Comparison of CT and 18F-FDG PET for Detecting Peritoneal Metastasis on the Preoperative Evaluation for Gastric Carcinoma

OBJECTIVE: The aim of our study was to compare the accuracy of CT and 18F-FDG PET for detecting peritoneal metastasis in patients with gastric carcinoma. MATERIALS AND METHODS: One-hundred-twelve patients who underwent a histologic confirmative exam or treatment (laparotomy, n = 107; diagnostic laparoscopy, n = 4; peritoneal washing cytology, n = 1) were retrospectively enrolled. All the patients underwent CT and 18F-FDG PET scanning for their preoperative evaluation. The sensitivities, specificities and accuracies of CT and 18F-FDG PET imaging for the detection of peritoneal metastasis were calculated and then compared using Fisher's exact probability test (p < 0.05), on the basis of the original preoperative reports. In addition, two board-certified radiologists and two board-certified nuclear medicine physicians independently reviewed the CT and PET scans, respectively. A receiver-operating characteristic curve analysis was performed to compare the diagnostic performance of CT and 18F-FDG PET imaging for detecting peritoneal metastasis. RESULTS: Based on the original preoperative reports, CT and 18F-FDG PET showed sensitivities of 76.5% and 35.3% (p = 0.037), specificities of 91.6% and 98.9% (p = 0.035), respectively, and equal accuracies of 89.3% (p = 1.0). The receptor operating characteristics curve analysis showed a significantly higher diagnostic performance for CT (Az = 0.878) than for PET (Az = 0.686) (p = 0.004). The interobserver agreement for detecting peritoneal metastasis was good (κ value = 0.684) for CT and moderate (κ value = 0.460) for PET. CONCLUSION: For the detection of peritoneal metastasis, CT was more sensitive and showed a higher diagnostic performance than PET, although CT had a relatively lower specificity than did PET.

Comparison of Unmonochromatized Synchrotron Radiation and Conventional X-rays in the Imaging of Mammographic Phantom and Human Breast Specimens: A Preliminary Result

A simple imaging setup based on the principle of coherence-based contrast X-ray imaging with unmonochromatized synchrotron radiation was used for studying mammographic phantom and human breast specimens. The use of unmonochromatized synchrotron radiation simplifies the instrumentation, decreases the cost and makes the procedure simpler and potentially more suitable for clinical applications. The imaging systems consisted of changeable silicon wafer attenuators, a tungsten slit system, a CdWO4 scintillator screen, a CCD (Charge Coupled Device) camera coupled to optical magnification lenses, and a personal computer. In preliminary studies, a spatial resolution test pattern and glass capillary filled with air bubbles were imaged to evaluate the resOolution characteristics and coherence-based contrast enhancement. Both the spatial resolution and image quality of the proposed system were compared with those of a conventional mammography system in order to establish the characteristic advantages of this approach. The images obtained with the proposed system showed a resolution of at least 25micrometer on the test pattern with much better contrast, while the images of the capillary filled with air bubbles revealed coherence-based edge enhancement. This result shows that the coherence-based contrast imaging system, which emphasizes the refraction effect from the edge of materials of different refractive indexes, is applicable to imaging studies in fundamental medicine and biology, although further research works will be required before it can be used for clinical applications.

Mn-DPDP Enhanced T1-weighted Magnetic Resonance Cholangiography: Usefulness in the Diagnosis and Roadmap for the Treatment of Intrahepatic Choledocholithiasis

PURPOSE: To assess the preliminary findings of Mn-enhanced T1-weighted MR cholangiography for the evaluation of intrahepatic choledocholithiasis. MATERIALS AND METHODS: Seven patients with recurrent pyogenic cholangitis underwent conventional heavily T2-weighted and manganese-enhanced T1-weighted MR cholangiography. For the former, the two reviewers focused on intrahepatic ductal dilatation, calculi, and stricture; and for the latter, ductal enhancement. RESULTS: In seven patients, 13 diseased segments were depicted and intrahepatic bile ductal dilatation was present in all 13 of these in all seven patients. Calculi were present in eight segments in six patients, and stricture in four segments in three patients. Of the 13 diseased segmental ducts, six were seen at manganese-enhanced imaging to be filled with contrast material, suggesting a functioning bile duct. CONCLUSION: Combined T2-weighted and mangafodipir trisodium-enhanced T1-weighted MR cholangiography provides both anatomic detail and functional detail of the biliary system. Combined MR cholangiography is useful for the evaluation of intrahepatic choledocholithiasis, demonstrating the stricture and function of the segmental ducts involved.

