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Wataru Gonoi,
Hiroyuki Akai,
Kazuchika Hagiwara,
Masaaki Akahane,
Naoto Hayashi,
Eriko Maeda,
Takeharu Yoshikawa, Shigeru Kiryu,
Minoru Tada,
Kansei Uno,
Naoki Okura,
Kazuhiko Koike,
Kuni Ohtomo
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ABSTRACT: BACKGROUND: Only one case of santorinicele without pancreas divisum pathophysiology (SWOPP) was previously reported. The purpose of the study was to determine the gross prevalence of SWOPP and santorinicele with pancreas divisum (SWPD) in community and patient populations, and investigate their clinical and radiographic features. METHODS: This cross-sectional study was performed at a tertiary referral centre. The Patient group comprised 2035 consecutive patients enrolled in the study who underwent magnetic resonance cholangiopancreatography (MRCP) studies. The Community group comprised 2905 consecutive subjects who participated in our whole-body medical check-up program that routinely includes MRCP studies. SWOPP was diagnosed when a saccular dilatation of the terminal portion of the dorsal pancreatic duct was observed unaccompanied by pancreas divisum or dominant dorsal duct. The prevalence of SWOPP and SWPD, and the clinical and radiological features were assessed in each group. RESULTS: Five cases of SWOPP were found in the Patient group (age range, 67--85 years; mean age, 73.6 years) (5/2035 = 0.25%; 95% confidence interval, 0.07--0.57); there were no cases of SWOPP in the Community group (0/2905 = 0.00%; 95% confidence interval, 0.00--0.10) (P = 0.01). Previous history of pancreatitis (4/5) and chronic pancreatitis (3/5) was more common in patients with SWOPP than in other subjects in the Patient or Community groups (both P < 0.05). Two cases of SWOPP were accompanied by reverse-Z type meandering main pancreatic duct. Six cases of SWPD were found. These cases were asymptomatic in 4/6, had a larger santorinicele (6.9 mm) than SWOPP patients (4.5 mm; P = 0.02), and were not associated with pancreatitis (0/6). CONCLUSIONS: The second to sixth reported cases of SWOPP were presented. SWOPP is a relatively rare condition found mostly in patients suffering pancreatitis, especially chronic pancreatitis, and may be an acquired condition. Santorinicele is not always accompanied by pancreas divisum.
BMC Gastroenterology 04/2013; 13(1):62. · 2.42 Impact Factor
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ABSTRACT: OBJECTIVE: To investigate the effect of saline flush on coronary CT angiography of proximal, middle, and distal coronary artery segments, using 320-row CT, and to compare two injection duration protocols as to amount of contrast in the right heart chambers. METHODS: This retrospective study was approved by the local ethics committee, and the requirement for informed consent to participate in this study was waived. The final study group included 108 patients who underwent coronary CT angiography. The first 36 patients received contrast medium without saline flush (group 1); the next 36 patients received contrast medium for 14s and saline flush (group 2); the last 36 patients received contrast medium for 12s and saline flush (group 3). The CT number, noise, contrast-to-noise ratio (CNR), and number of segments with a CT number greater than 325 Hounsfield units (HU) were recorded for proximal, middle, and distal segments. RESULTS: The CT numbers and the CNR in groups 2 and 3 were significantly higher than that in group 1 (p<0.005); the difference between groups 2 and 3 was not significant. The proportion of segments greater than 325HU improved with saline flush (p<0.05), with a larger improvement in the distal segments. CONCLUSIONS: Saline flush improves enhancement and CNR of coronary arteries, particularly of distal segments, in coronary CT angiography using 320-row CT. An average contrast medium injection of 44mL was feasible using a saline flush.
