MR imaging features of uterine adenomyomas

Background

To evaluate the magnetic resonance (MR) imaging features of uterine adenomyoma in comparison with histopathologic findings.

Materials and methods

MR images of seven patients who had surgically proven uterine adenomyoma were retrospectively reviewed by two radiologists in consensus regarding the morphologic appearance, including tumor size, location, margin, presence of concomitant adenomyosis, presence and signal intensity of cavity within tumor, and signal intensity and enhancement pattern of solid portion of tumor. MR imaging findings were correlated with histopathologic findings.

Results

Tumor location was submucosal in three cases, subserosal in two, and mixed mural/subserosal in two. All tumors were well circumscribed on T2-weighted images and contrast-enhanced fat-suppressed T1-weighted images. In six cases, well defined cavities of high signal intensity, which reflected hemorrhagic cavities pathologically, were demonstrated within the tumors on T1-weighted images. Concomitant adenomyosis was observed in five cases. Solid portion of all tumors except hemorrhagic cavities exhibited iso-signal intensity on T1-weighted images, various signal intensity on T2-weighted images, and homogeneous enhancement on contrast-enhanced fat-suppressed T1-weighted images in five cases.

Conclusion

When MR imaging shows a well circumscribed mass with hemorrhagic cavities of high signal intensity on T1-weighted images and concomitant adenomyosis in the uterus, adenomyoma should be considered in the differential diagnosis.     

Primary hepatic neuroendocrine carcinoma: MR imaging findings including preliminary observation on diffusion-weighted imaging

Purpose

To investigate MR imaging findings of primary hepatic neuroendocrine carcinoma (PHNEC) including preliminary observations on diffusion-weighted imaging (DWI).

Materials and methods

MR images of eight patients with pathologically confirmed PHNEC were retrospectively analyzed. The morphological characteristics and dynamic enhancement patterns were evaluated.

Results

One case showed a well-defined solitary nodule with homogenous hypointensity on T1-weighted imaging (T1WI) and hyperintensity on T2-weighted imaging (T2WI) and DWI. The remaining seven cases appeared as well-defined dominant masses with multiple satellite nodules. The dominant masses demonstrated heterogeneous hypointensity on T1WI and hyperintensity on T2WI, which all appeared as a marked enhancement at arterial phase and rapid washout at portal venous phase. Six cases demonstrated rim-like enhancement at equilibrium phase. The satellite lesions showed heterogeneous hypointensity on T1WI and marked hyperintensity on T2WI with variable enhancements, such as homogeneous, rim-like enhancement. All the dominant masses and satellite nodules appeared as markedly hyperintensity and reduced apparent coefficient (ADCs) values on DWI. The mean ADC value of the tumors was significantly lower than that of surrounding liver parenchyma (1.02 ± 0.57 vs. 2.24 × 10^?3 mm²/s, p = 0.000).

Conclusion

PHNECs typically appear as a large dominant hypervascular mass accompanied by satellite nodules, with rapid washout and capsular enhancement on dynamic MR imaging and restricted diffusion on DWI.     

Evidence of diagnostic enhancement pattern in hepatocellular carcinoma nodules ≤2 cm according to the AASLD/EASL revised criteria

Purpose

To define the percentage of small (≤2 cm) hepatocellular carcinoma (HCC) nodules showing the diagnostic enhancement pattern at CEUS, computed tomography (CT), and gadobenate dimeglumine (Gd-BOPTA)—enhanced magnetic resonance (MR) imaging.

Methods

42 cirrhotic patients (26 male, 16 female; 67 ± 12 years) with 46 biopsy-proven HCCs ≤2 cm were included. Each HCC was scanned by CEUS, contrast-enhanced CT, and Gd-BOPTA-enhanced MR imaging. Nodule enhancement was evaluated by two readers. Independent analysis was followed by consensual analysis and the proportion of HCCs with the diagnostic enhancement pattern (nodule hyperenhancing on hepatic arterial phase and hypoenhancing on portal venous—late phase) on CEUS, CT, and MR imaging was compared by chi-square test.

Results

Very good inter-reader agreement was observed on hepatic arterial phase and portal venous—late phase: CEUS, k = 0.89 and 0.85; CT, k = 0.91 and 0.88; MR imaging, k = 0.96 and 0.94. CEUS and CT did not differ in the percentage of HCC nodules with a diagnostic enhancement pattern (18/46 and 16/46; P = 0.66), while MR imaging revealed the diagnostic pattern in higher percentage of nodules (29/46; P = 0.012) in comparison to CEUS and CT.

