Suvipapun Worawattanakul

Cholangiocarcinoma: Spectrum of appearances on mr images using current techniques

This study describes the spectrum of appearances of cholangiocarcinoma on magnetic resonance (MR) sequences, including gadolinium-enhanced, fat-suppressed spoiled gradient echo images and MR cholangiography. Fifteen patients were included in the study. Histologic diagnosis was established in 11 patients by surgical resection (6 patients), percutaneous biopsy (4 patients), and open liver biopsy (1 patient). The final diagnosis was determined by correlation of the MR findings with cholangiographic studies and laboratory studies in 4 patients. MR studies were performed at 1.5 T, and the following sequences were obtained: T1-weighted spoiled gradient echo (SGE), T1-weighted fat-suppressed spin echo or SGE, T2-weighted fat-suppressed conventional or turbo spin echo, MR cholangiography, and gadolinium-enhanced T1-weighted fat-suppressed SGE images. The following determinations were made: tumor location, tumor extent, ductal dilatation, ductal wall thickness, signal intensity, enhancement pattern, and associated findings. Mass-like neoplasms were peripheral (6 patients), hilar (1 patient), and extrahepatic (2 patients). Circumferential tumors were hilar (2 patients) and extrahepatic (4 patients). All peripheral tumors were multifocal. Mass-like tumors were well-defined, rounded, and ranged from 1 to 14 cm in diameter. Circumferential tumors had less well-defined margins and measured from 3 to 15 mm in thickness. All mass-like tumors were moderately hypointense on T1-weighted images and mildly to moderately hyperintense on T2-weighted images. The circumferential tumors were iso- to moderately hypointense on T1-weighted images and iso- to mildly hyperintense on T2-weighted images. Mass-like tumors were generally well shown on non-contrast and immediate gadolinium-enhanced images, whereas circumferential tumors were poorly seen on non-contrast images and best shown on gadolinium-enhanced T1-weighted fat-suppressed images. The degree of enhancement ranged from minimal to intense on immediate gadolinium-enhanced images, with all tumors becoming more homogeneous in signal intensity on images obtained between 1 and 5 min following contrast administration. Tumor-containing lymph nodes greater than or equal to 1 cm in diameter were demonstrated in 11 out of 15 patients (73.3%). These were best shown on T2-weighted fat-suppressed images and gadolinium-enhanced fat-suppressed SGE images. MR cholangiography demonstrated the level of obstruction and degree of dilatation of the proximal biliary system in 5 out of 6 patients who underwent MR cholangiography. The spectrum of appearances of cholangiocarcinoma is demonstrable on MR images. Mass-like tumors are well shown on both pre- and post-gadolinium sequences. Circumferential tumors may cause minimally increased duct wall thickness and are most clearly shown on gadolinium-enhanced fat-suppressed SGE images obtained 1 to 5 min following gadolinium administration.

Magnetic resonance imaging of neuroblastoma using current techniques

We evaluated the ability of current magnetic resonance (MR) scanning techniques to detect and stage neuroblastoma in children, using surgical and histopathologic correlation. We prospectively and retrospectively reviewed 16 MR examinations from 14 patients with neuroblastoma (13 patients) or ganglioneuroblastoma (1 patient) and compared these to computed tomography (CT) (5 patients) and pathology (all patients). Sequences included: precontrast T1-weighted and T2-weighted images, and gadolinium-enhanced T1-weighted images. The study time for each MR exam was also calculated. Five primary tumors were intrathoracic paraspinous masses, eight were adrenal, and 1 was presacral. Neural foraminal invasion was demonstrated on MR in four of 14 patients. Three of the four patients had undergone CT and neural foraminal invasion was shown in one. Vascular encasement was demonstrated in five of 14 patients on MR images. Three of the five patients had undergone CT and vascular involvement was shown in two. All cases of neural foramina invasion and vascular encasement were proven at surgery. There were no false positive or false negative MR studies of neural foraminal invasion or vascular encasement. Bone marrow invasion was shown in two of 14 patients on MR images which were confirmed by bone marrow aspirate. No false negative cases of bone marrow invasion was shown. In one patient, CT considered one neuroblastoma to be adrenal in location which was correctly shown to be intrathoracic on MR. The mean study time for MR imaging was 49 min. Current MR techniques are accurate at detecting and staging neuroblastoma, and coverage of chest, abdomen, and pelvis can be performed in less than one hour.

ADULT INTUSSUSCEPTION: DEMONSTRATION BY CURRENT MR TECHNIQUES

We describe magnetic resonance findings in three patients with small bowel intussusception from different etiologies including idiopathic, adenomatous polyps, and hamartomatous polyps. Magnetic resonance findings showed a bowel-within-bowel appearance in two patients and a coiled-spring appearance in one patient. These findings were best shown on T2-weighted images, and clear definition was present on breathing independent T2-weighted images using half fourier acquisition snap shot turbo spin echo T2-weighted images.

