Minoru Ishifuro

Electron Beam CT Versus 16-MDCT on the Variability of Repeated Coronary Artery Calcium Measurements in a Variable Heart Rate Phantom

OBJECTIVE High reproducibility of coronary artery calcium (CAC) scoring is a key requirement for monitoring the progression of coronary atherosclerosis. The purposes of this study were to compare electron beam CT and 16-MDCT scanners in the variability of repeated CAC measurements and to assess the factors influencing this variability. MATERIALS AND METHODS CAC models of different sizes attached to a cardiac phantom with a programmable variable heart rate were scanned three times, and interscan variability of the CAC measurement was calculated each time. For helical CT, different slice-thickness images of either retrospective ECG-gated or prospective ECG-triggering reconstruction were obtained. The detection of small amounts of calcium, variability of the Agatston score, and CAC measurement algorithms (Agatston, volume, and mass scores) were compared between CT scanners and protocols. RESULTS All 1-mm-sized calcium models were detected on 0.625- and 1.25-mm helical CT, whereas some were missed on electron beam CT and 2.5-mm helical CT. Retrospective ECG-gated thin-slice helical CT showed the lowest variability. Reduction of variability by volume and mass scoring algorithms was less effective on 0.625- and 1.25-mm-thickness CT. CONCLUSION Retrospective ECG-gated thin-slice helical CT has the potential to be a useful tool for monitoring coronary atherosclerosis.

Use of multidetector row CT with volume renderings in right lobe living liver transplantation.

Abstract. Multidetector row CT is a feasible diagnostic tool in pre- and postoperative liver partial transplantation. We can assess vascular anatomy and liver parenchyma as well as volumetry, which provide useful information for both donor selection and surgical planning. Disorders of the vascular and biliary systems are carefully observed in recipients. In addition, we evaluate liver regeneration of both the donor and the recipient by serial volumetry. We present how multidetector row CT with state-of-the-art three-dimensional volume renderings may be used in right lobe liver transplantation.

Significant correlation between spleen volume and thrombocytopenia in liver transplant patients: A concept for predicting persistent thrombocytopenia

Interferon (IFN) therapy with or without ribavirin treatment is well established as a standard antiviral treatment for hepatitis C virus (HCV)–infected patients. However, susceptibility to thrombocytopenia is a major obstacle for initiating or continuing this therapy, particularly in liver transplant (LTx) recipients with HCV. Studies have reported that splenectomy performed concurrently with LTx is a feasible strategy for conditioning patients for anti‐HCV IFN therapy. However, the relationship between the severity of splenomegaly and alterations in the blood cytopenia in LTx recipients remains to be clarified. Here, we analyzed the relationship between spleen volume (SV) and thrombocytopenia in 45 patients who underwent LTx at Hiroshima University Hospital. The extent of pre‐LTx splenomegaly [the SV to body surface area (BSA) ratio in an individual] was inversely correlated with both the post‐LTx white blood cell count and platelet (PLT) count (P < 0.001). Furthermore, the PLT count of patients with thrombocytopenia (PLT count ≤ 5 × 104/mm3) increased significantly in the group without splenomegaly (SV/BSA value < 400) versus that in the group with splenomegaly (P = 0.005). Thus, if both splenomegaly and thrombocytopenia coexist (PLT count ≤ 5 × 104/mm3 and SV/BSA value ≥ 400), persistent thrombocytopenia is predictable after LTx. Liver Transpl 15:208–215, 2009.

Coronary artery calcium scoring on different 64-detector scanners using a low-tube voltage (80 kVp).

PURPOSE The aim of this study was to compare the calcium score and reproducibility of coronary artery calcium scores obtained on the four kinds of 64-detector computed tomography (CT) scanners using standard (120 kVp) and low tube voltage (80 kVp) scan techniques. MATERIALS AND METHODS We scanned 80 and 120 kVp on all scanners. We calculated Agatston, volume, and mass scores for coronary artery calcium scoring on each scanner and compared the coefficients of variation of the calcium scores to evaluate reproducibility of among CT scanners. RESULTS The averages of the total mean Agatston score, total mean volume score, and total mean mass score at 80 kVp/120 kVp were 798.9/683.8, and 627.2/567.3, and 157.1/156.7, respectively. The total mean mass score was almost constant irrespective of the tube voltage. The total mean coefficients of variation for the four CT scanners were lower at 80 than 120 kVp (4.1% vs. 10.2% [total mean Agatston score], 3.2% vs. 9.6% [total mean volume score], and 3.2% vs. 9.4% [total mean mass score]). CONCLUSION Use of the low tube voltage technique can reduce variations in the coronary artery calcium scores obtained on different CT scanners.