European journal of radiology 04/2013; · 2.65 Impact Factor
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ABSTRACT: OBJECTIVE: To investigate whether computed tomography (CT) attenuation test for differential diagnosis of adrenal nodule is applicable in patients with hepatocellular carcinoma (HCC) which shows similar image characteristics to adrenal adenoma. MATERIALS AND METHODS: This retrospective study was approved by our institutional review board, and the requirement for informed consent from study patients was waived. Searching picture archiving and communication system, we identified 3678 patients with HCC who underwent upper abdominal unenhanced CT scans between April 2002 and March 2010, and 114 adrenal nodules (39 adenomas and 75 metastases) were included for analysis. Ten nodules were confirmed pathologically while 104 had imaging diagnosis (enlarged or emerged during the study period). Size, CT number, and the internal characteristics of the lesions were recorded. RESULTS: Mean CT numbers of adrenal adenomas were significantly lower than those of metastases (P<0.0001, t-test) on unenhanced CT. Thresholds of 17 and 33 Hounsfield units (HU) provided the following sensitivity, specificity, and accuracy: 46.2%, 100%, and 81.6% at 17HU, and 94.9%, 89.3%, and 91.2% at 33HU, respectively. The area under receiver operating characteristic curve for the CT number test was 0.96. Metastases were significantly larger than adrenal adenoma (P=0.009, t-test). However, the accuracy of testing using mass size was 64.0% at most. All adenomas and metastases were depicted as homogeneous masses with the exception of two metastases that presented as heterogeneous masses (necrotic or lipomatous). CONCLUSION: Adrenal adenomas can be differentiated from HCC metastases using CT number on unenhanced CT.
European journal of radiology 03/2013; · 2.65 Impact Factor
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ABSTRACT: Our aim was to investigate when halfcycle reconstruction (HCR) was feasible in patients who were predicted to have a heart rate over 65 bpm in coronary CT angiography (CTA) using 320-row CT. Seventy-four patients who underwent multiple heart beat scanning were included. The time to reach 230 HU at the ascending aorta during the bolus tracking scan was recorded (T(230)). HCR image and multicycle reconstruction (MCR) image were reconstructed for each patient. Image quality for each coronary segment was rated on a 3-point scale (3: good, 1: poor). For each patient, we determined that a single beat acquisition was feasible for diagnosis (HCR group) when the number of segments graded score 1 in the HCR image was the same or less than that in the MCR image. Otherwise, we included the patients in the MCR group. HCR group and MCR group included 38 and 36 patients, respectively. Regression analysis showed that body height >1.66 m (odds ratio (OR), 5.74; CI 1.59-25.6; p < 0.007), T(230) >16 s (OR 3.11; CI 1.07-9.58; p = 0.04), and heart rate ≤72 bpm (OR 3.18; CI 1.11-9.49; p = 0.03) were related with the HCR group. When all three criteria were fulfilled, the calculated probability that MCR would improve image quality was only 7 %. When the heart rate is ≤72 bpm, single heart beat acquisition is feasible for patients with body height >1.66 m and T(230) > 16 s in coronary CTA using 320-row CT.
The international journal of cardiovascular imaging 11/2012; · 2.15 Impact Factor
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ABSTRACT: Several methods have been developed to reduce the radiation dose in coronary computed tomography angiography (CTA).
The objective of our study was to evaluate the effects of Adaptive Iterative Dose Reduction (AIDR) on objective and subjective image quality as well as the radiation dose, compared with conventional filtered back projection (FBP), in coronary CTA.
We retrospectively reviewed 100 consecutive patients who underwent coronary CTA. In the first 50 patients, a higher tube current was used, and images were reconstructed with FBP. In the last 50 patients, a lower tube current was used, and images were reconstructed with AIDR. Subjective and objective image quality (noise, signal-to-noise ratio, contrast-to-noise ratio) were assessed.
The median radiation dose of the AIDR group was 22% lower than that of the FBP group (4.2 vs 5.4 mSv; P = 0.0001). No significant difference was found in subjective image quality, noise, signal-to-noise ratio, or contrast-to-noise ratio between the 2 groups.
AIDR reduced the tube current which resulted in reduction of radiation dose in coronary CTA while maintaining subjective and objective image quality compared with coronary CTA reconstructed with FBP.
Journal of cardiovascular computed tomography 08/2012; 6(5):318-24.
