Kyo Itoh

Posterior Lobe of the Pituitary in Diabetes Insipidus: Mr Findings

The posterior lobe of the pituitary gland was evaluated by 1.5 T magnetic resonance (MR) in five cases of diabetes insipidus (DI), including one primary (idiopathic) and four secondary DI cases due to germinomas (two), teratoma (one), and histiocytosis χ (one). The normal posterior lobe displays high signal indistinguishable from fatty tissue on T1-weighted images (T1WI) (short T1 value). In all five DI cases the normal high signal of the posterior lobe was not detected in the pituitary fossa on T1WI. Hence, because of this characteristic finding, MR may greatly assist in the diagnosis of DI. We may speculate that the short T1 value of the posterior lobe is closely related to its functional integrity and may be due to the neurosecretory materials in the axons of the hypothalamohypophyseal tract.

Anterior and Posterior Lobes of the Pituitary Gland; Assessment by 1.5 T MR Imaging

Pituitary glands of 60 normal volunteers (30 men 20–36 years old, and 30 women 18–42 years old) were studied by 1.5 T magnetic resonance (MR) imaging. The T1-weighted images (T1WI) [repetition time (TR) = 400 ms; echo time (TE) = 25 ms] were obtained in the coronal, sagittal, and axial planes. Proton density (PD)/T2-weighted images (PDW1/T2WI) (TR = 2,000 ms; TE = 25/100 ms) were obtained in the sagittal plane using 3 mm slice thickness. On T1WIs of all subjects the posterior part (PP) of the pituitary fossa showed the highest signal, which was indistinguishable from fatty tissue. This study reveals that this region of high signal intensity (PP) corresponds to the posterior lobe and not intrasellar fat because (a) its shape, size, and position are compatible with the posterior lobe; (b) its signal intensity differs from that of fatty tissue on PDWI and T2WI; (c) the absence of an intrinsic chemical shift artifact (CSA) characteristic of fat; and (d) due to CSA, a dorsum with fatty marrow is shifted relative to the PP (or may be made to merge with it). Regarding the differentiation of the two lobes of the pituitary gland on MR, the morphology of the anterior and posterior lobes was evaluated and great variation found. Appreciation of normal is particularly important in evaluating coronal images for small pituitary lesions.

Endoscopic management of biliary strictures after duct-to-duct biliary reconstruction in right-lobe living-donor liver transplantation

Background. The aims of this study were to characterize the features of the biliary strictures that occur after duct-to-duct biliary reconstruction during right-lobe living-donor liver transplantation (LDLT) and to evaluate the feasibility of correcting such stricture endoscopically by inserting an “inside stent,” that is, a short internal stent, above the sphincter of Oddi. Methods. Biliary stricture occurred in 26 (35.6%) of 73 consecutive patients who underwent right-lobe LDLT with duct-to-duct biliary reconstruction from July 1999 through October 2001 and survived for more than 3 months. Of the 26 patients who had biliary stricture, 22 were referred for endoscopic retrograde cholangiography (ERC) and 4 for percutaneous cholangiography. Results. ERC disclosed biliary stricture in 19 (86.4%) of the 22 patients who underwent the procedure. One patient had an unbranched stricture, 16 had a fork-shaped stricture, 1 had a trident-shaped stricture, and 1 had a stricture with more than three branches. Fourteen (73.7%) of the patients with strictures were treated endoscopically by inserting inside stents ranging from 7 F to 12 F in size, three underwent a Roux-en-Y hepaticojejunostomy to repair their stricture, and two were closely observed as outpatients. Of the 14 patients who were treated with the inside-stent, only 1 had acute cholangitis immediately after the procedure and underwent a Roux-en-Y hepaticojejunostomy. The other 13 patients who were treated with the inside stent have not required surgical repair for as long as an average of 586 days. Conclusion. Endoscopic placement of an inside stent is useful for treating biliary strictures in patients who have undergone right-lobe LDLT with duct-to-duct reconstruction.

