Daisuke Kakihara

Diffusion-weighted echo-planar MR imaging and ADC mapping in the differential diagnosis of ovarian cystic masses: Usefulness of detecting keratinoid substances in mature cystic teratomas

To elucidate whether apparent diffusion coefficient (ADC) values calculated from echo‐planar diffusion‐weighted MR imaging (EPDWI) are useful in the differential diagnosis of ovarian cystic masses.

Natural history of pancreatic intraductal papillary mucinous tumor of branch duct type: follow-up study by magnetic resonance cholangiopancreatography.

Objective: The purpose of this study was to elucidate the natural history of branch duct type pancreatic intraductal papillary mucinous tumor (IPMT) by evaluating serial changes in the magnetic resonance cholangiopancreatography (MRCP) findings of patients diagnosed with pancreatic IPMT of branch duct type. Methods: Thirty-five patients had branch duct type IPMT, including 9 patients with separate lesions, and underwent initial and follow-up MRCP over a period of more than 12 months. The maximum diameter of the cystic lesion, the presence of associated main pancreatic duct (MPD) dilatation, and the presence of a filling defect were evaluated. Serial changes in these findings were analyzed. Results: Tumor enlargement on follow-up MRCP was observed in 7 cases. Of the 29 branch duct IPMTs without associated MPD dilatation or a filling defect identified on initial MRCP, only 1 showed gradual tumor enlargement. In 4 cases, the cyst size decreased on follow-up MRCP. Conclusions: Branch duct type IPMTs grow slowly and can be monitored without operation provided that the tumor shows no associated MPD dilatation or filling defect.

Diagnostic performance of apparent diffusion coefficient for predicting histological grade of hepatocellular carcinoma

OBJECTIVE To investigate whether the histological grade of hepatocellular carcinoma (HCC) can be predicted using the apparent diffusion coefficient (ADC). MATERIALS AND METHODS This retrospective study group consisted of 80 patients with 85 surgically resected HCCs who underwent preoperative MRI exams including diffusion-weighted imaging. The tumors were histologically classified into five groups as follows: five well (w-), 17 well to moderately (wm-), 37 moderately (m-), 16 moderately to poorly (mp-), and 10 poorly (p-) differentiated HCCs. For ADC measurement of each HCC, the largest possible region of interest was placed on the solid region on the ADC map where ADC was considered to be the lowest. The average ADCs of the five histological grades were compared using Spearmans rank correlation test and Students t-test, and the diagnostic performance of ADC for mp- and p-HCCs was also evaluated using a receiver operating characteristic-based positive test. RESULTS The average ADC of p-HCC (0.76±0.10×10(-3) mm2/s) was significantly lower than those of the other four histological grades. The average ADC of mp-HCCs (0.99±0.20×10(-3) mm2/s) was significantly lower than those of w-, wm- and m-HCCs. The sensitivity, specificity, PPV, NPV, and accuracy, when an ADC of 0.972 or lower was considered an indicator of mp- and p-HCCs, were 73.1%, 72.9%, 54.3%, 86.0% and 72.9%, respectively. CONCLUSION ADCs of mp- and p-HCCs were lower than those of w-, wm- and m-HCCs. ADC can contribute to radiological diagnosis of poorly differentiated components in HCCs.

Usefulness of the calculated apparent diffusion coefficient value in the differential diagnosis of retroperitoneal masses

To elucidate whether or not the apparent diffusion coefficient (ADC) values calculated from echo‐planar diffusion‐weighted (EPDW) MR images are useful in the differential diagnosis of retroperitoneal masses.

Radiologic Detectability of Minute Portal Venous Invasion in Hepatocellular Carcinoma

OBJECTIVE The objective of this study was to evaluate whether minute portal venous invasion in hepatocellular carcinoma (HCC) can be diagnosed radiologically. MATERIALS AND METHODS CT hepatic arteriography and CT with arterioportography (CTAP) of 15 patients with minute portal venous invasion (group 1) and 30 patients without it (group 0) were evaluated. An area showing low attenuation on CTAP and high attenuation on CT hepatic arteriography around the tumor was defined as an area of peritumoral hemodynamic change. The shape and size of the area were compared between the two groups. The ratio of the area of peritumoral hemodynamic change volume to tumor volume (area volume-tumor volume ratio) was used as an indicator of the size of the area of peritumoral hemodynamic change and was categorized as one of three grades: grade I, 10% or less; grade II, between 10% and 30%; and grade III, 30% or more. The detectability of minute portal invasion was assessed when grade III was considered as an indicator. Each comparison was also made independently when the tumor diameter either was limited to less than 3 cm or was 3 cm or more. RESULTS Three types of area of peritumoral hemodynamic change were identified: wedge-shaped, belt-shaped or irregular, and linear. No significant difference in the frequency of each type of area of peritumoral hemodynamic change was observed between the two groups. The area volume-tumor volume ratio in group 1 was larger than that in group 0, with statistical significance when the tumor diameter was less than 3 cm (p = 0.046). Positive and negative predictive values were 71.4% and 75.0%, respectively, when the tumor diameter was less than 3 cm. CONCLUSION The area of peritumoral hemodynamic change in HCC patients with minute portal invasion (group 1) may be larger than in those without it (group 0), especially when tumors are small.