Conclusions

CEUS and contrast-enhanced CT did not differ in the percentage of small HCC nodules with diagnostic enhancement pattern, while Gd-BOPTA-enhanced MR imaging revealed the diagnostic pattern in a higher nodule number in comparison to CEUS and CT.     

Ovarian mucinous cystadenoma coexisting with benign Brenner tumor: MR imaging findings

Purpose

The purpose of this study was to describe the MR imaging findings of ovarian mucinous cystadenomas coexisting with benign Brenner tumors.

Materials and methods

MR images with a 1.5-T unit obtained in five consecutive patients (age range, 51–72 years; mean age, 61 years) with surgically confirmed ovarian mucinous cystadenomas coexisting with benign Brenner tumors were retrospectively reviewed for the presence, configuration, and signal intensity of cystic and solid components of the lesions.

Results

Tumors ranged in size from 7.5 to 22.1 cm (mean, 13.5 cm). In four patients (80%), the size of mucinous cystadenoma (range 6.4–22.1 cm; mean, 12.5 cm) was larger than that of Brenner tumor (range 0.2–9.1 cm; mean, 2.8 cm). All patients (100%) had cystic, and three (60%) had solid components. Four patients (80%) showed multilocular cystic, and one (20%) showed unilocular cystic appearance. MR imaging findings were classified into three patterns: (1) a bulky solid mass adjacent to the cystic component, (2) a mural nodule at the periphery of the cystic component, and (3) a cystic component without a detectable solid component. All four multilocular cystic areas exhibited “stained glass” appearances on both T1- and T2-weighted images, and all three solid areas showed homogeneous hypointensity on T2-weighted images.

Conclusion

Mucinous cystadenomas were often larger than the coexisting benign Brenner tumors. Mucinous cystadenomas coexisting with benign Brenner tumors should be considered when multilocular or unilocular cystic components are accompanied by homogeneously hypointense solid components on T2-weighted images.     

Rectal cancer in inflammatory bowel diseases: MR imaging findings

Purpose

To retrospectively analyze the MR imaging features of rectal cancer in patients with inflammatory bowel diseases (IBD).

Materials and methods

The MR imaging examinations of 13 patients with IBD-related rectal cancer were retrospectively reviewed. MR imaging included T2-weighted, diffusion-weighted (DW), and gadolinium chelate-enhanced MR imaging. MR imaging findings were analyzed and compared with endoscopic and histopathological findings.

Results

Eight patients (8/13; 62%) had active IBD and five (5/13; 38%) had quiescent IBD on MR imaging. Two different tumor patterns were individualized including clearly visible soft-tissue mass (4/13; 31%) (Type 1 tumor) and marked circumferential rectal wall thickening (9/13; 69%) (Type 2 tumor). Twelve tumors (12/13; 92%) showed high signal intensity on T2-weighted MR images. All six tumors studied with DW-MR imaging (6/6; 100%) showed high signal on DW-MR imaging with restricted diffusion on apparent diffusion coefficient (ADC) map. On gadolinium chelate-enhanced MR imaging, heterogeneous enhancement was observed in one tumor (1/13; 8%), whereas 12 tumors (12/13; 92%) showed homogeneous enhancement. MR imaging showed pelvic fistula and intrapelvic abscess in association with four (4/13; 31%) and two tumors (2/13; 15%), respectively.

Conclusion

Our limited retrospective study demonstrates that rectal cancer in IBD patients can present as a circumferential wall thickening resembling inflammation and can occur in the absence of fistula or abscess. The use of T2-weighted and DW-MR imaging is recommended to improve rectal cancer detection in patients with long-standing IBD.     

Hepatic angiosarcoma: cross-sectional imaging findings in seven patients with emphasis on dynamic contrast-enhanced and diffusion-weighted MRI

Objective

Primary hepatic angiosarcoma is a very rare and aggressive malignancy of vascular origin. We describe cross-sectional imaging findings of this entity with emphasis on dynamic contrast-enhanced (DCE) and diffusion-weighted (DWI) MR imaging.

Methods

Seven cases of pathologically confirmed hepatic angiosarcoma were retrospectively reviewed (CT and MRI examinations were available in seven and six patients, respectively). Two radiologists evaluated lesion growth patterns, attenuation, signal intensity characteristics, contrast enhancement patterns, and apparent diffusion coefficients (ADCs).