Cholangitis and Liver Abscess after Percutaneous Ablation Therapy for Liver Tumors: Incidence and Risk Factors

PURPOSE To determine the risk factors of cholangitis and liver abscess occurring after percutaneous ablation therapy for liver tumors. MATERIALS AND METHODS Between October 1995 and September 2002, 358 patients with 455 liver tumors underwent a total of 683 ablation procedures, such as percutaneous ethanol injection (PEI), percutaneous microwave coagulation (PMC), and radiofrequency (RF) ablation therapy. With a retrospective review of medical records, the rates and outcomes of cholangitis and/or liver abscess occurring after ablation therapy were evaluated. The relationship between cholangitis and/or liver abscess and multiple variables (age, disease, Child-Pugh class, size of nodules, multiplicity of nodules, history of transcatheter arterial embolization, presence of bilioenteric anastomosis, and lack of prophylactic antibiotics administration) were statistically analyzed. RESULTS Cholangitis and/or liver abscess occurred in 10 sessions (1.5%) in 10 patients: six sessions after PEI, three sessions after PMC, and one session after RF ablation. Both cholangitis and liver abscess were noted in seven sessions, cholangitis was noted in two, and liver abscess was noted in one. Six patients recovered, but two developed recurrent cholangitis and liver abscess, one developed lung abscess complicated with liver abscess, and one died of septic shock associated with cholangitis. On stepwise regression analysis, bilioenteric anastomosis was the sole significant predictor of cholangitis and/or liver abscess formation (P <.001; odds ratio = 36.4; 95% CI = 9.67-136.9). CONCLUSION Bilioenteric anastomosis strongly correlated with the development of cholangitis and/or liver abscess after percutaneous ablation therapy. Close posttreatment attention should be paid to this subgroup of patients.

Background and clinical impact of tissue congestion in right-lobe living-donor liver grafts: a magnetic resonance imaging study.

Background. Although right‐lobe liver grafts from living donors have been widely accepted as an option for adult patients, impact of middle hepatic vein (MHV) deprivation is a recent controversy. Methods. Fifty recipients of right‐lobe living‐donor liver grafts without MHV or drainage reconstruction in anterior segment were evaluated for posttransplant tissue congestion with T2‐weighted magnetic resonance imagings. Age of recipients and donors ranged from 19 to 69 (median 50) and 19 to 64 (46) years, respectively. Graft‐to‐recipient weight ratio ranged from 0.74% to 1.66% (1.06%). Cavoplasty was provided during right hepatic vein reconstruction to avoid anastomotic stricture. Results. Congestion was observed in 88% of segments V and 85% of segments VIII in the first month. Congestion positively correlated with anatomic dependency on MHV. Also, donors were significantly older in age in grafts with more congestion. However, congestion improved within several months in most grafts. Graft congestion was associated neither with morbidities nor with graft loss except for temporary correlation with ascites production in the third and fourth posttransplant weeks. Conclusion. A significant proportion of right‐lobe liver grafts without MHV experience morphologic congestion of the anterior segment in the early phase after transplantation, which is dependent on venous anatomy and donor age. However, the congestion spontaneously resolves in most cases. These results suggest that reconstruction of drainage vein(s) from the anterior segment is not necessary for all grafts provided good outflow through compensatory routes is secured. Additional reconstruction may be indicated in grafts with marginal size, anatomy, and quality.

Treatment of ruptured hepatocellular carcinoma.

AbstractBackground. The problem of whether surgical or conservative treatment is indicated for ruptured hepatocellular carcinoma (HCC) has not been analyzed from the viewpoint of long-term development of hepatitis viral infection from liver fibrosis to liver cirrhosis. Although transcatheter arterial embolization (TAE) for hemostasis followed by two-stage hepatectomy has been established as the best treatment for ruptured HCC, there still remain difficulties in the treatment of some patients. Methods. Twelve patients with ruptured HCC who were surgically or conservatively treated were retrospectively analyzed in terms of modality of treatment, liver function, extension of HCC, complications, survival rate, and cause of death. Results. Tumor rupture can occur either in the early phase or in the terminal phase during the development from liver fibrosis to liver cirrhosis, while tumor rupture occurs at the advanced stage in terms of HCC extension. TAE for emergent hemostasis or prevention of re-bleeding was performed in ten patients, while TAE was contraindicated in one patient and emergent laparotomy for hemostasis was performed in one patient. In four patients, elective extended surgical resection was performed, because liver function was evaluated as clinical stage 1 according to the General rules for the clinical and pathological study of primary liver cancer of the Liver Cancer Study Group of Japan. In seven patients, conservative or medical treat-ment was selected, because liver function was evaluated as poor. The surgically treated group, who could tolerate extensive operation, survived longer than the conservatively treated group. Conclusions. While TAE remains the best method to employ for hemostasis, it still has limitations. Hence, we should be mindful of other possible modalities for hemostasis and their outcomes. Rupture of HCC at an early phase in the development of liver fibrosis is a good indication for elective surgical treatment and should be distinguished from rupture in the terminal phase of liver cirrhosis, which should be treated conservatively. Although elective surgical treatment can be performed in selected patients, tumor size and location of HCC, in addition to liver function, should be taken into consideration.

Evaluation of pancreatic islet cell tumors by fluorine-18 fluorodeoxyglucose positron emission tomography: comparison with other modalities.

