Masato Tanikake

Detection and evaluation of pelvic lymph nodes in patients with gynecologic malignancies using body diffusion-weighted magnetic resonance imaging.

Background: In this study, the potential in detecting and evaluating pelvic lymph node metastases on body diffusion-weighted (DW) images was evaluated in patients with gynecologic malignancies. Methods: This study included 18 patients with gynecologic malignancy who underwent magnetic resonance imaging in the pelvis using a 1.5-T superconductive magnet. The identification of pelvic nodes on only T2-weighted (T2W) axial images and on DW axial images in addition to T2W axial images was examined and compared. Moreover, we measured and calculated a short-axis diameter, a long-axis diameter, and a ratio of short- and long-axis diameter of nodes on the T2W images and the apparent diffusion coefficient (ADC) values of the nodes on the DW images. These results were compared with histopathologic results. Results: First, 136 (40%) of 340 dissected nodes were identified on T2W images, and 249 (73%) of 340 dissected nodes were identified on DW images in addition to T2W images. Second, the differences in the short-axis diameter, the long-axis diameter, and the ratio of short- and long-axis diameter on T2W images between metastatic and nonmetastatic nodes were not significant. The differences in the ADC values between metastatic and nonmetastatic nodes were not significant. Conclusions: Body DW images are useful in detection of pelvic lymph nodes in patients with gynecologic malignancy. However, the measurement of ADC values does not contribute to a diagnosis of metastatic nodes.

Body diffusion-weighted MR imaging of uterine endometrial cancer: Is it helpful in the detection of cancer in nonenhanced MR imaging?

OBJECTIVE In this study, the authors discussed the feasibility and value of diffusion-weighted (DW) MR imaging in the detection of uterine endometrial cancer in addition to conventional nonenhanced MR images. METHODS AND MATERIALS DW images of endometrial cancer in 23 patients were examined by using a 1.5-T MR scanner. This study investigated whether or not DW images offer additional incremental value to conventional nonenhanced MR imaging in comparison with histopathological results. Moreover, the apparent diffusion coefficient (ADC) values were measured in the regions of interest within the endometrial cancer and compared with those of normal endometrium and myometrium in 31 volunteers, leiomyoma in 14 patients and adenomyosis in 10 patients. The Wilcoxon rank sum test was used, with a p<0.05 considered statistically significant. RESULTS In 19 of 23 patients, endometrial cancers were detected only on T2-weighted images. In the remaining 4 patients, of whom two had coexisting leiomyoma, no cancer was detected on T2-weighted images. This corresponds to an 83% detection sensitivity for the carcinomas. When DW images and fused DW images/T2-weighted images were used in addition to the T2-weighted images, cancers were identified in 3 of the remaining 4 patients in addition to the 19 patients (overall detection sensitivity of 96%). The mean ADC value of endometrial cancer (n=22) was (0.97+/-0.19)x10(-3)mm(2)/s, which was significantly lower than those of the normal endometrium, myometrium, leiomyoma and adenomyosis (p<0.05). CONCLUSION DW imaging can be helpful in the detection of uterine endometrial cancer in nonenhanced MR imaging.

Dual-Phase 3D CT Angiography During a Single Breath-Hold Using 16-MDCT: Assessment of Vascular Anatomy Before Laparoscopic Gastrectomy

OBJECTIVE In this study, we evaluated the efficacy of dual-phase 3D CT angiography (CTA) during a single breath-hold using 16-MDCT in the assessment of vascular anatomy before laparoscopic gastrectomy. MATERIALS AND METHODS The study involved 20 consecutive patients (10 men, 10 women; mean age, 59 years) scheduled for laparoscopic gastrectomy for the treatment of early gastric cancer. A dual-phase contrast-enhanced CT scan using 16-MDCT was obtained before laparoscopic gastrectomy. After rapid infusion of a nonionic contrast agent, arterial and venous phase scans were obtained serially with an interval of 15 sec during a single breath-hold of 31 sec. Three-dimensional CTA images in the arterial phase (3D CT arteriography) and venous phase (3D CT venography) were individually reconstructed using the volume-rendering technique, and then the images were fused together. We evaluated the detectability of the celiac trunk, left gastric artery (LGA), right gastric artery (RGA), left gastric coronary vein (LCV), Henles gastrocolic trunk, right gastroepiploic vein (RGEV), and accessory right colic vein on 3D CTA to compare with surgical findings. RESULTS In all 20 patients, 3D CT arteriography and venography clearly showed the celiac trunk, LGA, RGA, Henles gastrocolic trunk, RGEV, and accessory right colic vein, which were correctly identified during surgery. The branching pattern of the celiac trunk was classified as Michels type I in 19 patients and Michels type II in one patient. Imaging showed the RGA originating from the proper hepatic artery (PHA) in nine patients; from the gastroduodenal artery (GDA) in seven patients; and from the left hepatic artery (LHA) in four patients. In 12 patients, the LCV joined the portal vein (PV) and in eight, the splenic vein (SV). In all patients, the accessory right colic vein joined the RGEV, and Henles gastrocolic trunk proximal to the joining point flowed to the superior mesenteric vein (SMV). In all 20 patients, the fused image simultaneously showed arteries and veins around the stomach, with no mismatch between the arterial and venous phase images. In 10 patients, the LCV joined the PV after running along the dorsal side of the PHA, common hepatic artery (CHA), or splenic artery (SA). In eight patients, the LCV joined the SV after running along the ventral side of the PHA, CHA, or SA. In two patients, the LCV joined the PV after running along the ventral side of the CHA, which correlated with the surgical findings. Both the sensitivity and positive predictive values of 3D CTA revealed 100% correct identification of the celiac trunk, LGA, RGA, LCV, Henles gastrocolic trunk, RGEV, and accessory right colic vein. CONCLUSION Dual-phase 3D CTA using 16-MDCT clearly revealed individual arteries and veins around the stomach before laparoscopic gastrectomy. The fused image of 3D CT arteriography and venography during a single breath-hold enabled the simultaneous assessment of arteries and veins before laparoscopic gastrectomy.