Hilar Branching Anatomy of Living Adult Liver Donors: Comparison of T2-MR Cholangiography and Contrast Enhanced T1-MR Cholangiography in Terms of Diagnostic Utility

PURPOSE: To compare T2-weighted MR cholangiography (T2-MRC) and contrast-enhanced T1-weighted MRC (enhanced T1-MRC) in the assessment of biliary anatomy in donor candidates for living related liver transplantation (LRLT). MATERIALS AND METHODS: Thirty-three potential donors underwent MR examination for preoperative evaluation. Using the single-shot half-Fourier RARE sequence, T2-weighted single-section and coronal images were obtained, and enhanced T1-MRC was performed, using 3D GRE sequences after the administration of mangafodifir trisodium. To assess the hilar ductal branching pattern and determine diagnostic confidence, two reviewers first evaluated the unpaired T2-MRC and enhanced T1-MRC images, and then paired T2-MRC and enhanced T1-MRC images together. In particular, in 12 cases in which direct cholangiographys were performed, the feasibility of single duct-to-duct anastomosis was assessed using the unpaired and the paired sets sequentially. RESULTS: The reviewers' confidence tended to be higher for enhanced T1-MRC than T2-MRC, but the difference was not statistically significant. For both reviewers, confidence was significantly higher for the paired set than for T2- or enhanced T1-MRC alone (p < .001). The types of biliary anatomy determined in the paired set matched the consensus reading in 33 (100%) and 30 cases(91%) assessed by reviewer 1 and 2, respectively. The separate interpretation of T2- and enhanced T1-MRC findings matched the consensus interpretation in 30 (91%) and 28 cases (85%), respectively, assessed by reviewer 1, and 26 (79%) and 28 cases (85%), respectively, assessed by reviewer 2. The possibility of single anastomosis was accurately predicted in 91.6% of cases in T2-MRC, and 100% at enhanced T1-MRC and the combined set. CONCLUSION: In the evaluation of the biliary anatomy of potential donors for LRLT, the combined use of T2-MRC and enhanced T1-MRC may improve diagnostic confidence and decrease the occurrence of a non diagnostic or equivocal interpretation at T2-MRC alone.

Are the Delay Images Necessary to Evaluate the Liver Metastatic Lesions on Mangafodipir Trisodium Enhanced Liver MRI?: Comparison with Hepatocellular Carcinomas

PURPOSE: To assess whether ring enhancements of liver metastases on Mn-DPDP enhanced, early MR images were well visualized on delayed images, as compared with those of hepatocellular carcinomas (HCC), and to investigate the detection accuracy and conspicuity of each tumor. MATERIALS AND METHODS: Twenty patients with liver metastases and 15 with HCC were studied by Mn-DPDP enhanced, T1-weighted MR images. Peripheral ring enhancement and conspicuity were investigated. Differences in detection accuracy and frequency of ring enhancement in liver metastases and HCC were assessed. RESULTS: In liver metastases (n=69), 44 cases (63.8%) without ring enhancement and 25 (36.2%) with were noted on early images. Sixteen cases (23.2%) without ring enhancement, 38 (55.1%) with ring enhancement similar to the early images, and 15 (21.7%) with prominent ring enhancement were noted on delayed images. In HCC (n=37), 36 cases (97.3%) without ring enhancement and 1 case (2.7%) with were noted on early images. There was no difference of detection accuracy in liver metastases or HCC between the 2 readings. Ring enhancement and conspicuity of each tumor were superior on delayed images. Ring enhancement in liver metastases was better seen on delayed images. CONCLUSION: Ring enhancement in liver metastases was well presented on Mn-DPDP enhanced, delayed MR images, which was useful to differentiate liver metastases from HCC.

