agents/blood/*therapeutic use ; Benzamides/blood/*therapeutic use ; Drug Monitoring ; Exons ; Gastrointestinal Neoplasms/*drug therapy/pathology/radiography ; Gastrointestinal Stromal Tumors/*drug therapy/pathology/radiography ; Humans ; Liver Neoplasms/secondary ; Male ; Mutation ; Piperazines/blood/*therapeutic use ; Positron-Emission Tomography ; Proto-Oncogene Proteins c-kit/genetics ; Pyrimidines/blood/*therapeutic use ; Tomography, X-Ray Computed

OBJECTIVE: This study was undertaken for the purpose of describing the CT features of intra-abdominal extra-hepatic metastases from gastrointestinal stromal tumors in patients who were treated with imatinib. MATERIALS AND METHODS: Eleven patients with intra-abdominal extra-hepatic metastases from gastrointestinal stromal tumors, who were treated with imatinib between May 2001 and December 2003, were included in this study. The clinical findings and CT scans were retrospectively reviewed. The metastatic lesions were assessed according to the location, size (greatest diameter), attenuation, and the enhancing pattern before and after imatinib treatment. RESULTS: Prior to the treatment, the sizes and attenuation values of the metastatic lesions ranged from 5 to 20 cm and from 63 to 131 H, respectively. The metastatic lesions showed a heterogeneous enhancement pattern on the contrast-enhanced CT scans. After the treatment, the metastatic lesions became smaller in all 11 patients, and the corresponding attenuation value ranged from 15 to 51 H. The metastatic lesions became homogeneous and cystic in appearance on the follow-up CT scans, mimicking ascites. CONCLUSION: Intra-abdominal extra-hepatic metastases of patients with gastrointestinal stromal tumors treated with imatinib may appear as well-circumscribed cystic lesions on contrast-enhanced CT. These metastases are likely to become smaller and resemble ascites, but may persist indefinitely on the follow-up CT.
Adult ; Aged ; Antineoplastic Agents/*therapeutic use ; Contrast Media ; Gastrointestinal Stromal Tumors/*pathology/surgery ; Humans ; Iohexol/*analogs & derivatives/diagnostic use ; Liver Neoplasms/drug therapy/*radiography/secondary ; Male ; Middle Aged ; Peritoneal Neoplasms/drug therapy/*radiography/secondary ; Piperazines/*therapeutic use ; Protein-Tyrosine Kinase/antagonists & inhibitors ; Pyrimidines/*therapeutic use ; Research Support, Non-U.S. Gov't ; Retrospective Studies ; Tomography, X-Ray Computed/methods