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ABSTRACT: We compared diagnostic ability for detecting hepatic metastases between gadolinium ethoxy benzyl diethylenetriamine pentaacetic acid (Gd-EOB-DTPA)-enhanced magnetic resonance imaging (MRI) and diffusion-weighted imaging (DWI) on a 1.5-T system, and determined whether DWI is necessary in Gd-EOB-DTPA-enhanced MRI for diagnosing colorectal liver metastases.
We assessed 29 consecutive prospectively enrolled patients with suspected metachronous colorectal liver metastases; all patients underwent surgery and had preoperative Gd-EOB-DTPA-enhanced MRI. Overall detection rate, sensitivity for detecting metastases and benign lesions, positive predictive value, and diagnostic accuracy (Az value) were compared among three image sets [unenhanced MRI (DWI set), Gd-EOB-DTPA-enhanced MRI excluding DWI (EOB set), and combined set].
Gd-EOB-DTPA-enhanced MRI yielded better overall detection rate (77.8-79.0 %) and sensitivity (87.1-89.4 %) for detecting metastases than the DWI set (55.9 % and 64.7 %, respectively) for one observer (P < 0.001). No statistically significant difference was seen between the EOB and combined sets, although several metastases were newly detected on additional DWI.
Gd-EOB-DTPA-enhanced MRI yielded a better overall detection rate and higher sensitivity for detecting metastases compared with unenhanced MRI. Additional DWI may be able to reduce oversight of lesions in Gd-EOB-DTPA-enhanced 1.5-T MRI for detecting colorectal liver metastases.
Japanese journal of radiology 07/2012; 30(8):648-58. · 0.65 Impact Factor
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ABSTRACT: The purpose was to investigate the influence of shorter delay time on the interpatient variability in coronary enhancement and appropriateness of scan timing in coronary CT angiography (CTA) using bolus tracking method with 320-row CT. The bolus tracking scan was performed at the level of the bifurcation of the trachea for first 50 patients (group 1) and at the center level of the diagnostic scan for the last 50 patients (group 2). The CT number of the proximal coronary arteries was measured in the right coronary artery (RCA) and the left main trunk (LMT). The CT numbers of the right ventricle, left ventricle, ascending aorta, and descending aorta were also measured to consider the appropriateness of the scan timing. The delay time was longer in group 1 than in group 2 (7.0 vs. 2.6 s; p < 0.0001). The CT number within the RCA was 390 ± 75 HU for group 1 and 419 ± 42 HU for group 2. The CT number within the LMT was 396 ± 72 HU for group 1 and 420 ± 40 HU for group 2. The difference of average (p = 0.02 and 0.04) and standard deviation (p = 0.03 and 0.02) was statistically significant. The scan timing was early or late in 15 patients for group 1, but only 2 patients for group 2 (p = 0.0002). Shortening the delay time could reduce the interpatient variability in coronary enhancement with appropriate scan timing in coronary CTA.
The international journal of cardiovascular imaging 04/2012; · 2.15 Impact Factor
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ABSTRACT: Patients with hepatocellular carcinoma (HCC) complicated by portal vein tumor thrombus (PVTT) have an extremely poor prognosis. It is important to select adequate therapeutic options based on reliable prognostic factors using imaging studies and clinical data. Prognostic factors were analyzed in patients with HCC with PVTT in the first branch or main trunk of the portal vein. From 2000 to 2007, 107 consecutive patients with HCC with PVTT in the major portal vein were reviewed, and diagnostic images and clinical characteristics were retrospectively observed. Thirty-eight possible prognostic factors for survival were analyzed by the log-rank test and multivariate analysis using Cox's proportional hazards model. Median overall survival was 14 months following PVTT diagnosis. Survival rates at 6 months, 1, 2, and 3 years were 72.1%, 52.6%, 32.6%, and 29.6%, respectively. Independent prognostic factors for longer survival included:patient age < 65 years, Child-Pugh classification A/B, PVTT treatment, accumulation of Lipiodol in the PVTT after TACE, initial radical treatment for HCC, HCC located in a single lobe of the liver, and no invasion of HCC to the hepatic vein or bile duct. Survival was associated with liver function, tumor extension, and treatment for HCC and PVTT.
