11C-methionine positron emission tomography for target delineation of recurrent glioblastoma in re-irradiation planning.

AIM: To define the optimal margin on MRI scans in the re-radiation planning of recurrent glioblastoma using methionine positron emission tomography (MET-PET). BACKGROUND: It would be very useful if the optimal margin on MRI to cover the uptake area on MET-PET is known. MATERIALS AND METHODS: CT, MRI, and MET-PET were performed separately over the course of 2 weeks. Among the MRI scans, we used the contrast-enhanced T1-weighted images (Gd-MRI) and T2-weighted images (T2-MRI). The Gd-MRI-based clinical target volume (CTV) (CTV-Gd) and the T2-MRI-based CTV (CTV-T2) were defined as the contrast-enhanced area on Gd-MRI and the high intensity area on T2-MRI, respectively. We defined CTV x mm (x = 5, 10, 15, 20) as x mm outside the CTV. MET-PET-based CTV (CTV-MPET) was defined as the area of accumulation of MET-PET. We calculated the sensitivity and specificity of CTV-Gd and CTV-T2 following comparison with CTV-MPET, which served as the gold standard in this study. RESULTS: The sensitivity of CTV-T2 5 mm (98%) was significantly higher than CTV-T2 (87%), and there was no significant difference in the sensitivity between CTV-T2 5 mm and CTV T2 10, 15, or 20 mm. The sensitivity of CTV-Gd 20 mm (97%) was lower than that of CTV-T2 5 mm (98%). CONCLUSIONS: A margin of at least 5 mm around the high intensity area on T2-MRI is necessary in the target volume delineation of recurrent glioblastoma for the coverage of MET-PET findings in re-radiation therapy planning.

Treatment outcomes and late toxicities of intensity-modulated radiation therapy for 1091 Japanese patients with localized prostate cancer.

AIM: This study aimed to evaluate the treatment result of intensity-modulated radiation therapy (IMRT) in a large number of Japanese patients with prostate cancer. BACKGROUND: A total of 1091 patients with localized prostate cancer were recruited between March 2006 and July 2014. The patients were stratified into low- (n = 205 [18.8%]), intermediate- (n = 450 [41.2%]), high- (n = 345 [31.6%]), and very high-risk (n = 91 [8.3%]) groups according to the National Comprehensive Cancer Network classification. All patients were irradiated via IMRT at a dose of 74-78 Gy with or without androgen-deprivation therapy. The mean follow-up period was 50 months (range, 2-120 months). RESULTS: The biochemical failure-free rate (BFFR), the clinical failure-free rate, and the overall survival rate at the 5-year follow-up for all patients was 91.3%, 96.2%, and 99.1%, respectively. In univariate analysis, the prostate-specific antigen (PSA) levels (≤20 vs. >20 ng/ml) were significantly correlated with BFFR. A trend toward higher BFFR was noted in patients with a Gleason score (GS) of ≤7 than in patients with GS ≥8. In multivariate analysis, only PSA (≤20 vs. >20 ng/ml) was significantly correlated with BFFR. The cumulative incidence rate of gastrointestinal and genitourinary toxicity (≥grade 2) at the 5-year follow-up was 11.4% and 4.3%, respectively. CONCLUSIONS: The findings of this study indicate that IMRT is well tolerated and is associated with both good long-term tumor control and excellent outcomes in patients with localized prostate cancer.

Efficacy and safety of octreotide for the treatment of congenital hyperinsulinism: a prospective, open-label clinical trial and an observational study in Japan using a nationwide registry.

