This article is the English version of the Brain Chip hypothesis previously presented in the books “Brain Equation One Plus One (Kinokuniya, 2001)” and “Plus Alpha (Kinokuniya, 2002).” The concept in this article has been translated into English by the author himself in response to an overwhelming number of requests from colleagues outside Japan.

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Purpose: To determine the optimum imaging conditions for the balanced turbo field echo (bTFE) sequence in abdominal imaging, we performed phantom experiments and scanning of a normal volunteer while noting the correlation among signal intensity, k-space ordering, flow velocity and Gd-DTPA concentration.
Materials and Methods: Initially, the abdomen of a healthy volunteer and some samples (water, blood and bovine albumin solutions with various Gd-DTPA concentrations, and olive oil) were examined with the bTFE sequence under various conditions to define the correlation among signal intensity, k-space ordering and Gd-DTPA concentration. Another experiment was performed to assess the correlation between the flow velocity and Gd-DTPA concentration. With the centric-bTFE sequence, we measured the signal intensity of water samples having various Gd-DTPA concentrations flowing in a long tube with an internal diameter of 4 mm.
Results: The experiments revealed the following issues: (i) The contrast of bTFE images was much influenced by k-space ordering; (ii) Gd-DTPA did not exhibit an overt enhancement effect in water and blood under stable conditions; (iii) The signal intensity of moving water decreased in centric-bTFE images, and this signal drop became more significant as the fluid speed increased; and (iv) Gd-DTPA decreased the range of signal loss in the moving fluid; however, this effect had no correlation with Gd-DTPA concentration.
Conclusion: When the bTFE sequence was employed for abdominal imaging, centric view ordering, fat suppression and Gd-DTPA contrast enhancement were assumed to be necessary.

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Purpose: We performed MRI examinations of patients in order to confirm the enhancement effect of the balanced turbo field echo (bTFE) sequence with centric view ordering and SPIR (SPIR-centric-bTFE) as mentioned in the prior paper, and to evaluate the actual image quality of this sequence.
Materials and Methods: The upper abdomens of 30 patients with various abdominal disorders were examined with the SPIR-centric-bTFE sequence before and after Gd-DTPA administration. To assess the enhancement effect of Gd-DTPA, ROI measurements were taken in the aorta, superior mesenteric artery, portal vein, liver and bile juice in the common bile duct in each patient both in pre- and postcontrast images. Visual evaluations were also carried out in order to depict the peripheral vessels in the peritoneal fat and the apparent brightness of the soft-tissue organs.
Results: In all patients, the signal of the arteries after Gd-DTPA administration increased by about 50% compared with precontrast images. On the other hand, the veins and the liver showed a signal gain of less than 20% in postcontrast images. Consequently, only the signal of the arteries appeared enhanced in the postcontrast images. The visual evaluation revealed that postcontrast SPIR-centric-bTFE acquisition can depict the thin vessels clearly and the abdominal soft-tissue organs brightly.
Conclusion: The balanced turbo field echo sequence with centric view ordering and SPIR after Gd-DTPA injection was considered the most appropriate protocol when this sequence was employed for abdominal imaging.

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Purpose: The usefulness of diffusion-weighted imaging (DWI) in the field of neuroradiology has been established. Despite its high contrast resolution, DWI has the disadvantages of susceptibility artifact and chemical shift artifact. We performed DWI of breast cancer with the sensitivity encoding (SENSE) technique.
Methods: The subjects were 60 female patients with breast mass. All patients underwent MRI including SENSE-DWI and were diagnosed histologically. Of these patients, 55 were diagnosed with breast cancer and the remaining five were diagnosed with benign mass. The histological diagnoses of breast cancer were as follows: 39 cases of invasive ductal carcinoma (IDC); 11 cases of IDC with a predominant intraductal component and non IDC (pure or predominant NIDC); and five cases of special types of cancer. The MR system used was a Gyroscan Intera 1.5T (Philips Medical Systems). In addition to routine MRI for breast cancer, including contrast-enhanced dynamic, SENSE-DWI was obtained. The accuracy of the positional information of SENSE-DWI was visually compared with that of conventional images. The apparent diffusion coefficient (ADC) values of breast mass were analyzed with SENSE-DWI.
Results: The accuracy of positional information was adequate for diagnosing of all patients. The mean ADC value of breast cancer was 1.021×10^-3 mm²/s and that of benign mass was 1.488×10^-3 mm²/s (p=0.0002). The mean ADC value of IDC was 0.968×10^-3 mm²/s and that of pure or predominant NIDC was 1.218×10^-3 mm²/s (p=0.0011).
Conclusion: SENSE-DWI was of sufficient quality to support diagnosis of breast mass. SENSE-DWI may permit the acquisition of more detailed information about lesions, including tumor cellularity, that is difficult to obtain with conventional techniques.

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Purpose: The purpose of this study was to compare the performance of in-phase and opposed-phase gradient-recalled echo (GRE) pulse sequences in paramagnetic contrast-enhanced magnetic resonance (MR) imaging of hepatocellular carcinomas (HCCs) during the hepatic arterial phase.
Material and methods: Thirty-four patients with 84 lesions with known or suspected HCCs, nine of whom had a fatty liver, were examined with double-echo GRE techniques under 1.5T before and 30 s after injection of gadopentenate dimeglumine at a dose of 0.1 mmol/kg. Echo times were 2.4 ms (opposed phase) and 5.0 ms (in phase). Contrast enhancement of the HCC detected in both in-phase and opposed-phase images was evaluated. The liver signal-to-noise ratio (SNR), lesion-liver contrast-to-noise ratio (CNR), and enhancement ratio (ER) were calculated for the largest lesion of each patient.
Results: In dynamic gadolinium-enhanced images of the 84 HCCs, 81 (96.4%) were detected in both in-phase and opposed-phase images, two (2.4%) were detected in only in-phase images, and one (1.2%) was detected only in opposed-phase images. The liver SNR, CNR, and ER were 46.7±16.1, 15.2±10.3, and 0.637±0.268 for in-phase images, and 48.9±16.9, 16.3±11.8, and 0.647±0.309 for opposed-phase images, respectively. In patients with a fatty liver, the SNR, CNR, and ER were 46.0±18.1, 21.7±17.9, and 0.525±0.231 for in-phase images, and 44.3±18.7, 26.0±21.3, and 0.793±0.124 for opposed-phase images, respectively. No significant statistical differences were found between the in-phase and opposed-phase images.
Conclusion: Opposed-phase GRE imaging is equivalent to in-phase GRE sequences in patients with or without fatty liver for detection of HCC in dynamic gadolinium-enhanced images.

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The purpose of the current study is to evaluate the accuracy of MR thermometry for radiofrequency ablation (RFA) with hook-shaped electrodes. The objects were eight extracted bovine livers. The chemical shift change was calculated from MR images acquired with a spoiled gradient echo sequence and compared with the temperature directly measured with a thermocouple. Linear regression was established between them with a coefficient of -0.0110±0.0007 ppm/°C and errors were calculated as -0.50±7.50°C. MR thermometry is capable of monitoring temperature for RFA.

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We encountered two multicystic acoustic schwannomas with intratumoral hemorrhage. The radiological appearance in each case was similar to that obtained with CT and MRI. From a histological perspective, in each case we observed hypervascularity with thin-walled, dilated vessels in clusters and hemosiderin depositions around the dilated vessels.

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