Acta medica Okayama 04/2012; 66(2):131-41. · 0.84 Impact Factor
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ABSTRACT: The purpose of this study was to evaluate the correlation between bolus-tracking parameters and heart rate (HR) with attenuation of the ascending aorta and create a linear regression model for predicting coronary attenuation in coronary computed tomography angiography (CCTA).
A total of 50 patients (31 men, 19 women; mean age, 67.2±10.8y) underwent CCTA using a 320-detector CT scanner. A bolus-tracking scan was performed to optimize the scan timing. The average HR under normal breathing for 10s was recorded just before the bolus-tracking scan started. Attenuation values of the pulmonary artery at 7s (PA(7)) and 10s (PA(10)) after the beginning of the injection were recorded during the bolus-tracking scan and the ascending aortic attenuation (CE(AAo)) was measured during the diagnostic scan.
A positive correlation was observed between PA(7) and CE(AAo) (r=0.41, P=0.003) and PA(10) and CE(AAo) (r=0.66, P<0.0001), and weak negative correlation was observed between HR and CE(AAo) (r=-0.46, P=0.15). A multivariable linear regression model for predicting CE(AAo) was evaluated, and the residual error between the predicted and the measured CE(AAo) was within approximately ±100HU.
Coronary attenuation could be predicted using HR and pulmonary artery attenuation during the bolus-tracking method.
European journal of radiology 02/2012; 81(11):3250-3. · 2.65 Impact Factor
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ABSTRACT: To investigate the natural outcome and clinical implication of hypointense lesions in the hepatobiliary phase of Gd-EOB-DTPA-enhanced MRI.
Forty patients underwent Gd-EOB-DTPA-enhanced MRI for preoperative evaluation of HCC. Hypointense lesions in the hepatobiliary phase that were hypovascular 5mm of more were extracted for follow-up. We performed a longitudinal study retrospectively for these lesions regardless of whether classical HCC developed or emerged in a different area from that of the lesions being followed.
Thirty one patients displayed 130 hypointense lesions on MRI and only nine showed no hypointense lesions. In total, 17 (13.1%) of 130 hypointense lesions on MRI developed into classical HCC. The cumulative rates for these lesions to develop into classical HCC were 3.2% at 1 year, 11.1% at 2 years and 15.9% at 3 years. The total occurrence rates of classical HCC (25.8% at 1 year, 52.6% at 2 years and 76.4% at 3 years) were higher compared to those regarding only occurrence of classical HCC from hypointense lesions on MRI (10.0% at 1 year, 35.6% at 2 years and 44.6% at 3 years), although no significant difference was observed (p=0.073).
Hypointense lesions that are detected in the hepatobiliary phase of Gd-EOB-DTPA-enhanced MRI have some malignant potential, although treating these lesions aggressively in patients who already have HCC may be too severe.
European journal of radiology 01/2012; 81(11):2973-7. · 2.65 Impact Factor
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Wataru Gonoi,
Hiroyuki Akai,
Kazuchika Hagiwara,
Masaaki Akahane,
Naoto Hayashi,
Eriko Maeda,
Takeharu Yoshikawa, Shigeru Kiryu,
Minoru Tada,
Kansei Uno,
Hiroshi Ohtsu,
Naoki Okura,
Kazuhiko Koike,
Kuni Ohtomo
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ABSTRACT: Meandering main pancreatic duct (MMPD), which comprises loop type and reverse-Z type main pancreatic duct (MPD), has long been discussed its relation to pancreatitis. However, no previous study has investigated its clinical significance. We aimed to determine the non-biased prevalence and the effect of MMPD on idiopathic pancreatitis using non-invasive magnetic resonance (MR) technique.