Octreotide, a long-acting somatostatin analog, has been used for treating hypoglycemia caused by congenital hyperinsulinism (CHI). However, octreotide has not been evaluated in clinical trials and has not been approved in any developed country. We aimed to test the efficacy and safety of octreotide for diazoxide-unresponsive CHI through a combination of a single-arm, open-label clinical trial (SCORCH study) and an observational study to collect data on the clinical course of patients treated off-label in Japan (SCORCH registry). In the SCORCH study, 5 patients were stabilized (blood glucose > 45 mg/dL) by hypertonic glucose infusion, and treated by continuous subcutaneous octreotide infusion at a dose of 5-25 µg/kg/day. Continuous blood glucose monitoring was performed between -24 and +48 hours. In 3 patients, a clinically meaningful rise in blood glucose was achieved and therapy was continued. The glucose infusion was gradually decreased and stopped after 5, 11, and 174 days, respectively. In one case, remission of CHI was reached after 606 days and octreotide was discontinued. The SCORCH registry included 19 diazoxide-unresponsive patients treated by subcutaneous octreotide, by continuous infusion or multiple daily injections. Of the 17 patients treated with hypertonic glucose infusion, the infusion rate was reduced after 4 weeks to less than 50% in 11 patients (64.7%) and stopped in 9 (52.9%). During the combined observation period of 695.4 patient-months in both studies, no severe adverse events related to octreotide were observed. In conclusion, subcutaneous octreotide injection was effective and well tolerated in the majority of patients with diazoxide-unresponsive CHI.

Does intensity-modulated radiation therapy (IMRT) alter prostate size? Magnetic resonance imaging evaluation of patients undergoing IMRT alone.

AIM: To assess the changes in prostate size in patients with prostate cancer undergoing intensity-modulated radiation therapy (IMRT). BACKGROUND: The effect of size change produced by IMRT is not well known. MATERIALS AND METHODS: We enrolled 72 patients who received IMRT alone without androgen-deprivation therapy and underwent magnetic resonance imaging (MRI) examination before and after IMRT. The diameter of the entire prostate in the anterior-posterior (P-AP) and left-right (P-LR) directions was measured. The transitional zone diameter in the anterior-posterior (T-AP) and left-right (T-LR) directions was also measured. RESULTS: The average relative P-AP values at 3, 6, 12, 24, and 36 months after IMRT compared to the pre-IMRT value were 0.94, 0.90, 0.89, 0.89, and 0.90, respectively; the average relative P-LR values were 0.93, 0.92, 0.91, 0.91, and 0.90, respectively. The average P-AP and P-LR decreased by approximately 10% during the 12 months post-IMRT, and remained unchanged thereafter. The average relative T-AP values at 3, 6, 12, 24, and 36 months after IMRT compared to the pre-IMRT value were 0.93, 0.88, 0.91, 0.87, and 0.89, respectively; the average relative T-LR values were 0.96, 0.90, 0.91, 0.87, and 0.88, respectively. The average T-AP and T-LR also decreased by approximately 10% during the 12 months post-IMRT, and remained unchanged thereafter. At 12 months after IMRT, the average relative T-AP was significantly lower in patients with recurrence than in those without recurrence. CONCLUSIONS: The average prostate diameter decreased by approximately 10% during the 12 months after IMRT; thereafter remained unchanged.

18-F fluorodeoxyglucose uptake in positron emission tomography as a pathological grade predictor for renal clear cell carcinomas.

OBJECTIVES: To evaluate the usefulness of Fluorine-18 fluorodeoxyglucose positron emission tomography/computed tomography (18-F FDG-PET/CT) in the prediction of Fuhrman pathological grades of renal clear cell carcinoma (cRCC). METHODS: This retrospective study was approved by our institutional review board, and written informed consent was waived. Thirty-one patients with pathologically proven cRCC underwent 18-F FDG-PET/CT for tumour staging. Maximum standardized uptake value of cRCC (tumour SUVmax) and mean SUV of the liver and spleen (liver and spleen SUVmean) were measured by two independent observers. Tumour SUVmax, tumour-to-liver SUV ratio, and tumour-to-spleen SUV ratio were correlated with the pathological grades. RESULTS: Logistic analysis demonstrated that only the tumour-to-liver SUV ratio was a significant parameter for differentiating high-grade (Fuhrman grades 3 and 4) tumours from low-grade (Fuhrman grades 1 and 2) tumours (P = 0.007 and 0.010 for observers 1 and 2, respectively). Sensitivity, specificity, and positive and negative predictive values for detecting tumours of Fuhrman grades 3 and 4 were 64, 100, 100, and 77%, respectively, for observer 1, and 79, 88, 85, and 83%, respectively, for observer 2. CONCLUSIONS: The tumour-to-liver SUV ratio with 18-F FDG-PET/CT appeared to be a valuable imaging biomarker in the prediction of high-grade cRCC. KEY POINTS: • Tumour SUV max was correlated with the Fuhrman grades. • High-grade tumours have significantly higher SUV max than low-grade tumours. • Tumour-to-liver SUV ratio is useful in the prediction of high-grade cRCC.

