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Background: Septal penetration causes collimator-dependent differences in the heart-to-mediastinum (H/M) ratio in I-metaiodobenzylguanidine (MIBG) cardiac imaging. We investigated generally applicable methods to correct such differences. Methods and Results: Four hours after I-MIBG injection, 40 patients underwent anterior chest imaging successively with medium-energy (ME) and various non-ME collimators. The H/M ratios obtained with the non-ME collimators before and after I-dual-window penetration correction were compared with the ME-derived standard values to determine patient-based conversion equations for empiric and combined corrections, respectively. A I point source was imaged with various collimators, and the central ratio, the ratio of count in a small central region of interest to count in a large one, was calculated. The method of predicting the conversion equations from the central ratios was determined. Correction using the patient-based conversion equations removed systematic underestimation of the H/M ratios obtained with the non-ME collimators, and combined correction depressed residual random errors to some degree. Point-source-based equations yielded results comparable to the patient-based equations. Conclusions: Empiric and combined corrections effectively reduce collimator-dependent differences in the H/M ratio. The conversion equations can be predicted from simple point-source imaging, which would allow to apply these corrections to data obtained with various collimators. [ABSTRACT FROM AUTHOR]

We often observe patients with antiphospholipid syndrome (APS) presenting with both venous and arterial thrombi. Anticoagulant therapy is effective for venous and peripheral arterial embolisms in these patients; however, it has opposite effects when applied for thoracic aortic mural thrombosis because of the risk of new arterial embolisms. Recently, thoracic endovascular aortic repair (TEVAR) has been used to prevent arterial embolisms due to aortic thrombosis. However, we generally hesitate to implant artificial materials in patients in a hypercoagulable state because this can cause new thrombi to develop. Here, we present a case of successful treatment by anticoagulant therapy and TEVAR in an APS patient presenting with pulmonary embolisms (PEs) and multiple arterial embolisms due to thoracic aortic mural thrombosis. A 46-year-old man was referred to our hospital due to dyspnea and leg pain. Since contrast-enhanced computed tomography revealed PEs, thoracic aortic mural thrombosis, and lower limb arterial embolisms, we administered anticoagulation therapy. Three days later, contrast-enhanced computed tomography revealed new arterial embolisms in the right kidney. To prevent further arterial embolisms due to thoracic aortic mural thrombosis, we performed emergent TEVAR in addition to anticoagulant therapy. Thereafter, no venous or arterial embolisms recurred during the 13-month follow-up period. < Learning objective: An optimal therapy has not been established for patients in a hypercoagulable state who are threatened by venous thrombi and multiple arterial embolisms due to thoracic aortic mural thrombosis. In such patients, in addition to anticoagulant therapy, thoracic endovascular aortic repair for thoracic aortic mural thrombosis can be a promising option to prevent further arterial embolisms.> [ABSTRACT FROM AUTHOR]

Adult aortic coarctation is often asymptomatic and this condition can be detected because of a murmur or unexplained hypertension. Here, we report an adult case of aortic coarctaion with heart failure and a characteristic finding of pulsation below the bilateral clavicle.　 A 58-year-old man with refractory heart failure due to unknown reasons was referred to our hospital. Auscultation presented no murmur and high blood pressure had been treated with medicine. Interestingly, precise physical examination revealed the bilateral pulsation at the midclavicular line from the 2nd to the 5th intercostal areas. Echographic examination revealed the dilated vessel and arterial blood flow 1–2 cm in depth from the body surface at the midclavicular 2nd intercostal areas. Contrast-enhanced computed tomography showed thoracic aortic coarctation and a well-developed collateral circulation via the bilateral internal thoracic arteries and epigastric arteries. The cause of heart failure was diagnosed as aortic coarctation. Palliative revascularization was performed and his blood pressure was lowered. When we see the patients with refractory heart failure due to unknown reasons, pulsation below the bilateral clavicle may give us a clue to diagnose the “hidden” aortic coarctation. < Learning objective: We must consider adult aortic coarctation when we see patients with refractory heart failure. Although the present case did not show a cardiac murmur characteristic of aortic coarctation, we found out the very unique sign of pulsation below the bilateral clavicle. When we see patients with refractory heart failure due to unknown reasons, pulsation below the bilateral clavicle may give us an important clue to diagnose the “hidden” aortic coarctation.> [ABSTRACT FROM AUTHOR]