A Simple Text Searching System for Radiology Reports Based on World Wide Web Technology

PURPOSE: The authors have developed a system that searches for radiologic reports, and we have evaluated the utility of this system for clinical application, research and medical education. MATERIALS AND METHODS: The system retrieves radiologic reports from the OCS (ordering communication system) server and stores them in a separate computer. A CGI (common gateway interface) program was written to search the database with variable keywords given by the user. The system satisfied the requirements of functionality, accessibility and security. RESULTS: Users could search for radiologic reports with variable keywords using the web browser, and the user could refine the results using combinations of these keywords. The system has been running successfully for 2 years, and radiologists have used this system for searching or collecting cases, keeping reports and gathering statistics. CONCLUSION: The simple text searching system has been developed in a short time period with only small costs and a bit of hard effort, and this system is practical for clinical use, research and medical education.

Quantitative Assessment on Properties of LASER and CCD-based Film Digitizer / 대한의료정보학회지

Picture archiving and communication systems (PACS) has widely been used in many hospitals. Film digitizer has been used in order to create digital image file from conventional plain radiographic films for PACS. In this study, we quantitatively assessed the characteristics of film digitizer for both laser and CCD camera-based type used in Severance hospital. We created three test films to measure the quality of digitized images. The test films were then digitized by both laser and CCD camera-based film digitizer. Finally, the image files were transferred to the PC in which spatial resolution, contrast, and uniformity were evaluated. We also measured digitization time to evaluate the speed of digitizer. Modulation transfer function (MTF) was measured to evaluate the spatial resolution. Contrast was evaluated by measuring of useful range of optical density (OD). Contrast uniformity was calculated by the percentage of difference between minimum and maximum pixel values on the digitized images. Spatial resolution of laser digitizer was ~~5.0cycles/mm, while that of CCD-based unit was ~~1.5cycles/mm of spatial resolution at 10% of MTF. Useful range of OD for CCD unit was ~~77%, while that for laser unit was 100%. Contrast uniformities of laser unit were better than those of CCD-based unit. Digitization time was ~~10sec/film using CCD unit, and ~~60sec/film using LASER unit at film size of 17x14 inches. Laser digitizer can provide relatively higher image quality, while CCD-based unit has the advantage of higher speed than laser unit.

Migration of Digital Medical Image Data Stored through Mini-PACS to Full-PACS / 대한의료정보학회지

The purpose of this study was to evaluate the migration of medical image data stored thorough mini-PACS to full-PACS at Yonsei University Medical Center (YUMC). The image data to be migrated were 2.7 TB stored through approximately 4,500 CD archives at Yongdong Severance hospital and 4.7 TB (2:1 compression) stored through 196 digital linear tape (DLT) archives at Severance hospital. Prior to carrying out the migration, principles, methods and expected practical affairs for the migration were discussed and planned to optimize the migration work by considering the cost and the effectiveness of migration work. Migration gateway workstations were set up and a migration software tool was developed. Real migration works were performed based on the results of several migration simulations. Severance hospital decided to migrate all stored image data. The CD image data of 2.7 TB were estimated total 2,250 hr (about 94 days) migration time, but the practical migration work was completed within 3 months by using maximum 5 workstations. The DLT data of 4.7 TB were estimated total 100 days migration time by applying 16 hr working time per day with single workstation, however, the practical migration work was taken 5 months. Meanwhile, 20% of the DLT image data were not able to migrate because the DLT were partially damaged due to frequent access. In conclusion, a migration plan should be carefully prepared by considering the individual hospital environments because the server system, archival media, the network, and the policy of data management may be unique.

