Masaaki Akahane

Dose-reduced CT with model-based iterative reconstruction in evaluations of hepatic steatosis: How low can we go?

PURPOSEnTo determine whether dose-reduced CT with model-based iterative image reconstruction (MBIR) is a useful tool with which to diagnose hepatic steatosis.nnnMATERIALS AND METHODSnThis prospective clinical study approved by our Institutional Review Board included 103 (67 men and 36 women; mean age, 64.3 years) patients who provided written informed consent to undergo unenhanced CT. Images of reference-dose CT (RDCT) with filtered back projection (R-FBP) and low- and ultralow-dose CT (dose-length product; 24 and 9% of that of RDCT) with MBIR (L-MBIR and UL-MBIR) were reconstructed. Mean CT numbers of liver (CT[L]) and spleen (CT[S]), and quotient (CT[L/S]) of CT[L] and CT[S] were calculated from selected regions of interest. Bias and limits of agreement (LOA) of CT[L] and CT[L/S] in L-MBIR and UL-MBIR (vs. R-FBP) were assessed using Bland-Altman analyses. Diagnostic methods for hepatic steatosis of CT[L]<48 Hounsfield units (HU) and CT[L/S]<1.1 were applied to L-MBIR and UL-MBIR using R-FBP as the reference standard.nnnRESULTSnBias was larger for CT[L] in UL-MBIR than in L-MBIR (-3.18HU vs. -1.73HU). The LOA of CT[L/S] was larger for UL-MBIR than for L-MBIR (±0.425 vs. ±0.245) and outliers were identified in CT[L/S] of UL-MBIR. Accuracy (0.92-0.95) and the area under the receiver operating characteristics curve (0.976-0.992) were high for each method, but some were slightly lower in UL-MBIR than L-MBIR.nnnCONCLUSIONnDose-reduced CT reconstructed with MBIR is applicable to diagnose hepatic steatosis, however, a low dose of radiation might be preferable.

Lateral–Medial Dissociation in Orbitofrontal Cortex–Hypothalamus Connectivity

The orbitofrontal cortex (OFC) is involved in cognitive functions, and is also closely related to autonomic functions. The OFC is densely connected with the hypothalamus, a heterogeneous structure controlling autonomic functions that can be divided into two major parts: the lateral and the medial. Resting-state functional connectivity has allowed us to parcellate the cerebral cortex into putative functional areas based on the changes in the spatial pattern of connectivity in the cerebral cortex when a seed point is moved from one voxel to another. In the present high spatial-resolution fMRI study, we investigate the connectivity-based organization of the OFC with reference to the hypothalamus. The OFC was parcellated using resting-state functional connectivity in an individual subject approach, and then the functional connectivity was examined between the parcellated areas in the OFC and the lateral/medial hypothalamus. We found a functional double dissociation in the OFC: the lateral OFC (the lateral orbital gyrus) was more likely connected with the lateral hypothalamus, whereas the medial OFC (the medial orbital and rectal gyri) was more likely connected with the medial hypothalamus. These results demonstrate the fundamental heterogeneity of the OFC, and suggest a potential neural basis of the OFC–hypothalamic functional interaction.

Biliary architecture of livers exhibiting right-sided ligamentum teres: an indication for preoperative cholangiography prior to major hepatectomy

Objective To obtain information about the basic biliary anatomy of livers with right-sided ligamentum teres (RSLT). Summary of background data RSLT is a relatively rare anomaly with a reported incidence of 0.2–1.2%. Although the portal/hepatic venous and arterial anatomy of livers with RSLT has already been established, the biliary architecture of such livers remains unclear. Methods RSLT was detected in 48 patients during 12,071 consecutive image readings (0.4%). Of these patients, the cholangiograms of 46 patients were analyzed, and their intrahepatic biliary tree confluence patterns were classified. Results The following four unique biliary confluence patterns were identified in livers with RSLT: the symmetrical type (23/46), independent right lateral type (13/46), total left type (6/46), and total right type (1/46). Analyses of the portal and arterial branching patterns of these livers showed that there were no correlations between their biliary confluence patterns and their portal or arterial ramification patterns. Conclusion The basic biliary architecture of livers with RSLT was clarified. As the RSLT patients anomalous biliary confluences differed from those seen in normal livers and were difficult to predict, preoperative cholangiography should be performed prior to complex hepatobiliary surgery involving livers with RSLT to ensure patient safety.