Congenital hyperinsulinism: global and Japanese perspectives.

Over the past 20 years, there has been remarkable progress in the diagnosis and treatment of congenital hyperinsulinism (CHI). These advances have been supported by the understanding of the molecular mechanism and the development of diagnostic modalities to identify the focal form of ATP-sensitive potassium channel CHI. Many patients with diazoxide-unresponsive focal CHI have been cured by partial pancreatectomy without developing postsurgical diabetes mellitus. Important novel findings on the genetic basis of the other forms of CHI have also been obtained, and several novel medical treatments have been explored. However, the management of patients with CHI is still far from ideal. First, state-of-the-art treatment is not widely available worldwide. Second, it appears that the management strategy needs to be adjusted according to the patient's ethnic group. Third, optimal management of patients with the diazoxide-unresponsive, diffuse form of CHI is still insufficient and requires further improvement. In this review, we describe the current landscape of this disorder, discuss the racial disparity of CHI using Japanese patients as an example, and briefly note unanswered questions and unmet needs that should be addressed in the near future.

Efficacy and safety of long-term, continuous subcutaneous octreotide infusion for patients with different subtypes of KATP-channel hyperinsulinism.

OBJECTIVE: To evaluate the efficacy of long-term, continuous, subcutaneous octreotide infusion for congenital hyperinsulinism caused by mutations in the KATP-channel genes, KCNJ11 and ABCC8. PATIENTS: Fifteen Japanese patients with diazoxide-unresponsive, KATP-channel hyperinsulinism. METHODS: Molecular diagnoses were made by sequencing and multiple ligation-dependent probe amplification analysis. In patients with paternally inherited, monoallelic mutations, 18F-DOPA PET scans were performed to determine the location of the lesion. The patients were treated with continuous, subcutaneous octreotide infusion at a dosage of up to 25 µg/kg/day, using an insulin pump to maintain blood glucose levels higher than 3.33 mmol/l. Additional treatments (IV glucose, glucagon or enteral feeding) were administered as needed. The efficacy of the treatment was assessed in patients who received octreotide for 4 months to 5.9 years. RESULTS: Three patients had biallelic mutations, and 12 had monoallelic, paternally inherited mutations. Four patients with monoallelic mutations showed diffuse 18F-DOPA uptake, whereas seven patients showed focal uptake. Octreotide was effective in all the patients. The patients with biallelic mutations required a higher dosage (17-25 µg/kg/day), and two patients required additional treatments. By contrast, the patients with monoallelic mutations required a lower dosage (0.5-21 µg/kg/day) irrespective of the PET results and mostly without additional treatments. Treatment was discontinued in three patients at 2.5, 3.3 and 5.9 years of age, without psychomotor delay. Except for growth deceleration at a higher dosage, no significant adverse effects were noted. CONCLUSIONS: Long-term, continuous, subcutaneous octreotide infusion is a feasible alternative to surgery especially for patients with monoallelic KATP-channel mutations.

Is "black geode" sign a characteristic MRI finding for extracranial schwannomas?

PURPOSE: To evaluate whether the "black geode" sign is a characteristic magnetic resonance imaging (MRI) finding for extracranial schwannomas. MATERIALS AND METHODS: Forty-three patients with pathologically confirmed extracranial schwannomas underwent preoperative gadolinium-enhanced MRI. The black geode sign was defined as the appearance of enhanced outer and inner rings. MR images were retrospectively reviewed for size, configuration, and signal intensity of the lesions in addition to the presence of the black geode sign. RESULTS: Gadolinium-enhanced T1-weighted images revealed the black geode sign in seven of 43 patients (16%). The thickness of inner rings (mean 0.6 cm, range 0.3-0.8 cm) was significantly greater than that of outer rings (mean 0.2 cm, range 0.1-0.3 cm) (P < 0.01). While outer rings were circular or elliptical in shape with smooth contours, inner rings had a lobular configuration with irregular thickness and contours. The degrees of enhancement were significantly stronger with inner rings than with outer rings (P < 0.01). In histopathological correlation of five patients who underwent total excision, inner and outer rings corresponded to peridegenerative areas and fibrous capsules, respectively. CONCLUSION: The black geode sign may be fairly specific to extracranial schwannomas on gadolinium-enhanced MR images.