A cross-sectional study performed in a tertiary referral center. The study enrolled 504 subjects from the community and 30 patients with idiopathic pancreatitis (7 acute, 13 chronic, and 10 recurrent acute). All subjects underwent MR scanning and medical examination. MMPD was diagnosed when the MPD in the head of pancreas formed two or more extrema in the horizontal direction on coronal images of MR cholangiopancreatography, making a loop or a reverse-Z shaped hairpin curves and not accompanied by other pancreatic ductal anomaly. Statistical comparison was made among groups on the rate of MMPD including loop and reverse-Z subtypes, MR findings, and clinical features. The rate of MMPD was significantly higher for all idiopathic pancreatitis/idiopathic recurrent acute pancreatitis (RAP) (20%/40%; P<0.001/0.0001; odds ratio (OR), 11.1/29.0) than in the community (2.2%) but was not higher for acute/chronic pancreatitis (14%/8%; P = 0.154/0.266). Multiple logistic regression analysis revealed MMPD to be a significant factor that induces pancreatitis/RAP (P<0.0001/0.0001; OR, 4.01/26.2). Loop/reverse-Z subtypes were found more frequently in idiopathic RAP subgroup (20%/20%; P = 0.009/0.007; OR, 20.2/24.2) than in the community (1.2%/1.0%). The other clinical and radiographic features were shown not associated with the onset of pancreatitis.
MMPD is a common anatomical variant and might be a relevant factor to the onset of idiopathic RAP.
PLoS ONE 01/2012; 7(5):e37652. · 4.09 Impact Factor
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ABSTRACT: We investigated the characteristics and capability of interstitial MR lymphography in mice using gadofluorine 8, gadofluorine M, and gadofluorine P.
We injected healthy mice with 0.5 µmol of Gd gadofluorine 8, gadofluorine M, or gadofluorine P subcutaneously into the right rear footpad and assessed the time courses of contrast enhancement in the lymph nodes. Six mice were studied for each contrast agent. We also used gadofluorine M to assess the lymphatic pathway from the right and left rear feet or tail.
Contrast enhancement was demonstrated for the right popliteal, sacral, and iliac lymph nodes in all mice 5 minutes after injection of each of the 3 agents and decreased gradually. Enhancement in the lymph nodes was still detectable 30 minutes after injection of gadofluorine 8 or gadofluorine M. Enhancement became obscure sooner after gadofluorine P injection and was mildly stronger with the other 2 contrast agents. Clear differences were found in the hepatobiliary and urinary kinetics of the 3 agents. Gadofluorine M injected into various sites delineated the lymphatic pathway from the site of injection.
Interstitial MR lymphography using gadofluorine 8, gadofluorine M, and gadofluorine P offered clear visualization of the lymphatic pathway in healthy mice during a sufficient imaging time window, and allowed repeated assessment of the pathway and clarification of the lymphatic system.
Magnetic Resonance in Medical Sciences 01/2012; 11(2):99-107. · 0.97 Impact Factor
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ABSTRACT: To investigate the long-term time course of the contrast effects after the intravenous injection of gadofluorine M or gadofluorine P in mice.
Magnetic resonance images were acquired longitudinally after intravenous injection of 0.1 μmol Gd/g gadofluorine M into BALB/c mice. The contrast effects were also assessed in C57BL/6J mice injected with gadofluorine M, BALB/c mice injected with gadofluorine P, and BALB/c mice injected with a double dose of gadopentetate dimeglumine.
The injection of gadofluorine M into BALB/c mice caused prolonged contrast effects in the blood and other organs. The liver enhancement was especially long-lasting and still evident 6 days after injection. Strain-related differences in contrast kinetics of gadofluorine M were not observed between BALB/c mice and C57BL/6J mice. In comparison with gadofluorine M, clearances from the blood, liver, and kidney were more rapid and contrast enhancement in the spleen was generally lower for gadofluorine P. The enhancement in the gallbladder cavity, indicating biliary excretion, was evident only after gadofluorine P injection. Blood enhancement at 10 min was much weaker for gadopentetate dimeglumine.
Both gadofluorine M and gadofluorine P appear to be applicable to blood pool imaging and liver imaging in mice.
Japanese journal of radiology 12/2011; 30(1):86-91. · 0.65 Impact Factor
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ABSTRACT: To compare dual-energy computed tomography (CT) spectral imaging and conventional CT imaging in terms of precision of the measurement of CT numbers in phantoms.