Fitz-Hugh-Curtis syndrome. Radiologic manifestation.

Objectives To clarify radiologic findings of Fitz-Hugh-Curtis syndrome (FHCS). Methods Thirteen women with right upper abdominal pain who were clinically diagnosed with FHCS were included. Biphasic helical computed tomography (CT) of the abdomen was performed in all patients. Posttherapeutic follow-up CT was available in 7 patients. Ultrasonography (US) was also performed in 12 patients. These imaging findings were reviewed retrospectively. Results On enhanced CT, hepatic and splenic capsular enhancement was identified in 13 and 4 patients, respectively. Hepatic capsular enhancement on the early phase, which was detected in all patients, disappeared after treatment. No adhesive band or fluid collection around the liver was evident. No enhancement of the “bare area” of the liver and spleen was seen. No definite abnormality of the liver or perihepatic region was detected by US. Conclusions Hepatic and splenic capsular enhancement on abdominal enhanced CT may be characteristic of FHCS. Enhanced CT may be a useful and noninvasive modality to help a diagnosis of FHCS, especially in young women with right upper abdominal pain without significant findings on US and gastrointestinal endoscopy.

MR prediction of liver fibrosis using a liver-specific contrast agent: Superparamagnetic iron oxide versus Gd-EOB-DTPA.

To examine whether the uptake of a liver‐specific contrast agent in the liver parenchyma was correlated with the degree of liver fibrosis.

Papillary renal carcinoma: Diagnostic approach by chemical shift gradient-echo and echo-planar MR imaging

To elucidate whether MRI can detect fat in interstitial histiocytes and hemosiderin (Hs) deposition (both of which are histological characteristics of papillary renal carcinoma (RCpap)) within RCpap.

Hypovascular hepatic nodule showing hypointensity in the hepatobiliary phase of gadoxetic acid-enhanced MRI in patients with chronic liver disease: Prediction of malignant transformation

PURPOSE To investigate the predictive factors of malignant transformation of hypovascular hepatic nodule showing hypointensity in the hepatobiliary phase images of gadoxetic acid-enhanced MRI (HHN). MATERIALS AND METHODS The clinical data and imaging findings of dynamic contrast-enhanced computed tomography (DCE-CT) and gadoxetic acid-enhanced MRI for a total of 103 HHNs in 24 patients with chronic liver disease were retrospectively investigated. After the results of follow-up examinations were investigated, HHNs were categorized into the three groups for each comparison: (1) nodules with enlargement and/or vascularization and others, (2) nodules with only enlargement and others, (3) nodules with only vascularization and others. Enlargement and/or vascularization during the follow-up period were defined as malignant transformation of HHN. The frequency of each clinical datum and imaging finding in each group was compared to identify the predictive factors for malignant transformation in HHN. RESULTS Multivariate analysis showed that a nodule size of 9 mm or more on the initial gadoxetic acid-enhanced MRI was a significant predictive factor for the enlargement and/or vascularization of HHN (P<0.05). On the other hand, the hypoattenuation on the delayed phase imaging of the initial DCE-CT was a significant predictive factor for the enlargement or vascularization of HHN (P<0.05). CONCLUSION A nodule size of 9 mm or more on the initial gadoxetic acid-enhanced MRI and hypoattenuation on the delayed phase imaging of initial DCE-CT would be helpful for predicting the outcome of HHN in patients with a risk of hepatocellular carcinoma.

Imaging of cholangiolocellular carcinoma of the liver

AIM Cholangiolocellular carcinoma (CoCC) is currently considered to originate from hepatic progenitor cells. The purpose of this study was to evaluate the imaging features of cholangiolocellular carcinoma of the liver. MATERIALS AND METHODS Five cases of surgically resected cases of CoCC from 4 institutions were retrospectively evaluated. All of the five patients underwent contrast-enhanced dynamic CT. MRI and angio-CT including CT during arterioportography (CTAP) and CT during hepatic arteriography were performed in 3 and 2 patients, respectively. Histological evaluation was also performed and was correlated with radiographic findings. RESULTS On dynamic CT or MRI, the lesions presented hypervascular tumors with delayed washout in 2 cases and in the other 3 cases, the lesions showed peripheral enhancement with concentric delayed filling. On CTAP, the continued existence of portal veins or tiny spots of portal flow was identified in the tumors. Fibrous capsule or tumor necrosis was not observed. CONCLUSION CoCC tumors have the dual imaging characteristics of hepatocellular carcinoma and cholangiocarcinoma. The absence of a fibrous capsule, the absence of tumor necrosis, peripheral location within the liver, and the presence of portal venous penetration within the tumor also appear to be characteristic features.