Purpose To evaluate the feasibility of transarterial therapy (transcatheter arterial chemoembolization and transcatheter arterial infusion) for patients with hepatocellular carcinoma and chronic kidney disease (CKD). Materials and Methods The study enrolled 35 patients who received transarterial therapy. The patients were classified into a CKD group (n = 10 nondialysis chronic kidney disease [NDCKD] and n = 9 end-stage renal disease [ESRD]) or a non-CKD group (n = 16). The survival rates between the two groups were compared using two different starting points: ( a ) from initial diagnosis of hepatocellular carcinoma and ( b ) from enrollment in the study. The tolerance of transarterial therapy in patients with CKD was evaluated by comparing the incidence of major adverse events. Results The 2-year and 5-year survival rates from initial diagnosis were 83.9% and 53.8% in the CKD group and 70.1% and 40.4% in the non-CKD group ( P = .478). The corresponding 3-year survival rate from enrollment in the two groups was 25.6% and 41.2%, respectively ( P = .995). The 2-year and 5-year survival rates from initial diagnosis were 70.1% and 40.4% in the non-CKD group, 90.0% and 39.4% in NDCKD patients, and 76.2% and 76.2% in ESRD patients ( P = .380). The corresponding 2-year survival rates from enrollment in these groups were 54.9%, 48.0%, and 48.6% ( P = .943). Severe contrast-induced nephropathy (n = 3) and late-onset death caused by cholesterol crystal embolism (n = 1) were observed in the NDCKD group. Conclusions Transcatheter arterial chemoembolization is feasible in patients with CKD by instituting periprocedural hemodialysis with similar 2-year and 5-year survival compared with patients without CKD. [ABSTRACT FROM AUTHOR]

Background: Septal penetration causes underestimation of the heart-to-mediastinum (H/M) ratio in cardiac I-metaiodobenzylguanidine (MIBG) imaging with a low-energy high-resolution (LEHR) collimator. We aimed to improve the method of estimating the H/M ratios using the LEHR collimator. Methods and Results: 4 hours after I-MIBG injection, 40 patients were imaged successively with the medium-energy (ME) and LEHR collimators using gamma cameras having 3/8-inch crystals. Severe underestimation of the H/M ratios was observed with the LEHR collimator when compared to the ME collimator. Narrowing the energy window width did not reduce the underestimation. Application of I-dual-window (IDW) correction using a narrow or wide subwindow reduced the underestimation substantially but not entirely. The H/M ratios estimated from the LEHR images with or without IDW correction were corrected based on their correlations with the ratios estimated from the ME images. This empiric correction removed systematic underestimation, and residual errors were reduced when the H/M ratios after IDW correction were converted using the empiric equation. The conversion equation was successfully applied to the correction of the H/M ratios determined in another 40 patients using a 5/8-inch crystal. Conclusions: In estimating the H/M ratios using an LEHR collimator, empiric correction combined with IDW correction improves concordance with ME-based values in comparison with empiric correction alone. [ABSTRACT FROM AUTHOR]

Abstract: Purpose: To prospectively compare the navigator-echo triggering technique (navigator technique) and the conventional respiratory triggering technique using bellows (bellows technique) for free-breathing three-dimensional (3D) magnetic resonance cholangiopancreatography (MRCP) under clinical conditions. Materials and methods: Forty patients referred for evaluation of biliary or pancreatic diseases underwent 3D MRCP examination using both navigator and bellows techniques. Two independent radiologists visually evaluated the image quality of 12 segments of the pancreaticobiliary tree in a blinded manner. In addition, the clarity of the lesion was compared between the two techniques in a side-by-side manner. Result: MRCP images were successfully acquired using both techniques in all patients. No significant difference in acquisition time was found between the two techniques. The image quality was significantly better using the navigator technique than using the bellows technique for the following seven segments: the head, body, and tail of the pancreatic duct; right hepatic duct; anterior and posterior segments of the right hepatic duct; and cystic duct. The other segments (common hepatic and bile duct, left hepatic duct, medial and lateral segments of left hepatic duct, gallbladder) showed no significant difference. The clarity of lesion depiction was significantly better using the navigator technique than using the bellows technique. Conclusion: Respiratory-triggered 3D MRCP using the navigator technique was shown to be feasible in routine clinical practice. The navigator technique improved the image quality of free-breathing 3D MRCP compared with the bellows technique. The clarity of lesion visualization was also better using the navigator technique than using the bellows technique. [Copyright &y& Elsevier]