A case of β-catenin-positive hepatocellular adenoma with MR imaging sign of diffuse intratumoral fat deposition

Hepatocellular adenoma (HCA) is a rare primary benign tumor of the liver, which occurs predominantly in young and middle-aged women. Recently, the subclassification of HCA was proposed by the Bordeaux group. Subsequently, characteristic radiological and clinical features have been revealed in each HCA subtype. According to the previous literature, diffuse intratumoral fat deposition is a very common finding in hepatocyte nuclear factor 1α-negative HCA, but this finding has been reported in β-catenin-positive HCA in the literature for only one case. In this case report, we report the second case of β-catenin-positive HCA with MR imaging sign of diffuse intratumoral fat deposition, confirmed immunohistologically on the basis of a surgical specimen. In addition, our case showed hypovascularity and isointensity on the hepatobiliary phase which have been reported as characteristic findings in β-catenin-positive HCA. Diffuse intratumoral fat deposition can be observed in β-catenin-positive HCA, which has a greater probability of malignant transformation than other types of HCA.

Relatedness-dependent rapid development of brain activity in anterior temporal cortex during pair-association retrieval

Functional MRI studies have revealed that the brain activity in the anterior temporal cortex during memory retrieval increases over months after memory encoding. Behavioral evidence has demonstrated that long-term memory can sometimes be consolidated more rapidly in one or two days. In the present functional MRI study, we manipulated the relatedness between paired faces to be retrieved in a pair-association task. The brain activity in the anterior temporal cortex during retrieval of paired associates increased rapidly in one day, as shown in previous studies. We found that the speed of the brain activity development was dependent on the level of semantic relatedness of paired faces. The results suggest that the semantic relatedness enhances the speed of formation of memory representation in the anterior temporal cortex.

Model-based iterative reconstruction and adaptive statistical iterative reconstruction: dose-reduced CT for detecting pancreatic calcification:

Background Iterative reconstruction methods have attracted attention for reducing radiation doses in computed tomography (CT). Purpose To investigate the detectability of pancreatic calcification using dose-reduced CT reconstructed with model-based iterative construction (MBIR) and adaptive statistical iterative reconstruction (ASIR). Material and Methods This prospective study approved by Institutional Review Board included 85 patients (57 men, 28 women; mean age, 69.9 years; mean body weight, 61.2u2009kg). Unenhanced CT was performed three times with different radiation doses (reference-dose CT [RDCT], low-dose CT [LDCT], ultralow-dose CT [ULDCT]). From RDCT, LDCT, and ULDCT, images were reconstructed with filtered-back projection (R-FBP, used for establishing reference standard), ASIR (L-ASIR), and MBIR and ASIR (UL-MBIR and UL-ASIR), respectively. A lesion (pancreatic calcification) detection test was performed by two blinded radiologists with a five-point certainty level scale. Results Dose-length products of RDCT, LDCT, and ULDCT were 410, 97, and 36 mGy-cm, respectively. Nine patients had pancreatic calcification. The sensitivity for detecting pancreatic calcification with UL-MBIR was high (0.67–0.89) compared to L-ASIR or UL-ASIR (0.11–0.44), and a significant difference was seen between UL-MBIR and UL-ASIR for one reader (Pu2009=u20090.014). The area under the receiver-operating characteristic curve for UL-MBIR (0.818–0.860) was comparable to that for L-ASIR (0.696–0.844). The specificity was lower with UL-MBIR (0.79–0.92) than with L-ASIR or UL-ASIR (0.96–0.99), and a significant difference was seen for one reader (Pu2009<u20090.01). Conclusion In UL-MBIR, pancreatic calcification can be detected with high sensitivity, however, we should pay attention to the slightly lower specificity.