Imaging Findings of Giant Liposarcoma of the Esophagus

A giant esophageal liposarcoma showing rapid growth over 7 months is presented in 56-year-old man. It originated from the pharyngo-esophageal junction with a short stalk, and extended downward to the distal esophagus. A barium swallow study showed a large, sausage-like intraluminal mass in the dilated esophagus. CT and MR imaging showed a heterogeneous mass with a fatty component in the esophagus. A total laryngopharyngo-esophagectomy was performed and the histological diagnosis was of a well-differentiated liposarcoma.

Ultrasound-Guided Fine-Needle Aspiration Biopsy in Nonpalpable Thyroid Nodules: Is It Useful in Infracentimetric Nodules?

The purpose of this study was to evaluate the usefulness of an ultrasound-guided fine-needle aspiration biopsy (US-FNAB) for the evaluation and treatment planning of nonpalpable thyroid lesions, including infracentimetric nodules. One hundred and twenty one patients underwent US-FNAB for 149 non-palpable solid nodules. Sixty-five patients underwent surgery, and 84 were followed up for at least 36 months. The results of the US-FNAB correlated with the pathological findings and clinical follow-up results. The nodules ranged from 0.3 to 2 cm in diameter, with a mean of 0.8cm. Among the 149 nodules, 115 were infracentimetric and 34 were centimetric or supracentimetric in size. Of the 149 thyroid nodules, US-FNAB was true positive in 43, true negative in 90, false positive in 7 and false negative in 1. In 8 cases, the lesion was inadequately sampled. The sensitivity, specificity, positive predictive value, negative predictive value and accuracy of the US-FNAB for the infracentimetric nodules were 96.9, 93.4, 86.1, 98.6 and 94.4%, and for the centimetric or supracentimetric nodules, were 100, 90.5, 85.7, 100 and 93.9%, respectively. There were no significant differences in the results between the infracentimetric and centimetric or supracentimetric nodules. In conclusion, an US-FNAB is a useful tool for determining the treatment plan of non-palpable solid thyroid nodules, even when less than 1 cm in diameter, and shows high sensitivity, specificity and accuracy.

MRI after Sequential Use of Gadolinium Chelate and Mangafodipir Trisodium for the Evaluation of Focal Liver Lesions: Study of Image Findings and Safety

PURPOSE: To assess the feasibility of sequentially administering Gd-DTPA and Mn-DPDP for the MR imaging of focal hepatic lesions, and to investigate whether the procedures involved led to any adverse effects. MATERIALS AND METHODS: Forty-two patients (M:F=25:17) with suspected hepatic lesions underwent T1-weighted MR imaging procedures before and after Gd-DTPA enhancement, and after sequential Mn-DPDP administration. Two investigators reviewed the findings in terms of the size, number, morphology, and enhancement patterns of the lesions. Any adverse actions resulting from the procedures were noted. RESULTS: Fifteen patients had hepatocellular carcinoma (HCC, n=35), 13 showed liver metastases (n=40), nine had hemangioma (n=13), two had cholangiocarcinoma (CC, n=2), two had a liver abscess (n=2), and one had focal nodular hyperplasia (FNH, n=2). All focal hepatic lesions were clearly visible, with no difference in conspicuity between T1-weighted images obtained after Gd-DTPA administration and those obtained after Gd- DTPA plus Mn-DPDP administration. After the latter procedure, 12 HCCs showed high or iso- signal intensity to liver parenchyma and 23 showed no contrast enhancement. Thirty-eight liver metastases showed no contrast enhancement, but in two cases ring enhancement was observeed. In both cases of FNH, homogeneous enhancement was noted. No hemangiomas, CCs or abscesses demonstrated contrast enhancement. The only adverse reaction was five instances of facial flushing. CONCLUSION: Hepatic MR imaging after sequential Gd-DTPA plus Mn-DPDP administration may be selectively useful in differentiating between hepatocellular and non-hepatocellular tumor. No technical difficulties or severe adverse reactions were encountered.