Congenital hyperinsulinism in an infant with paternal uniparental disomy on chromosome 11p15: few clinical features suggestive of Beckwith-Wiedemann syndrome.

Beckwith-Wiedemann syndrome (BWS) is the most common congenital overgrowth syndrome involving tumor predisposition. BWS is caused by various epigenetic or genetic alterations that disrupt the imprinted genes on chromosome 11p15.5 and the clinical findings of BWS are highly variable. Hyperinsulinemic hypoglycemia is reported in about half of all babies with BWS. We identified an infant with diazoxide-unresponsive congenital hyperinsulinism (HI) without any apparent clinical features suggestive of BWS, but diagnosed BWS by molecular testing. The patient developed severe hyperinsulinemic hypoglycemia within a few hours after birth, with macrosomia and mild hydronephrosis. We excluded mutations in the K(ATP) channel genes on chromosome 11p15.1, but found a rare homozygous single nucleotide polymorphism (SNP) of ABCC8. Parental SNP pattern suggested paternal uniparetal disomy in this region. By microsatellite marker analysis on chromosome 11p15, we could diagnose BWS due to the mosaic of paternal uniparental disomy. Our case suggests that some HI of unknown genetic etiology could involve undiagnosed BWS with no apparent clinical features, which might be diagnosed only by molecular testing.

CT of the pancreas: comparison of anatomic structure depiction, image quality, and radiation exposure between 320-detector volumetric images and 64-detector helical images.

PURPOSE: To prospectively compare 320-detector volumetric and 64-detector helical computed tomographic (CT) images of the pancreas for depiction of anatomic structures, image noise, and radiation exposure. MATERIALS AND METHODS: This study was approved by the institutional review board, and written informed consent was obtained. A total of 154 patients (85 men, 69 women; age range, 26-85 years; mean age, 67 years) who underwent biphasic (arterial and pancreatic phase) contrast material-enhanced CT performed with a 320-detector scanner were randomized into two groups: the 320-detector group and the 64-detector group. Biphasic transaxial multiplanar reformatted images and volume-rendered CT angiograms were obtained. CT numbers in the abdominal aorta, pancreas, and abdominal wall fat tissue; signal-to-noise ratio (SNR); and dose-length product (DLP) were compared. In addition, image quality and focal lesion depiction (n = 35) were qualitatively determined in the two groups. Unpaired t and Mann-Whitney tests were used for quantitative and qualitative assessment, respectively. RESULTS: No significant difference in CT numbers of the abdominal aorta and pancreas was noted between the two groups. Mean DLP was 43% lower in the 320-detector group (675.4 mGy·cm) than in the 64-detector group (1187.8 mGy·cm) (P < .001). SNR of the abdominal aorta, pancreas, and abdominal wall fat on biphasic images was significantly lower in the 320-detector group than in the 64-detector group (P < .001). Image quality was acceptable in both groups and was slightly better in the 64-detector group for pancreatic phase axial images (P = .02) and arterial phase multiplanar reformatted images (P < .01). No significant difference was found in the depiction of pancreatic parenchyma, main pancreatic duct, focal pancreatic lesions, splanchnic arteries, or most of the small splanchnic arterial branches. CONCLUSION: A 320-detector CT scan facilitates fast volumetric contrast-enhanced CT of the entire pancreas with acceptable image quality, even though SNR was significantly lower at 320-detector volumetric scanning.

Diagnostic accuracy of [¹8F]-fluoro-L-dihydroxyphenylalanine positron emission tomography scan for persistent congenital hyperinsulinism in Japan.