A circular phantom (CP) and an elliptical phantom (EP) were used. Capsules filled with iodine contrast media solutions at various concentration levels were placed in the phantoms. Conventional CT was performed at a tube voltage of 120 kVp. Simulated monochromatic images at 65 keV were obtained by dual-energy CT spectral imaging. The CT number of each iodine capsule was measured. A linear regression model was used to evaluate linearity, while analysis of covariance was used to investigate the degree of variability according to phantom shape for each imaging method.
With conventional imaging, the slopes of the regression lines for CT numbers measured at the EP center and EP periphery were significantly lower than those measured for CP (P < 0.0001 for both EP center vs. CP and for EP periphery vs. CP). No significant difference in slope was found among phantom shapes in dual-energy spectral CT imaging.
Computed tomography numbers varied considerably depending on the phantom shape in conventional CT, whereas dual-energy CT provided consistent CT numbers regardless of the phantom shape.
Japanese journal of radiology 12/2011; 30(1):34-9. · 0.65 Impact Factor
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Journal of Behavioral and Brain Science 11/2011;
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Hiroyuki Akai, Shigeru Kiryu,
Izuru Matsuda,
Jirou Satou,
Hidemasa Takao,
Taku Tajima,
Yasushi Watanabe,
Hiroshi Imamura,
Norihiro Kokudo,
Masaaki Akahane,
Kuni Ohtomo
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ABSTRACT: To compare the diagnostic performance of Gd-EOB-DTPA-enhanced MRI with that of triple phase 64-MDCT in the detection of hepatocellular carcinoma (HCC).
Thirty-four patients with 52 surgically proven lesions underwent Gd-EOB-DTPA-enhanced MRI and triple phase 64-MDCT. Two observers independently evaluated MR and CT imaging on a lesion-by-lesion basis. Sensitivity, positive and negative predictive values and reproducibility were evaluated. The diagnostic accuracy of each modality was assessed with alternative-free response receiver operating characteristic (ROC) analysis.
Both observers showed higher sensitivity in detecting lesions with MRI compared to CT, however, only the difference between the two imaging techniques for observer 2 was significant (P=0.034). For lesions 1cm or smaller, MRI and CT showed equal sensitivity (both 62.5%) with one observer, and MRI proved superior to CT with the other observer (MRI 75% vs. CT 56.3%), but the latter difference was not significant (P=0.083). The difference in positive and negative predictive value between the two imaging techniques for each observer was not significant (P>0.05). The areas under the ROC curve for each observer were 0.843 and 0.861 for MRI vs. 0.800 and 0.833 for CT and the differences were not significant. Reproducibility was higher using MRI for both observers, but the result was not significant (MRI 32/33 vs. CT 29/33, P=0.083).
Gd-EOB-DTPA-enhanced MRI tended to show higher diagnostic accuracy, sensitivity and reproducibility compared to triple phase 64-MDCT in the detection of hepatocellular carcinoma, however statistical significance was not achieved.
European journal of radiology 11/2011; 80(2):310-5. · 2.65 Impact Factor
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ABSTRACT: We assessed lymph drainage in living mice by an integrated imaging method using fluorescence imaging (FLI) and magnetic resonance imaging (MRI). Mice were subcutaneously injected with quantum dots and gadofluorine 8 into the right rear footpad. They were fixed on a transparent flat plate and underwent FLI and MRI successively. Small markers were attached to the mouse surface for spatial coregistration, and image fusion of FLIs and MRIs was performed. Two-dimensional fluorescence reflectance imaging was used for FLI. FLI and MRI provided generally consistent results and demonstrated lymphatic flow to the popliteal, sacral, and iliac lymph nodes in most mice and to the renal, inguinal, and lumbar-aortic lymph nodes in some mice. On the fusion images, the locations of the lymph nodes in the mouse trunk were in good agreement between FLI and MRI, indicating successful spatial registration even for the deep structures. The popliteal node tended to be visualized a little farther caudally in FLI than in MRI, presumably because the overlying tissues were thicker in the cranial portion. Integrated FLI/MRI lymphography with image fusion appears to be a useful tool for analysis of the murine lymphatic system.