Extrahepatic abdominal imaging in patients with malignancy: Comparison of MR imaging and helical CT in 164 patients

The purpose of this study was to compare the performance of magnetic resonance (MR) imaging using currently available techniques with contrast‐enhanced single‐phase helical computed tomography (CT) in depicting extrahepatic disease in patients with malignancy. At two institutions, 164 patients with known or suspected malignancy underwent abdominal imaging with contrast‐enhanced helical CT and MR imaging. The prospective interpretations of the CT scans and MR examinations were used to assess the sensitivity of each imaging test in detecting benign and malignant extrahepatic disease at 17 anatomic sites. Imaging findings were compared with results of surgery in 57 patients and with the combined results of image‐guided biopsy, follow‐up cross‐sectional imaging studies, other concurrent imaging tests, and clinical follow‐up. For the 164 patients, helical CT scans depicted 221 of 316 (70%) sites of proven extrahepatic tumor compared with 288 sites (91%) (P < 0.0001) for MR imaging. For the 57 patients who underwent exploratory laparotomy, helical CT scans depicted 101 of 154 (66%) findings of surgically confirmed extrahepatic tumor compared with MR imaging, which depicted 139 sites (90%) (P < 0.0001). Anatomic sites at which MR imaging showed a significantly greater detection of extrahepatic tumor included the peritoneum, bowel, and vascular and osseous structures. For depiction of benign extrahepatic disease, there was no significant difference between helical CT and MR imaging. MR imaging, using currently available T1‐weighted, RARE T2‐weighted, and gadolinium‐enhanced imaging, is effective in depicting extrahepatic disease in patients with malignancy. Compared with single‐phase helical CT scanning, MR imaging shows an advantage in depicting tumor involving the peritoneum, omentum, bowel, and osseous and vascular structures. J. Magn. Reson. Imaging 2000;12:269–277.

Chemotherapy-treated liver metastases mimicking hemangiomas on MR images.

AbstractBackground: To report the observation that chemotherapy-treated liver metastases may mimic the appearance of hemangiomas on T2-weighted and serial postgadolinium gradient-echo magnetic resonance (MR) images. Methods: T2-weighted and serial postgadolinium spoiled gradient-echo images were prospectively and retrospectively analyzed in six patients. All patients had been treated with chemotherapy for a duration of 2–12 months. Histopathologic evaluation of liver lesions was performed in three patients. Results: Twelve lesions that resembled hemangiomas were identified. Lesions were 0.8–5.5 cm in diameter. All were well defined, oval or lobulated, and demonstrated decreased signal intensity on T1-weighted images and increased signal intensity on T2-weighted images. On immediate postgadolinium images, all lesions demonstrated peripheral nodular enhancement, which coalesced on delayed imaging. Final histopathologic diagnoses were as follows: hepatic metastases from colon cancer (two patients), ovarian cancer (two patients), pancreatic islet cell tumor (one patient), and breast cancer (one patient). Conclusions: Metastases treated by chemotherapy may mimic the appearance of hemangiomas on a variety of commonly employed MR techniques. In patients undergoing MR imaging for the evaluation of liver metastases, a history of prior chemotherapy administration and duration should be sought to prevent inaccurate staging and inappropriate therapeutic decision making.

Angiosarcoma of the liver: MR imaging pre- and post-chemotherapy

Angiosarcoma of the liver is a rare tumor of mesenchymal origin. We report the MR appearance of angiosarcoma of the liver on T1-weighted, T2-weighted, and serial gadolinium enhanced spoiled gradient echo images pre- and post-intravenous chemotherapy. On pre-treatment images, angiosarcoma lesions were well defined, high signal with central regions of low signal on T2-weighted images, and showed peripheral nodular enhancement on serial post gadolinium images. Lesions resembled hemangiomas, however low signal central regions on T2-weighted images was a distinguishing feature. Post-treatment images acquired 11, 15, and 17 months after initiation of therapy, demonstrated decrease in diameter or resolution of angiosarcoma masses. Lesions increased in signal on T1 weighted images and decreased in signal on T2 weighted images approaching the signal intensity of liver. Treated liver lesions enhanced negligibly on gadolinium enhanced images.