Incidentally Found Thyroid Nodules in Women with no Previous Thyroid Disease: Its Significance

PURPOSE: To determine the prevalence of thyroid nodules discovered incidentally at ultrasonography and to reassess their significance. MATERIALS AND METHODS: During a six-month period and using a high-frequency transducer, 1033 subjects with suspected breast disease underwent a prospective study of the thyroid. We determined the prevalence of thyroid nodules according to age, and the malignancy rate. RESULTS: Focal thyroid nodules were detected in 291 women (28.2%), their prevalence increasing with age (p<0.01). The nodules, totalling 337, were single in 260 cases (89.3%) and multiple in 31 (10.7%); 271 were less than 1 cm in diameter, 53 were 1-2 cm, and 13 were more than 2 cm [mean, 7.1(range, 2-34) mm]; 126 (37.4%) were pure cysts, 62 (18.4%) were mixed, and 149 (44.2%) were solid. Of the 149 solid nodules, 139 were hypoechoic. Eighty women (with 106 nodules) underwent fine-needle aspiration bipsy, and 35 (with 45 nodules) underwent surgery. It was discovered, finally, that 29 women (2.8%) had 35 malignancies, of which 33 were papillary carcinomas and two were carcinomas which had metastasized from a breast malignancy. Eleven women (37.9%) had extrathyroidal invasion and 6 (20.7%) had cervical lymph node metastasis despite incidentaloma. CONCLUSION: The prevalence of incidentally found thyroid nodules was 28.2%. Since the malignancy rate of these was relatively high, at 10.4%, the clinical significance of this finding should be reassessed.

Usefulness of MRCP in the Diagnosis of Common Bile Duct Dilatation caused by Non-stone or Non-tumorous Conditions

PURPOSE: To evaluate the usefulness of MRCP in the diagnosis of the variable causes of common bile duct(CBD) dilatation, except stone or tumor MATERIALS AND METHODS: Twenty-six patients(M:F=15:11, mean age; 62 years) with both MRCP and ERCP were included in this study. Dynamic MRCP(n=12) and contrast-enhanced MRI(n=10) of abdomen were also added. Dilatation of CBD, intrahepatic ducts and pancreatic duct was evaluated, including coexistence of intrahepatic ductal stone, pancreatic pseudocyst, and papillitis or papillary edema. The criteria of CBD dilatation was over than 7 mm(n=21, without cholecystectomy) or 10 mm(n=5, with cholecystectomy) in diameter on T2-weighted coronal image. RESULTS: The mean diameter of CBD was 12.7 mm without cholecystectomy(9-19 mm) and 13.0 mm with cholecystectomy(10-15 mm), respectively(p>0.05). Cholangitis(n=11, 42.3%), chronic pancreatitis(n=8, 30.8%), stenosis of distal CBD(n=6, 23.1%), periampullary diverticulum(n=3, 11.5%), stenosis of ampulla of Vater(n=2, 7.7%), dysfunction of sphincter of Oddi(n=2, 7.7%), acute focal pancreatitis in the pancreatic head(n=2, 7.7%), papillitis(n=1, 3.8%), pseudocyst in the pancreatic head(n=1, 3.8%), and ascaris in CBD(n=1, 3.8%) were noted. Pancreatic duct dilatation(n=10, 38.5%) and duodenal diverticulum(n=3, 11.5%) were also seen on MRCP. On dynamic MRCP(12 patients), distal CBD was visualized in 2 patients(16.7%), which was not shown on routine MRCP. Only 1 patient(10.0%) showed papillitis with slightly enhancing papilla on contrast-enhanced MRI(10 patients). CONCLUSION: MRCP was thought to be helpful in the evaluation of the causes of CBD dilatation, not caused by stone or tumor, especially in the cases of stenosis of distal CBD and chronic pancreatitis, dysfunction of sphincter of Oddi on dynamic MRCP, and cholangitis and pericholangitic abnormality on contrast-enhanced MRI