OBJECTIVE: We aimed to elucidate the accuracy and limitations of [(18)F]-fluoro-L-dihydroxyphenylalanine ([(18) F]DOPA) positron emission tomography (PET) for Japanese patients with congenital hyperinsulinism. Although [(18)F]DOPA PET is reported to be useful for precisely localizing the focal form of congenital hyperinsulinism, previous reports are mostly from European and North American centres. PATIENTS: Seventeen Japanese infants with congenital hyperinsulinism. MEASUREMENTS: [(18)F]DOPA PET studies were carried out, and the results were assessed by simple inspection or by a quantitative measurement termed the 'Pancreas Percentage', which expresses the uptake of the head, body or tail of the pancreas as a percentage of the total maximum standardized uptake value of the whole pancreas. The results were compared with those of other studies, including genetic analysis and histology. RESULTS: By simple inspection, when a single focal uptake was obtained, the localization and histology were correct in all cases that underwent pancreatectomy. However, the overall results were consistent with the molecular diagnosis and histology in only 7/17 and 6/12 patients, respectively. The inaccuracy of PET studies by inspection was because of elevated background uptake that mimicked a diffuse or multifocal appearance. The accuracy improved substantially using the Pancreas Percentage; it was consistent with the molecular diagnosis and histology in 10/17 and 9/12 patients, respectively. CONCLUSIONS: In contrast to the results of previous reports, [(18)F]DOPA PET appears to be less efficient for diagnosing Japanese patients with congenital hyperinsulinism. However, the diagnostic accuracy is substantially improved when this technique is combined with the Pancreas Percentage.

T2*-weighted MR imaging findings of giant cell tumors of bone: radiological-pathological correlation.

PURPOSE: To assess the correlation between T2*-weighted MR imaging and pathological findings of giant cell tumors (GCT) of bone. METHODS: Of the 33 patients with histopathologically proven GCT of bone, 12 were examined using 1.5-T MR imaging, including T2*-weighted imaging, and were included in this study. The imaging and pathological findings of GCTs were compared between GCTs with and without hypointensity on T2*-weighted images (T2* hypointensity). RESULTS: T2* hypointensity was observed in 6 out of 12 (50%) GCTs. Septal formation (83% vs. 17%; p < 0.05) and cystic formation (67% vs. 0%; p < 0.05) on T2-weighted images was significantly more frequent in the GCTs with T2* hypointensity compared with those without T2* hypointensity. Among the six GCTs with T2* hypointensity, a large amount of hemosiderin deposition was pathologically observed in five (83%) cases, whereas small amounts of hemosiderin deposition was seen in one (17%) case. In contrast, among the six GCTs without T2* hypointensity, a small amount of hemosiderin deposition was pathologically observed in all six (100%). CONCLUSION: Half of the GCTs showed T2* hypointensity, which is characteristic of hemosiderin deposition; whereas, the other half did not show T2* hypointensity due to a small amount of hemosiderin deposition.

The feasibility of dedicated breast PET for the assessment of residual tumor after neoadjuvant chemotherapy.

PURPOSE: To evaluate the utility of ring-type dedicated breast positron emission tomography (dbPET) for the detection of the residual tumor after neoadjuvant chemotherapy (NAC). MATERIALS AND METHODS: This prospective study included 27 women with histologically proven breast cancer over a 37-month period. All patients underwent ring-type dbPET followed by whole-body PET-CT (WBPET) for preoperative tumor evaluation and re-staging after NAC. The maximum standardized uptake value (SUVmax) of the tumor lesion and the degree of confidence for the presence of the residual tumor were compared between pathological complete response (pCR) and non-pCR tumors. The sensitivity, specificity, and area under the receiver operating characteristic curve (AUC) for the detection of a non-pCR tumor were compared between dbPET and WBPET. RESULTS: On dbPET, SUVmax was significantly higher in non-pCR than in pCR tumors (P = 0.030). The sensitivity for the detection of a non-pCR tumor was significantly higher with dbPET than with WBPET (84.2% vs 26.3%, P = 0.001). In the qualitative analysis, the sensitivity for the detection of a non-pCR tumor was also significantly higher with dbPET than with WBPET (57.9% vs 21.1%, P = 0.016). CONCLUSION: The dbPET can provide more sensitive detection of residual tumor after NAC than can WBPET.