Magnetic resonance imaging of the abdominal aorta and iliac vessels using combined 3-D gadolinium-enhanced MRA and gadolinium-enhanced fat-suppressed spoiled gradient echo sequences

This study evaluates a combined protocol consisting of breath hold immediate post gadolinium 3-D gradient echo MR angiography and blood pool phase gadolinium-enhanced breath hold 2-D fat-suppressed spoiled gradient echo (SGE) sequences in the examination of diseases of the abdominal aorta and iliac vessels. Thirty-two patients with suspected disease of the abdominal aorta, major aortic branches, or iliac vessels underwent MR angiographic study from January 1996 to January 1997. Examinations were performed on a 1.5 T MR imager using 2-D axial SGE, coronal 3-D fast imaging in steady state precession (3-D FISP) following bolus administration of 40 mL of gadolinium, and axial and coronal blood pool phase gadolinium-enhanced fat-suppressed SGE. Post-processed data, including 3-D reconstructions using maximum intensity projection (MIP), targeted MIP, and multiplanar reconstruction (MPR) were evaluated. MR findings in all patients were correlated as follows: surgery (13 patients), angiography (11 patients), contrast enhanced CT (3 patients), non-contrast enhanced CT (1 patient), color doppler US (2 patients), and previous MR study (2 patients). MR findings correlated closely with findings at surgery or other imaging studies in 31 of 32 patients. One patient had renal artery occlusion that was misinterpreted as mild stenosis. The following vascular diseases were present: aneurysm disease [10 patients: aortic aneurysm (8 patients), inflammatory aneurysm (2 patients)], thoracoabdominal aortic dissection (2 patients), arteriovenous fistula (1 patient), stenoses and/or occlusion of the abdominal aorta, major aortic branches and iliac vessels [12 patients: stenoses and/or occlusion of the abdominal aorta with stenoses of the iliac vessels (9 patients), renal artery stenosis (2 patients), occlusion of the abdominal aorta (1 patient)], and occluded artery to pancreatic transplant artery (1 patient). Five patients had normal studies. The 3-D FISP technique accurately defined the luminal contours of vessels, allowing precise depiction of vessel stenosis (i.e., renal artery stenosis or common iliac artery stenosis) and clear demonstration of relationship of aortic branch vessels (i.e., renal arteries) to underlying aortic pathology (i.e., aortic aneurysm or dissection). Blood pool phase gadolinium-enhanced fat-suppressed SGE images were useful in the evaluation of the external surface of vessel walls, and providing accurate measurement of aneurysm diameter and other associated vascular entities (i.e., inflammatory aneurysm, left-sided IVC). Targeted MIP or MPR reconstruction were important for assessing stenoses of medium sized vessels such as renal arteries and branches of the iliac arteries, and for identifying accessory arteries. The combination of immediate post gadolinium 3-D FISP and blood pool phase gadolinium-enhanced fat-suppressed SGE is useful in the evaluation of the abdominal aorta, major aortic branches and iliac vessels. Immediate post gadolinium 3-D FISP images provides diagnostically useful information regarding vessel luminal contour, while blood pool phase gadolinium-enhanced fat-suppressed SGE provides ancillary information on the vessel wall and surrounding tissue.

The spotted spleen : CT and clinical correlation in a tertiary care center

PURPOSE The goal of our study was to examine the prevalence of multiple hypodense splenic nodules and their associated diagnoses and to correlate CT appearance with clinical presentation and diagnosis. METHOD Records of all patients undergoing contrast-enhanced CT from July 1994 through September 1997 were reviewed. Charts and CT scans of patients with multiple (more than five) hypodense splenic nodules were then evaluated. RESULTS During the search period, there were 8,764 patients examined. Multiple hypodense splenic nodules were identified in 45 patients. Sixteen patients had malignant neoplasia as an etiology, with two patients having a benign tumor. Ten patients had an infectious etiology; nine patients had an inflammatory but noninfectious etiology; in eight patients, a diagnosis was not established; five of these patients were followed for > 18 months. CONCLUSION Multiple hypodense splenic nodules are uncommon. Lymphoma, infection, and sarcoid were the three most common disorders in the symptomatic patient, with infection strongly correlated with a compromised immune system. In the asymptomatic patient, nonlymphomatous metastatic disease, benign tumor, and sarcoid were most common. Although overlap exists between diagnostic groups, lymphoma tends to have larger, more variable nodules, whereas infection tends to occur with smaller, more uniform nodules. Sarcoid is intermediate in appearance.

Hepatic angiomyolipoma with minimal fat content: MR demonstration

Hepatic angiomyolipoma is a rare entity. In this report, we describe the unusual MR findings of an angiomyolipoma with minimal fat content with histopathology correlation. This tumor had signal intensity features on various MR sequences including intense heterogeneous enhancement on immediate postgadolinium spoiled gradient echo images that resembled the appearance of a well-differentiated primary hepatocellular carcinoma. Angiomyolipoma with minimal fat content should be considered in the differential diagnosis of tumors with early diffuse heterogeneous enhancement on contrast enhanced images.

MR findings of intestinal graft-versus-host disease

Graft-versus-host disease (GVHD) occurs as a complication of allogenic bone marrow transplantation (BMT). The disease is characterized by skin rash, jaundice, mucosal inflammation, and diarrhea. In this report, we describe magnetic resonance (MR) findings of intestinal GVHD, which is correlated with endoscopic biopsy. MR findings demonstrated generalized increased bowel wall thickness associated with substantial bowel wall enhancement with gadolinium chelate.