MR Findings of Acute Graft-versus-Host Disease Involving Gastrointestinal Tracts

PURPOSE: To evaluate the MR findings of gastrointestinal graft-versus-host disease (GVHD) after allogenic bone marrow transplantation. MATERIALS AND METHODS: Five patients (M:F=3:2, age range: 9-58 years) with suspected gastrointestinal GVHD underwent abdominal MRI, and the findings were evaluated. Because of acute myelocytic leukemia (n=4) or non-Hodgkin's lymphoma (n=1), all had undergone allogenic bone marrow transplantation 2-6 (mean, 3.5) weeks earlier. T2-weighted half-Fourier acquisition snapshot turbo spin-echo, T1-weighted spoiled gradientecho (SGE), and postcontrast T1-weighted SGE MR imaging, with and without fat-suppression, was performed. RESULTS: All five patients showed bowel wall thickening and marked contrast enhancement in the jejunum (n=5), ileum (n=4), duodenum (n=3), sigmoid colon (n=3), gastric antrum (n=2), and rectum (n=2). Bowel wall thickening showed a target appearance in the jejunum (n=2, 40.0%), ileum (n=1, 25.0%), sigmoid colon (n=1, 33.3%), and rectum (n=1, 50.0%), while the remaining cases showed diffuse wall thickening without layering. Small amount of ascites was noted in four patients (80%), and multiple small conglomerated retroperitoneal lymph nodes in three (60%). In all patients, a signal intensity of slightly enlarged liver due to iron overload secondary to multiple blood transfusions, gave rise to decreased signal intensity at both T1-and T2-weighted MR imaging. CONCLUSION: In patients with GVHD, the commonly noted MR findings were bowel wall thickening with contrast enhancement, ascites and retroperitoneal lymphadenopathy.

Experimental and Clinical Studies on the Intraarterial Injection of Holmium-166 Chitosan Complex in the Treatment of Hepatocellular Carcinoma

PURPOSE: The purposes of this study were to evaluate the biodistribution and effect of Ho-166 radionuclide by intra-arterial injection of the Ho-166 chitosan complex in dogs and to assess the clinical efficacy and side effects of this complex in the treatment of hepatocellular carcinoma (HCC). MATERIALS AND METHODS: In an experimental study, 20 mCi of Ho-166 chitosan complex was injected into the left hepatic artery of six adult dogs. The distribution of radioactivity in each organ was calculated using a gamma camera scan at regular intervals. A beta ray radioactivity count (cpm) of blood and urine was performed periodically, and hematologic and hepatic function were regularly assessed. At 4, 8 and 12 weeks after intra-arterial injection, bone marrow and liver were pathologically evaluated. Twenty-five patients with a single, nodular HCC mass 3 -9 cm in diameter were treated by intra-arterial injection of Ho-166 chitosan complex, and immediately after the procedure a gamma camera scan was obtained. A beta ray radioactivity count(cpm) of blood was performed periodically, hematologic and hepatic function were regularly evaluated, and CT scans and angiograms were obtained 3 months after the procedure. On the basis of the CT and angiographic findings, the treatment effects were classified as complete (CR), partial (PR) or non-response(NR). RESULTS: In the animal study, blood radioactivity peaked immediately after injection and then declined rapidly. Urinary excretion was 0.17%. The proportion of radioactivity in each organ per whole body was 25% in the left lobe of the liver, 7% in the right lobe, 3% in the lung, 1.4 -3% in the bladder, and 2% in bone. WBC and platelet counts declined maximally at 3 -4 weeks and recovered at 12 weeks. The cellularity of bone marrow was 25% at 4 weeks and 55% at 12 weeks, findings which correlated well with the observed hematologic changes. In the clinical study of 25 HCC patients, CR was achieved in 17 (68%) cases, PR in 5 (20%) and NR in 3 (12%). At gamma camera imaging immediately after treatment, tumor radioactivity was localized in 76% of cases. In six cases (24%) WBC and platelet counts decreased 50% or more compared with their pretreatment level. In 67 -75% of cases, SGOT and SGPT were, within 1 -3 days, 2 -3 times higher than their pre-treatment level, and recovered at post 4 weeks. CONCLUSION: Ho-166 chitosan complex administrated intra-arterially localized the target organ with minimal side effects, and we therefore suggest that it may be used in the treatment of nodular and hypervascular HCC. Further study of its dosimetry and possible hematologic side reactions is needed, however.