Background: Septal penetration causes collimator-dependent differences in the heart-to-mediastinum (H/M) ratio in 123I-metaiodobenzylguanidine (MIBG) cardiac imaging. We investigated generally applicable methods to correct such differences.Methods and Results: Four hours after 123I-MIBG injection, 40 patients underwent anterior chest imaging successively with medium-energy (ME) and various non-ME collimators. The H/M ratios obtained with the non-ME collimators before and after 123I-dual-window penetration correction were compared with the ME-derived standard values to determine patient-based conversion equations for empiric and combined corrections, respectively. A 123I point source was imaged with various collimators, and the central ratio, the ratio of count in a small central region of interest to count in a large one, was calculated. The method of predicting the conversion equations from the central ratios was determined. Correction using the patient-based conversion equations removed systematic underestimation of the H/M ratios obtained with the non-ME collimators, and combined correction depressed residual random errors to some degree. Point-source-based equations yielded results comparable to the patient-based equations.Conclusions: Empiric and combined corrections effectively reduce collimator-dependent differences in the H/M ratio. The conversion equations can be predicted from simple point-source imaging, which would allow to apply these corrections to data obtained with various collimators. [ABSTRACT FROM AUTHOR]

Objectives: We investigated the clinical usefulness of respiratory navigator-gating technique for the assessment of liver tumors in Gd-EOB-DTPA-enhanced magnetic resonance (MR) imaging. Methods: Eighty patients who underwent Gd-EOB-DTPA-enhanced MR imaging to evaluate known or suspected liver tumors were enrolled. Three-dimensional spoiled gradient-recalled echo images of the liver were acquired in the hepatobiliary phase by the following three methods: breath-hold imaging, navigator-gated low-resolution imaging, and navigator-gated high-resolution imaging. Navigator-gated imaging was performed during free breathing. Spatial resolution was identical between breath-hold imaging and gated low-resolution imaging. Signal intensities in the liver, muscle, and spleen were measured in 20 patients. Image quality was visually evaluated in all 80 patients. The detection rate and lesion conspicuity were assessed for 71 malignant liver lesions identified in 29 patients. Results: The liver-to-muscle and liver-to-spleen signal ratios were significantly lower for gated images compared to breath-hold images. Images of acceptable quality were obtained in most patients by all three methods, and the overall image quality of axial images did not differ significantly among the imaging methods, although superior reformatted coronal images were obtained by gated high-resolution imaging. The detection rates of malignant liver lesions were similar among the three imaging methods, although lesion conspicuity was significantly better for breath-hold imaging compared to gated imaging. Conclusions: Navigator-gated imaging provided image qualities and detection rates of malignant liver lesions comparable to breath-hold imaging in Gd-EOB-DTPA-enhanced MR imaging; however, no additional benefits of high-resolution imaging were proven for lesion evaluation. [ABSTRACT FROM AUTHOR]

Compressed sensing-based reconstruction (CSR) is a new magnetic resonance (MR) image reconstruction method based on the compressed sensing (CS) technique. CSR suppresses ringing artifacts from truncated k-space sampling by estimating the high spatial frequency information required to support the acquired k-space data. CSR is intended to replace the existing zero-fill interpolation (ZIP) reconstruction. We investigated the usefulness of the CSR technique by obtaining sagittal T2-weighted images of the cervical spine and phantom images using CSR or ZIP. Our results indicated that the CSR technique reduces truncation artifacts compared to ZIP without prolonging the scan time or impairing image sharpness. • CSR technique allowed for reduction of truncation artifacts in cervical spine MR images. • CSR technique reduced striped artifacts without prolongation of the scan time. • CSR technique can reduce truncation artifacts while maintaining sharpness, in contrast to windowing with an apodizing filter. • The results of this preliminary study warrant further investigations of the utility of CSR in patients. [ABSTRACT FROM AUTHOR]

To optimize the navigator-gating technique for the acquisition of high-quality three-dimensional spoiled gradient-recalled echo (3D SPGR) images of the liver during free breathing. Materials and methods Ten healthy volunteers underwent 3D SPGR magnetic resonance imaging of the liver using a conventional navigator-gated 3D SPGR (cNAV-3D-SPGR) sequence or an enhanced navigator-gated 3D SPGR (eNAV-3D-SPGR) sequence. No exogenous contrast agent was used. A 20-ms wait period was inserted between the 3D SPGR acquisition component and navigator component of the eNAV-3D-SPGR sequence to allow T1 recovery. Visual evaluation and calculation of the signal-to-noise ratio were performed to compare image quality between the imaging techniques. Result The eNAV-3D-SPGR sequence provided better noise properties than the cNAV-3D-SPGR sequence visually and quantitatively. Navigator gating with an acceptance window of 2mm effectively inhibited respiratory motion artifacts. The widening of the window to 6mm shortened the acquisition time but increased motion artifacts, resulting in degradation of overall image quality. Neither slice tracking nor incorporation of short breath holding successfully compensated for the widening of the window. Conclusion The eNAV-3D-SPGR sequence with an acceptance window of 2mm provides high-quality 3D SPGR images of the liver. [ABSTRACT FROM AUTHOR]