Comparison of new and conventional versions of model-based iterative reconstruction in reduced-dose computed tomography for diagnosis of hepatic steatosis

PurposeTo compare new and conventional versions of model-based iterative reconstruction (MBIR) in reduced-dose computed tomography (CT) in terms of diagnostic performance for hepatic steatosis.Materials and methodsImages were reconstructed from standard-dose and aggressively reduced-dose (the dose-length product was reduced by 91xa0%) unenhanced abdominopelvic CT scans of 86 patients using filtered back projection (SD-FBP) and new and conventional versions of MBIR (RD-MBIRn and RD-MBIRc), respectively. The mean CT attenuation of the liver (CT[L]) and the spleen as well as the ratio of these parameters (CT[L/S]) were calculated. CT[L] <48 Hounsfield units (HU) and CT[L/S] <1.1 were applied to SD-FBP (used as the reference standard; the number of positive patients was 12 and 14, respectively), RD-MBIRn, and RD-MBIRc.ResultsCT[L]s in SD-FBP/RD-MBIRn/RD-MBIRc were 56.9/55.9/52.8xa0HU. The difference in CT[L] between RD-MBIRn and SD-FBP was within ±5.0xa0HU in most cases. The sensitivity/specificity/accuracy of CT[L] <48xa0HU in RD-MBIRn and RD-MBIRc were 1.00/0.97/0.98 and 1.00/0.92/0.93, respectively, showing that RD-MBIRn permits significant improvements in specificity and accuracy (Pxa0<xa00.05, McNemar test). For CT[L/S] <1.1, these values were 0.79/0.97/0.94 and 0.79/0.97/0.94 in RD-MBIRn and RD-MBIRc, respectively.ConclusionWhen CT[L] <48xa0HU was applied, RD-MBIRn presented a significantly improved hepatic steatosis diagnostic performance compared with RD-MBIRc; indeed, it was almost equivalent to that afforded by SD-FBP.

Data for behavioral results and brain regions showing a time effect during pair-association retrieval

The current data article provides behavioral and neuroimaging data for the research article Relatedness-dependent rapid development of brain activity in anterior temporal cortex during pair-association retrieval” (Jimura et al., 2016) [1]. Behavioral performance is provided in a table. Fig. 2 of the article is based on this table. Brain regions showing time effect are provided in a table. A statistical activation map for the time effect is shown in Fig. 3C of the article.

Portal encasement: Significant CT findings to diagnose local recurrence after pancreaticoduodenectomy for pancreatic cancer

BACKGROUND/OBJECTIVESnTo demonstrate the utility of portal encasement as a criterion for early diagnosis of local recurrence (LR) after pancreaticoduodenectomy (PD) for pancreatic ductal adenocarcinoma (PDAC).nnnMETHODSnA total of 61 patients who underwent PD for PDAC were included in this retrospective study. Portal stenosis was evaluated by sequential postoperative computed tomography (CT) scans and correlated with disease recurrence. In addition to the conventional LR diagnostic criterion of a growing soft tissue mass, LR was evaluated using portal encasement as an additional diagnostic criterion. Portal encasement was defined as progressive stenosis of the portal system accompanied by a soft tissue mass, notwithstanding the enlargement of the mass.nnnRESULTSnBenign portal stenosis was found on the first postoperative CT imaging in 16 patients. However, stenosis resolved a median of 81 days later in all but one patient whose stenosis was due to portal reconstruction during PD. Portal encasement could be distinguished from benign portal stenosis based on the timing of emergence of the portal stenosis. Portal encasement developed in 13 of the 19 patients with LR, including 6 patients in whom the finding of portal encasement led to the diagnosis of LR a median of 147 days earlier with our diagnostic criterion compared with the conventional diagnostic criteria.nnnCONCLUSIONSnPortal encasement should be considered as a promising diagnostic criterion for earlier diagnosis of LR after PD for PDAC.

Pulmonary Metastasis of Undifferentiated Uterine Sarcoma Forming Fluid-Containing Cyst:

Undifferentiated uterine sarcoma (UUS) is a high-grade sarcoma with no specific differentiation; however, it exhibits variable positivity for CD10 as an immunohistochemical marker of endometrial stroma, suggesting immunohistochemical differentiation into endometrial stroma. It has been reported that some low-grade endometrial stromal sarcoma pulmonary metastatic foci show cystic changes; however, whether pulmonary metastatic UUS foci are solid or cystic remains undescribed. A 63-year-old woman underwent a hysterectomy. The subsequent pathologic diagnosis was UUS. After the operation, she was treated with chemotherapy; however, pulmonary solitary shadow was radiologically detected. Eight months after the gynecologic operation, her pulmonary lesion was surgically resected. Pathologically, the lesion consisted of a cyst containing serous fluid with thick whitish wall composed of tumor cells, which led to the diagnosis of metastatsis of UUS. The cyst seemed to be formed via secondary degeneration. She remains healthy without recurrence 28 months after her first visit to our hospital.