PURPOSE Pancreatic islet cell tumors are potentially malignant tumors and are often difficult to detect with current imaging modalities. Positron emission tomography (PET) using fluorine-18-labeled fluorodeoxyglucose (FDG) is an imaging technique with high sensitivity for malignant tumors. The aim of this study was to assess the feasibility of FDG PET to detect pancreatic islet cell tumors. METHODS Nineteen lesions of histologically proved islet cell tumors were evaluated in 12 patients (5 men, 7 women; ages 22 to 77 years). FDG uptake was analyzed semiquantitatively as a standardized uptake value. The diagnostic accuracy of PET was compared with that of US, CT, and MRI. RESULTS Of 19 lesions, 8 showed positive PET results (standardized uptake value > 2.3), and localization was indicated in 2 lesions. In nine tumors that were not detected by PET, seven were small tumors ranging from 1.5 to 8 mm in diameter and were not identified by other imaging methods. The sensitivity rate of PET was 53%, whereas those of US, CT, and MRI were 53%, 50%, and 53%, respectively. CONCLUSION Our data suggest that FDG PET has a limitation in that it does not detect some small-sized islet cell tumors, mainly depending on their size, but it has potential utility as a complementary modality for other imaging techniques.

Mr Imaging of Cavernous Hemangioma of the Face and Neck

Four patients with cavernous hemangioma of face and neck were evaluated with magnetic resonance imaging. Pathologically, soft tissue cavernous hemangiomas are characterized by small feeding arteries and large blood poolings. Arteriography usually fails to demonstrate the extent of the lesion. Computed tomography does not allow differentiation between these lesions and surrounding normal tissues. Magnetic resonance clearly demonstrates hemangiomas with good contrast between lesion and normal tissues. Spin-echo technique with long echo time appears to be particularly useful to delineate these lesions.

Prognostic Value of Pretreatment 18F-FDG PET/CT Parameters Including Visual Evaluation in Patients With Head and Neck Squamous Cell Carcinoma

OBJECTIVE The purpose of this study was to determine whether pretreatment quantitative and visual parameters seen on PET/CT using (18)F-FDG add prognostic information for clinical staging in patients with head and neck cancer. MATERIALS AND METHODS We enrolled 108 patients with histologically proven oral, oropharyngeal, hypopharyngeal, and laryngeal squamous cell carcinomas who underwent FDG PET/CT before treatment and, later, definitive therapy in our study. PET/CT parameters-maximum standardized uptake value (SUVmax), metabolic tumor volume (MTV), total lesion glycolysis (TLG), and uptake pattern (sphere-shaped or ring-shaped)-were recorded. The prognostic value of these parameters was evaluated using univariate and multivariate Cox regression analyses. RESULTS In the univariate analysis, all of the FDG PET/CT parameters--SUVmax (> 10 g/mL) of the primary tumor, MTV (> 20 cm(3)), TLG (> 70 g), and uptake pattern (ring-shaped)--were significantly associated with negative effects on disease-specific survival (DSS) and disease-free survival (DFS). In the multivariate analysis, the MTV and uptake pattern remained associated with DSS after corrections for the Union for International Cancer Control (UICC) stage and definitive therapy (p = 0.023 and < 0.001, respectively). Another multivariate model that included MTV as a continuous variable, uptake pattern, and UICC stage showed that the uptake pattern remained significantly associated with DSS, whereas the association between DSS and MTV was not significant (p < 0.001 and = 0.332, respectively). CONCLUSION Our data indicate that the pretreatment PET/CT parameters had prognostic value. In particular, a qualitative factor, uptake pattern, provided better prognostic information to the clinical staging of head and neck squamous cell carcinomas than the other PET/CT parameters.

Posterior lobe of the pituitary: identification by lack of chemical shift artifact in MR imaging

The posterior aspect of the normal sellar content usually displays high intensity signal on T1-weighted images. The shape, size, and location of this high intensity seem to be compatible with the posterior lobe of the pituitary gland. But fatty tissues such as intrasellar fat pad or fatty marrow of the dorsum sellae or both must be excluded as other possible sources of this high intensity signal. Two sellar phantoms were prepared. Both included high intensity posterior parts, one due to high concentration of a paramagnetic ion and the other due to fat. Magnetic resonance imaging of these phantoms showed that the fatty component was accompanied by distinct chemical shift artifacts in a predictable way. The absence of chemical shift artifact in the sellar content of normal volunteers excluded the fatty tissue as representing the high intensity posterior part. The high intensity posterior part of the normal sellar content appears to represent the posterior lobe of the pituitary gland.