Preoperative Evaluation of Local Invasion and Metastatic Lymph Nodes of Colorectal Cancer and Mesenteric Vascular Variations Using Multidetector-Row Computed Tomography Before Laparoscopic Surgery

Objective: To evaluate local invasion and lymph nodes metastasis of colorectal cancer and mesenteric vascular variations using multidetector-row computed tomography (MDCT) before laparoscopic colorectal surgery. Methods: Fifty-one patients with colorectal cancer underwent MDCT. The evaluation items were as follows: (1) local invasion; (2) detected lymph nodes evaluated by short-axis diameter, long-axis diameter, short/long axis diameter ratio, and computed tomography (CT) attenuation; and (3) visualization of mesenteric artery and vein by 3-dimensional-CT angiography. Results: First, in the evaluation of local invasion, overall accuracy was 94.1%. Second, the point of 0.8 or greater in short/long-axis diameter ratio was best index for the diagnosis of metastatic lymph nodes. Using this index, the accuracy of the diagnosis per node was 80.5%. Third, 3-dimensional-CT angiography correctly demonstrated variations of the mesenteric artery and vein. Conclusions: The MDCT was effective for evaluation of local invasion and lymph nodes metastasis of colorectal cancer and mesenteric vascular variations before laparoscopic surgery.

CT findings of small bowel strangulation: the importance of contrast enhancement.

The purpose of this study is to illustrate computed tomography (CT) findings suggestive of small bowel strangulation. We have performed the precontrast and postcontrast CT with single and multidetector CT scanners and evaluated the bowel wall changes and mesentery changes and correlated them with the operative findings. The direct CT findings suggestive of small bowel strangulation included high-density bowel wall on precontrast scans; lack of, or diminished contrast enhancement of the involved bowel wall; localized mesenteric fluid accumulation (mesenteric congestion); and localized pneumatosis. The indirect CT signs included C- or U-shaped loops with mesenteric vessels converging toward the obstruction site, ascites, target sign, two adjacent collapsed round loops, and whirl sign. We particularly emphasize the importance of contrast enhancement of bowel mucosa for early diagnosis to differentiate strangulation from a mechanical obstruction without bowel ischemia, and also the importance to differentiate proximal secondary gas-filled dilated small bowel loops from distal primary involved fluid-filled small bowel loops because these two types of small bowel loops are present in the single peritoneal cavity. As early recognition of small bowel strangulation may help improve the patient outcome because the involved bowel loops can be preserved without resection, it is essential to become familiar with the CT signs suggested small bowel obstruction strangulation.

Virtual CT colectomy by three-dimensional imaging using multidetector-row CT for laparoscopic colorectal surgery

Laparoscopic colorectal surgery has been attracting attention for its capacity to improve the quality of life (QOL) of patients. However, there are disadvantages to this approach, namely, it is difficult to obtain an image of the entire view of the operative field, and organs and lesions cannot be manipulated directly by the surgeon during surgery. For this reason, it takes a relatively large amount of time to ligate vessel, which can vary between patients. Furthermore, vessels and organs can be damaged during lymph nodes dissection under laparoscopic guidance, leading to heavy bleeding that prevents the surgeon from having access to a good view of the operative field. Then, to assess preoperatively the vascular anatomy, we carried out multiphase, contrast-enhanced examinations using multidetector-row CT (MDCT) on patients with colorectal cancer, and prepared the fused image of 3D images of arteries, veins, the colorectum, organs, and tumor. We called the utilization of 3D imaging virtual CT colectomy, which contributed to rapid and safe manipulation of the origins of the arteries and the veins, as well as lymph nodes dissection, without incurring injury to the involved arteries and veins.

Hepatic Computed Tomography for Simultaneous Depiction of Hepatocellular Carcinoma, Intrahepatic Portal Veins, and Hepatic Veins in Real-time Virtual Sonography Initial Experience

The aim of this study was to examine a double‐step injection of contrast material in hepatic computed tomography (CT) for the simultaneous depiction of hepatocellular carcinoma (HCC), intrahepatic portal veins, and hepatic veins in real‐time virtual sonography.