Standard Performance Measurements of GE AdvanceTM Positron Emission Tomography / 대한핵의학회잡지

PURPOSE: The purpose of this study was to establish optimal imaging acquisition conditions for the GE Advance(TM) PET imaging system by performing the acceptance tests designed by National Electrical Manufacturers Association (NEMA) protocol and General Electric Medical Systems (GEMS) test procedures. MATERIALS AND METHODS: Performance tests were carried out with 18FDG radioactivity source and phantoms by using a standard acquisition mode. Transaxial resolution and scatter fraction tests were performed with a line source and axial resolution with a point source, respectively. A cylindrical phantom made of polymethylmethacrylate (PMMA) was used to measure sensitivity, count rate losses and randoms, uniformity correction, and attenuation inserts were added to measure remaining tests. The test results were acquired in a diagnostic acquisition mode and analyzed mainly on high sensitivity mode. RESULTS: Transaxial resolution and axial resolution were measured as average of 4.65 mm and 3.98 mm at 0 cm, and 6.02 mm and 6.71 mm at 20 cm on high sensitivity mode, respectively. Average scatter fraction was 9.87%, and sensitivity was 225.8 kcps/micronCi/cc of trues. Activity at 50% deadtime was 4.6 Ci/cc, and the error of count rate correction at that activity was from 1.49% to 3.83%. Average nonuniformity for total slice was 8.37%. The accuracy of scatter correction was -0.95%. The accuracies of attenuation correction were 5.68% for air, 0.04% for water and -6.51% for polytetrafluoroethylene (PTFE). CONCLUSION: The results satisfied most acceptance criteria, indicating that the GE AdvanceTM PET system can be optimally used for clinical applications.

Hepatic Parenchymal Changes After Percutaneous Injection of Holmium-166 in Rabbit

PURPOSE: To evaluate changes in rabbit liver parenchyma on MR images following percutaneous Holmium-166 injection, and to correlate those changes with histologic findings. MATERIALS AND METHODS: Holmium-166 (10-25 mCi) was percutaneously injected into the liver of rabbit (n=12) under sonographic guidance. MR images were obtained between one to two weeks (acute phase) after the injection in four rabbits, and between two to four weeks (subacute phase) after the injection in four rabbits. Tissue specimens of these eight rabbits were obtained immediately after MR imaging. Tissue specimens were obtained without MR imaging in four rabbits (between one to two weeks in one rabbit and between three to four weeks in three rabbits). RESULTS: Tissue specimens showed central liquefactive necrosis and peripheral coagulative necrosis containing deposition of small particles and hemorrhage. The peripheral margin of the lesions showed formation of the granulation tissue with fibrosis, which tended to be more prominent in subacute phase. The area of the necrosis tended to correlate with the dose of the radioactive Holmium-166. On MR images, the central portion of the necrosis showed hyperintensity on T2-weighted image, hypointensity on the precontrast T1-weighted images, and no enhancement on the dynamic MR images. The peripheral portion of the necrosis showed hypointensity on T2-weighted images, iso or mild hypointensity on the T1-weighted images, and mild peripheral enhancement on the delayed dynamic MR images. The peripheral margin of the lesion showed hypointensity on both T1- and T1-weighted images with increased enhancement on the delayed phase images of the dynamic MR images. CONCLUSION: After percutaneous Holmium-166 injection into rabbit liver parenchyma, the central portion showed liquefactive necrosis, the peripheral portion showed coagulative necrosis with granulation, fibrosis, hemorrhage and depostition of small granules. MR imaging may be helpful in evaluation of the histological change of the liver after percutaneous Holmium-166 treatment.