Evaluation of organ involvement in intravascular large B-cell lymphoma by 18F-fluorodeoxyglucose positron emission tomography.

To evaluate the role of 18F-fluorodeoxyglucose positron emission tomography (FDG-PET) in intravascular large B-cell lymphoma (IVLBCL), we retrospectively analyzed four consecutive IVLBCL patients receiving FDG-PET before treatment between May 2006 and November 2007. Patients were two men and two women (median age 62 years, range 54-76 years). All patients received bone marrow biopsies and random skin biopsies and two of the four patients underwent renal biopsy for diagnosis. Accuracy of FDG-PET for the detection of organ involvements was analyzed by comparing results of pathological findings. Concordant results with respect to bone marrow involvement were accurately obtained for two patients. Skin and renal involvements were undetectable by FDG-PET regardless of positive pathological findings. One patient with a false-negative FDG-PET result showed fewer lymphoma cells in the bone marrow specimen than patients with concordant FDG-PET results. These results suggest false-negative results for some types of organ involvement. Careful interpretation of the results of FDG-PET in IVLBCL is thus required.

Multi-detector row CT of the kidney: optimizing scan delays for bolus tracking techniques of arterial, corticomedullary, and nephrographic phases.

PURPOSE: To determine optimal scan delays for renal arterial-, corticomedullary-, and nephrographic-phase imaging with multi-detector row computed tomography (MDCT) of the kidney using a bolus-tracking technique. METHODS AND MATERIALS: One hundred and twenty-eight patients underwent three-phase CT scan of the kidney with eight-row MDCT after receiving 2 mL/kg of 300 mgI/mL contrast medium at 4 mL/s. Patients were prospectively randomized into three groups with different scan delays for the three scan phases (arterial, corticomedullary, and nephrographic) after bolus-tracking triggered at 50 HU of aortic contrast enhancement: group 1 (5, 20, 45 s); group 2 (10, 25, 50s); and group 3 (15, 30, 55 s). Mean CT values (HU) of the abdominal aorta, renal artery, renal vein, renal cortex, and renal medulla were measured; increases in CT values pre- to post-contrast were assessed as contrast enhancement. Renal artery-to-vein and renal cortex-to-medulla contrast differences were also assessed. Qualitative analysis was also performed. RESULTS: Mean renal artery enhancement was 240-288 HU at 5-15s after the trigger and peaked at 10s (P<.001). Mean renal cortical enhancement was 195-217 HU at 10-30s and peaked at 25s (P<.01). Contrast enhancement in the renal medulla increased gradually and reached mean 145 HU at 55 s. Cortex-to-medulla contrast difference was high (110-140 HU) at 5-30s and decreased below 30 HU at 45 s after the trigger. Renal artery-to-vein contrast difference was high (121-125 HU) at 5-10s. Qualitative results correlated well with quantitative results. CONCLUSION: For the injection protocol used in this study, optimal scan delays after the bolus-tracking trigger were 5-10 s for renal arterial, 15-25 s for corticomedullary, and 50-55 s for nephrographic phases.

Utility of 111In-Cl3 scintigraphy for differentiating bone marrow reconversion.

Indium chloride (111In-Cl3) scintigraphy has been used to evaluate various hematological diseases for many years. However, there have been few reports on patients with bone marrow reconversion showing high uptake in 111In-Cl3 scintigraphy. Herein, we report a case of a 68-year-old man with esophageal cancer who underwent 18F-FDG PET/CT for staging of the disease. 18F-FDG PET/CT demonstrated high uptake in the first lumbar vertebral body, which was difficult to distinguish bone metastasis and bone marrow reconversion. 111In-Cl3 scintigraphy demonstrated specific findings with high uptake in the lesion, indicating bone marrow hyperplasia or reconversion.

MDCT of the liver and hypervascular hepatocellular carcinomas: optimizing scan delays for bolus-tracking techniques of hepatic arterial and portal venous phases.