Molecular Imaging 10/2011; 10(5):317-26. · 3.18 Impact Factor
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ABSTRACT: To develop a method for body magnetic resonance imaging (MRI) of conscious mice and investigate the effect of isoflurane anesthesia and hypothermia on the hepatic kinetics of gadoxetate disodium (Gd-EOB-DTPA).
Conscious or anesthetized mice were restrained on a holder and the rectal temperature was measured serially. Serial MRI of the liver was performed after intravenous injection of Gd-EOB-DTPA with or without temperature control. Three mice were studied for each condition.
The temperature dropped rapidly in anesthetized mice beside the MR unit. The decline was less prominent in conscious mice. The temperature decreased less in anesthetized mice and remained constant in conscious mice in the radiofrequency (RF) coil. The washout of Gd-EOB-DTPA was slower in anesthetized hypothermic mice than in conscious normothermic mice. Warmed anesthetized mice showed faster washout, and cooled conscious mice showed delayed washout. Severer hypothermia in anesthetized mice resulted in weaker initial enhancement and slower washout.
By separately manipulating the presence or absence of anesthesia and hypothermia, we demonstrated that washout of Gd-EOB-DTPA was delayed under hypothermia, regardless of anesthesia. Serial body MRI of conscious mice was feasible and allowed the evaluation of kinetics of a contrast agent, while excluding the possible effects of anesthesia.
Journal of Magnetic Resonance Imaging 06/2011; 34(2):354-60. · 2.70 Impact Factor
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ABSTRACT: The aim of this study was to establish a distortion correction applicable to whole-body imaging of live mice.
All magnetic resonance imaging (MRI) scans were acquired on a compact 1-T permanent magnet unit for mouse imaging using a T1-weighted, three-dimensional (3D) fast low-angle shot sequence. We assessed geometric distortion in MR images of a small 3D grid phantom and determined 3D image transformations for distortion correction. The developed distortion correction was applied to MR images of the 3D grid phantom acquired on another day, and the correction was validated. A two-dimensional (2D) grid phantom was imaged with a mouse to investigate the applicability of the distortion correction to whole-body mouse imaging.
Obvious geometric distortion was observed in the MR images of the 3D grid phantom. The application of the developed 3D phantom-based distortion correction reduced distortion in the images of the 3D grid phantom acquired on another day. Geometric distortion was observed in the MR images of the 2D grid phantom acquired together with the mouse. The 3D phantom-based correction decreased the distortion substantially, regardless of mouse positioning.
The developed distortion correction can reduce distortion in whole-body imaging of live mice and may enhance the capabilities of MRI in small animal experiments.
Japanese journal of radiology 06/2011; 29(5):353-60. · 0.65 Impact Factor
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ABSTRACT: Gaussia luciferase (Gluc) is a secreted reporter, and its expression in living animals can be assessed by in vivo bioluminescence imaging (BLI) or blood assays. We characterized Gluc as an in vivo reporter in comparison with firefly luciferase (Fluc). Mice were inoculated subcutaneously with tumor cells expressing both Fluc and Gluc and underwent Fluc BLI, Gluc BLI, blood assays of Gluc activity, and caliper measurement. In Gluc BLI, the signal from the tumor peaked immediately and then decreased rapidly. In the longitudinal monitoring, all measures indicated an increase in tumor burden early after cell inoculation. However, the increase reached plateaus in Gluc BLI and Fluc BLI despite a continuous increase in the caliper measurement and Gluc blood assay. Significant correlations were found between the measures, and the correlation between the blood signal and caliper volume was especially high. Gluc allows tumor monitoring in mice and should be applicable to dual-reporter assessment in combination with Fluc. The Gluc blood assay appears to provide a reliable indicator of viable tumor burden, and the combination of a blood assay and in vivo BLI using Gluc should be promising for quantifying and localizing the tumors.
Molecular Imaging 04/2011; 10(5):377-85. · 3.18 Impact Factor