Remission of Splenic Volume in the Recipient During the Course of Adult-to-Adult Living Donor Liver Transplantation: Evaluation Using Multislice Computed Tomography and Semiautomatic Software

AIM The purpose of the study was to examine changes in splenic volume among recipients during the course of adult-to-adult living donor liver transplantation (LDLT) using multislice computed tomography (CT) scanning with a semiautomatic volumetry software. MATERIALS AND METHODS Forty-eight patients, including 33 males and a mean overall age of 54 +/- 8 years), underwent liver transplantation for the primary disease of liver cirrhosis with or without hepatocellular carcinoma (n = 31/17, respectively). The mean MELD score was 14 +/- 6. The liver graft mass compared with recipient weight was 74% +/- 28%. Splenic artery embolization was not performed. Dynamic CT scans splenic volume, and platelet counts (10(3)/cm(3)) were obtained pre, < or =50 day and > or =90 days postoperatively. RESULTS The total time to generate volumetry and image postprocessing per examination was <10 minutes. One-factor analysis of variance (ANOVA) revealed that the average splenic volume tended to be reduced from pre- to post-LDLT, although not significantly: pre-LDLT, 469 +/- 270 mL; < or =day 50, 369 +/- 212 mL; and > or =day 90, 378 +/- 210 mL (P = .066). One-factor ANOVA revealed that the average platelet count was significantly different in the 3 periods: pre-LDLT, 69 +/- 32 x 10(3)/cm(3); < or =day 50, 181 +/- 253 x 10(3)/cm(3); and > or =day 90, 126 +/- 64 x 10(3)/cm(3) (P < .01). The post hoc Scheffé test revealed the statistical significance of the platelet counts between pre-LDLT and < or =day 50 (P < .01). CONCLUSION Splenic volumetry with multislice CT and semiautomatic software, which is simple and not time consuming, was able to evaluate remission from hypersplenism during the course of LDLT.

Bone tunnel change develops within two weeks of double-bundle anterior cruciate ligament reconstruction using hamstring autograft: A comparison of different postoperative immobilization periods using computed tomography

BACKGROUND The purpose of this study was to evaluate bone tunnel changes following anterior cruciate ligament (ACL) reconstruction during the early postoperative period using computed tomography (CT), and to understand the impact of postoperative immobilization on these changes. METHODS Twenty patients who underwent double-bundle ACL reconstruction using hamstring tendon autografts were included. We subcategorized patients into two groups: patients who underwent isolated ACL reconstruction and had three days of knee immobilization (Group A, n=10); and patients with concomitant meniscus injuries who underwent ACL reconstruction and meniscus repair simultaneously (Group B, n=10) had their knees immobilized for two weeks after surgery. Bone tunnel enlargement was evaluated using CT imaging at one to three days, two weeks, one month, three months and six months after surgery. The cross-sectional area of the femoral and tibial tunnels was measured, and enlargement rate was calculated. The tunnel center location at two weeks after surgery was also evaluated. RESULTS The mean cross-sectional area adjacent to the joint space of the femoral and tibial tunnels significantly increased immediately after surgery, especially in the first month (P<0.01). However, after one to six months they were not increased (P>0.01). There was no significant difference in tunnel enlargement rate between group A and B. Tunnel center location changed even in the first two weeks. CONCLUSIONS Bone tunnel enlargement following double-bundle ACL reconstruction occurred at an earlier time point after surgery than anticipated. Postoperative immobilization could not prevent bone tunnel enlargement, but might prevent tunnel migration.

Three-dimensional CT Venography: A Diagnostic Modality for the Preoperative Assessment of Patients with Varicose Veins

OBJECTIVE We preoperatively assessed varicose veins by means of computed tomography (CT) with contrast injection in the veins of the lower extremity (CT venography). This paper reports the procedures, results and implications of CT venography from the surgical aspect. METHODS A total of 48 legs in 39 patients were examined. Contrast medium was diluted ten-fold and injected into the lower extremity veins, often using a dual route of injection. The images were reconstructed with the volume-rendering method. RESULTS CT venography clearly visualized the veins with a small amount of contrast medium and facilitated the identification of anatomy that was not suitable for passing the stripper. In addition, CT venography helped identify unusual types of varicose veins or uncommon sites of inflow of small saphenous veins. Such information was helpful for avoiding unexpected vascular injury or for minimizing skin incision. Dual-route injection was beneficial to minimize the blind zones. Doppler ultrasound could be more focused on hemodynamic assessment and determination of incision sites. CONCLUSIONS CT Venography is feasible in all cases of varicose veins. When performed in conjunction with ultrasonography, it appears to facilitate the safe and efficient treatment of various types of varicose veins.

Preoperative simulation of the running course of the abducens nerve in a large petroclival meningioma: a case report and literature review

One of the most important and useful pieces of information in the preoperative evaluation of a large petroclival meningioma is the running course of the abducens nerve. The abducens nerve is small and has a long intracranial course, making it prone to compression by the tumor at various anatomical points. In relatively large tumors, it is difficult to confirm the entire course of the abducens nerve, even by heavy T2-thin slice imaging. We report a case of successful preoperative estimation of the course of the abducens nerve that aided in its complete preservation during the resection of a large petroclival tumor.