Effect of Saline Pushing after Contrast Material Injection in Abdominal Multidetector Computed Tomography with the Use of Different Iodine Concentrations

Purpose: To investigate whether saline pushing after contrast material improves hepatic vascular and parenchymal enhancement, and to determine whether this technique permits decreased contrast material concentration. Material and Methods: 120 patients who underwent hepatic multidetector computed tomography were divided randomly into four groups (Groups A–D): receiving 100 ml of contrast material (300 mgI/ml) only (A) or with 50 ml of saline solution (B); or 100 ml of contrast material (350 mgI/ml) only (C) or with 50 ml of saline solution (D). Computed tomography (CT) values of the aorta in the arterial phase, the portal vein in the portal venous inflow phase, and the liver in the hepatic phase were measured. Visualization of the hepatic artery and the portal vein by 3D CT angiography was evaluated as well. Results: Although the enhancement values of the aorta were not improved significantly with saline pushing, they continued at a high level to the latter slices with saline pushing. The enhancement value of the portal vein increased significantly and CT portography was improved with saline pushing. The enhancement value of the liver was not improved significantly using saline pushing. In a comparison between groups B and C, the enhancement values of the aorta and portal vein and the visualization of CT arteriography and portography were not statistically different. Conclusion: The saline pushing technique can contribute to a decrease in contrast material concentration for 3D CT arteriography and portography.

Virtual CT gastrectomy by three-dimensional imaging using multidetector-row CT for laparoscopic gastrectomy

Key words: Virtual computed tomographic gastrec-tomy—Multidetector row computed tomogra-phy—Three-dimensional imaging—Multiphase fusionimaging—LaparoscopicgastrectomyLaparoscopicsurgeryhasgainedwideclinicalacceptancein various surgical practices and has become the goldstandard for cholecystectomy, Nissen fundoplication,and adrenal surgery. In 1994, the first laparoscopicallyassisted Billroth I gastrectomy was reported, and cur-rently a laparoscopic distal gastrectomy is commonlyperformedforearlystagegastriccancer[1].Thebenefitsof the laparoscopic approach include smaller surgicalincisions, less intraoperative blood loss, faster recoveryfor normal bowel function, and shorter hospital staysthaninthecaseofconventionalopensurgery[1–4].However, despite the advantages of this procedure,thereremainseveraldisadvantages:limitedimagesoftheentire operative field under laparoscopy and a lack oftactilesensationinterferewithdirectmanipulationbythesurgeonduringtheprocedure.Forthisreason,ittakesalongtimetoidentifythepropervesselswheretheremaybe major variations in each patient [2]. Moreover,arteriesrunalongoracrossveinsaroundthestomachina complicated fashion; therefore, veins can be injuredduring the dissection of lymph nodes along the arteriesandtheligationofarteriesunderlaparoscopicguidance,whichleadstoheavybleedingthatpreventsthesurgeonfromhavingaccesstoagoodviewoftheoperativefield[3].Therefore,itisquiteimportanttoperformapreop-erative assessment of vascular anatomy around thestomach using three-dimensional (3D) computed tomo-graphic(CT)angiography,whichcanbeveryhelpfultoachieve the safe and rapid ligation of vessels and dis-sectionoflymphnodes[5–9].We performed contrast-enhanced examinations atarterial and venous phase using 4 or 16 multidetector-rowCT(MDCT)beforealaparoscopicgastrectomyandslicedatafromtheindividualphaseswereconvertedintoa 3D imaging format using a volume-rendering tech-nique.Weusedthefusedimageof3Dimagesofarteriesand veins around the stomach for preoperative assess-ment and called the use of 3D imaging virtual CT gas-trectomy[5–9].In this study, we examined the usefulness of virtualCT gastrectomy for laparoscopic gastrectomy and,moreover, introduced our preliminary study of the vir-tualCTnavigationofsentinellymphnodes.

Radiological diagnosis of large-bowel obstruction: nonneoplastic etiology

Large-bowel obstruction (LBO) is a relatively common abdominal emergency. Computed tomography (CT) diagnosis of LBO is often easy, but it is essential to clarify LBO etiology and to decide how to treat it. Therefore, it is important for the radiologist to become familiar with the imaging findings of LBO, including plain radiography and CT, to determine its various causes, as well as the many diseases mimicking LBO. In this article, we show the characteristics of radiological findings of plain radiograph, barium study, and CT and their correlations with pathologic findings. LBO etiology comprises two main categories: neoplastic and nonneoplastic disease. However, the primary causes of LBO are neoplastic etiologies, and nonneoplastic causes are relatively uncommon and unfamiliar to many radiologists in clinical practice. Therefore, in this review, we present nonneoplastic etiology of LBO and diseases simulating LBO and provide critical information concerning the causes of LBO and viability of the involved bowel loops.