OBJECTIVE: The purpose of our study was to determine the optimal scan delays required for hepatic arterial and portal venous phase imaging and for the detection of hypervascular hepatocellular carcinomas (HCCs) in contrast-enhanced MDCT of the liver using a bolus-tracking program. SUBJECTS AND METHODS: CT images (2.5-mm collimation, 5-mm thickness with no intersectional gap) detected an increase in the CT value of 50 H in the lower thoracic aorta. The images were obtained after an IV bolus injection of 2 mL/kg of nonionic iodine contrast material (300 mg I/mL) at 4 mL/s in 171 patients, who were prospectively randomized into three groups with scans commencing at 5, 20, and 45 seconds; 10, 25, and 50 seconds; and 15, 30, and 55 seconds for the first (acquisition time: 4.3 seconds), second (4.3 seconds), and third (9.1 seconds) phases, respectively, after a bolus-tracking program. CT values of the aorta, spleen, proximal portal veins, liver parenchyma, and hepatic veins were measured. Increases in CT values from unenhanced to contrast-enhanced CT were assessed using a contrast enhancement index (CEI). Spleen-to-liver and HCC-to-liver contrasts were also assessed. A qualitative degree of contrast enhancement in each organ was prospectively assessed by two independent radiologists. RESULTS: At 10-15 seconds, the CEI of the aorta reached 300-336 H and that of the spleen reached 97-108 H without significant enhancement of liver parenchyma (15-25 H). The CEI of the proximal portal veins moderately increased (75-104 H) at 10-15 seconds, but no significant enhancement of hepatic veins was observed (24-51 H). The CEI of liver parenchyma peaked (59-63 H) at 45-55 seconds, when the CEIs of the aorta (117-125 H) and spleen (73-82 H) decreased. Spleen-to-liver contrast (81-84 H) was highest at 10-20 seconds and HCC-to-liver contrast (39-44 H) was highest at 10-15 seconds. The qualitative results correlated well with quantitative results. CONCLUSION: The optimal scan delays for hepatic arterial and portal venous phases after the bolus-tracking program detected threshold enhancement by 50 H in the lower thoracic aorta for the detection of hypervascular HCCs were 10-15 and 45-55 seconds, respectively.

Solitary mediastinal lymph node metastasis of hepatocellular carcinoma: MR imaging findings.

A 65-year-old man with multiple hepatocellular carcinomas in the liver with type C viral hepatitis had a solitary mediastinal lymph node metastasis in the right paratracheal to tracheobronchial region. Surgical resection for the mediastinal metastasis was undertaken based on magnetic resonance (MR) imaging findings, suggesting its radicality. We assess the MR imaging findings and presumable pathways of lymphatic metastasis from the liver to mediastinal lymph nodes in this report.

Intraosseous schwannoma of the ilium.

We presented a 27-year-old male diagnosed with intraosseous schwannoma of the ilium. Computed tomographic images revealed a well-demarcated, lobulated, expansile, osteolytic lesion in the right supraacetabular region of the ilium. In addition, an intratumoral punctate calcification and a sclerotic rim were observed. T2-weighted magnetic resonance (MR) images demonstrated a heterogeneously hyperintense lesion with a hypointense rim. Major parts of the lesion, excluding some central areas, were enhanced on gadolinium-enhanced MR images. Pathological examination revealed an intraosseous schwannoma. Our findings indicate that intraosseous schwannoma should be considered when images demonstrate a well-demarcated, lobulated, expansile, osteolytic lesion with a sclerotic rim.

Focal form of congenital hyperinsulinism clearly detectable by contrast-enhanced computed tomography imaging.

The focal form of congenital hyperinsulinism (CHI) is characterized by a cluster of abnormal insulin-oversecreting ß cells within a restricted area of the pancreas. Although identification of the focal lesion is very important in the management of CHI, it has been reported that imaging studies, including computed tomography (CT), magnetic resonance imaging (MRI) scans, or angiography, are not helpful in identifying the focal lesion. Currently, fluorine-18-L-dihydroxyphenylalanine positron emission tomography ((18)F-DOPA PET) is believed to be the only imaging modality that can identify the focal lesions. In this report, however, we present a case of a 7-month-old girl with the focal form of CHI, caused by a loss-of-function mutation in the ABCC8 gene, whose lesion was clearly visible as a hyperenhancing nodule on contrast-enhanced CT and dynamic MRI imaging.