Test-bolus injection for optimization of arterial phase imaging during contrast-enhanced hepatic MR imaging

Contrast enhancement during the dynamic MR imaging is important for the detection and characterization of focal liver lesions. The purpose of this study was to determine whether or not a timing examination with a injection of a 1.0-mL bolus of gadopentetate dimeglumine into the antecubital vein followed by rapid dynamic scanning and measurement of signal intensity of the aorta could help to obtain proper arterial-dominant phase images for the characterization of focal hepatic lesions during subsequent multiphase dynamic MR imaging. The imaging delay to acquisition of the first gadolinium-enhanced image for multiphase dynamic MR imaging was set to equal the time to peak aortic enhancement during the test examination. The first contrast-enhanced images of 80 patients with 160 focal liver lesions (hepatocellular carcinoma, n = 79; cavernous hemangioma, n = 51; metastatic tumor, n = 30) were then retrospectively reviewed. Peak aortic enhancement occurred between 10 and 28 seconds (mean, 16.5 seconds +/- 3.1) after starting the infusion of contrast material in 80 patients during the test-examination. Depending on the findings of intrahepatic vascular enhancement on the full-scale dynamic images, hepatic arterial phase (n = 11, 14%) or sinusoid phase (n = 65, 81%) imaging was obtained during the first gadolinium-enhanced acquisition in 76 (95%) of 80 patients. Three different lesions were well characterized and easily distinguished from each other (p < .0001) on the first-phase images depending on their enhancement pattern. In the majority of patients, timing examination with test-bolus injection was helpful in obtaining qualified images for the characterization of various focal lesions.

Radiologic findings of Mirizzi syndrome with emphasis on MRI

We have reported a case of Mirizzi syndrome preoperatively diagnosed using MR cholangiopancreatography. MRCP and T2-weighted image using a single-shot fast spin-echo sequence accurately depicted all components of Mirizzi syndrome, including impacted stone in the neck of the gallbladder compressing the common hepatic duct and wall-thickening of the gallbladder without any evidence of malignancy. The combination of MRCP and T2-weighted image can be counted on to replace conventional modalities of diagnosing Mirizzi syndrome without any loss of diagnostic accuracy.

Radiologic Findings of the Serous Cystadenomas of the Pancreas with Macro cystic or Unilocular Variants: Comparison with the Pathologic Findings

PURPOSE: To evaluate the radiologic findings of the serous cystadenomas of the pancreas with macrocystic or unilocular variants and to compare them with the pathologic findings. MATERIALS AND METHODS: In eight patients(7 females and 1 male ranging in age from 26 to 49 [mean, 37] years) with surgically proven serous cystadenomas, the findings of abdominal CT(n=8), abdominal sonography(US, n=8), endoscopic retrograde pancreatography(ERCP, n=6), endoscopic sonography(EUS, n=3), and MRI(n=1) were evaluated. The location and size of tumors, lobulation, internal septa, solid component, calcification, communication with the pancreatic duct, dilatation of the proximal pancreatic duct, and contrast enhancement on CT were assessed and compared with the pathologic findings. RESULTS: Tumors were located in the head(n=3), body(n=3) and tail(n=2), and their mean size was 4 (range, 1 -8) cm. Abdominal CT scanning revealed well-defined cystic masses composed of macrocyst(s) with calcifica-tion(n=3) and dilatation of the proximal duct (n=2). Three cases showed contrast enhancement of the cystic walls, the pathologic examination of which revealed fibrotic tissues. Four tumeurs were unilocular without septation or lobulation; these features, together with calcification, were depicted more clearly by US and EUS. ERCP revealed no communication between the cysts and pancreatic ducts. Imaging studies showed that macrocystic adenomas were superimposed on mucinous cystadenomas, and unilocular adenomas were indis-tinguishable from pseudocysts. CONCLUSION: Serous cystadenomas of the pancreas with macrocystic or unilocular variants are common in middle-aged women. Features present due to the existence of fibrotic tissues, and which may be reveled by contrast-enhanced CT, include internal septa, calcification, duct dilation, and prominent enhancement of the cystic wall. Serous cystadenoma should be included in the differential diagnosis of macrocystic or unilocular cystic lesions of the pancreas.