Results

Multifocal hepatic disease was present in six patients by means of a mixed pattern of large dominant masses and multiple small nodules; one patient had a solitary large mass. Unenhanced images depicted hemorrhagic areas and a markedly heterogeneous internal architecture within large tumors. Contrast-enhanced early phase images showed variable patterns including patchy peripheral or bizarre shaped intralesional foci of enhancement, peripheral rim enhancement, and small lesions without enhancement. On DCE images, the majority of lesions presented with varying degrees of progressive enhancement. Small nodules frequently displayed homogeneous enhancement on delayed phase images due to complete fill-in. DWI revealed a high interlesional variability of ADC values (range 0.57–2.41 × 10^?3 mm²/s, mean 1.37 × 10^?3 mm²/s).

Conclusion

Cross-sectional imaging findings of hepatic angiosarcoma reflect the varied histopathological composition of the tumors. Multifocal disease, hemorrhage within large lesions, as well as progressive enhancement on DCE images are typical features of hepatic angiosarcoma. The mean ADC of lesions was found to be slightly elevated in comparison with other hepatic malignancies.

     

Imaging Tumor Growth Non-invasively Using Expression of MagA or Modified Ferritin Subunits to Augment Intracellular Contrast for Repetitive MRI

Purpose

The bacterial gene MagA imparts magnetic properties to mammalian cells and provides a basis for cell tracking by magnetic resonance imaging (MRI). In a mouse model of tumor growth from transplanted cells, we used repetitive MRI to demonstrate the in vivo imaging potential of MagA expression relative to a modified ferritin overexpression system, lacking regulation through iron response elements (HF?+?LF).

Procedures

Subcutaneous tumor xenografts were monitored weekly from days 2 to 34 post-injection. Small animal MRI employed balanced steady-state free precession. Imaging was correlated with tumor histology using hematoxylin, Prussian Blue, Ki-67, and BS-1 lectin.

Results

Tumor heterogeneity with respect to tissue morphology and magnetic resonance (MR) contrast was apparent within a week of cell transplantation. In MagA- and HF?+?LF-expressing tumors, MR contrast enhancement was recorded up to day 20 post-injection and 0.073-cm³ tumor volumes. MagA-expressing tumors showed increases in both quantity and quality of MR contrast as measured by fractional void volume and contrast-to-noise ratio, respectively. MR contrast in both MagA- and HF?+?LF-expressing tumors was maximal by day 13, doubling fractional void volume 1 week ahead of controls.

Conclusions

MagA- and HF?+?LF-expressing tumor xenografts augment MR contrast after 1 week of growth. MagA expression increases MR contrast within days of cell transplantation and provides MR contrast comparable to HF?+?LF. MagA has utility for monitoring cell growth and differentiation, with potential for in vivo detection of reporter gene expression using MRI.     

CT findings of primary clear cell carcinoma of liver: with analysis of 19 cases and review of the literature

Purpose

To analyze CT characteristics of primary clear cell carcinoma of the liver (PCCCL) and improve the current understanding and diagnose accuracy of the tumor.

Methods

Pre- and post-contrast CT images of 19 patients with pathology proven PCCCL were retrospectively analyzed. The clinical data and CT findings as well as relevant literature reports were reviewed.

Results

Thirteen patients were tested positive for HBsAg, and two patients were positive for HCVAb. The serum alpha-fetoprotein (AFP) levels of most tumors (14/19) were ≤20 ng/ml with 14 cases were associated with liver cirrhosis. All lesions were solitary intraparenchymal mass lesions which have well-defined boarders. On pre-contrast CT scans, 15 lesions appeared as hypo-attenuation and four lesions appeared as isointensity to the adjacent liver parenchyma. On post-contrast CT scans, 16 lesions showed avid enhancement on the hepatic arterial phase, of which 6 lesions were hypo-attenuation, and 10 lesions remained slightly hyper-attenuation or iso-attenuation on the portal venous phase images. Three lesions showed only mild enhancement on the hepatic arterial phase and hypo-attenuation on the portal venous phase. All lesions demonstrated hypointensity on the equilibrium phase. There are 12 lesions showed pseudocapsules. None of patients showed signs of portal vein thrombosis. There was no distal metastasis except only one patient had lymph node metastasis.

Conclusion

The characteristics of CT imaging of PCCCL, such as tend to form pseudocapsules and less involved with vascular invasion, could be useful in differentiating from common type hepatocellular carcinoma (CHCC). Some CT imaging characteristics of PCCCL are similar to CHCC, such as prone to occur in patients with liver cirrhosis and early enhancement pattern on the hepatic arterial phase as well as hypo-attenuation on the equilibrium phase. Those features could be useful in differentiating PCCCL from other liver tumors, such as hemangioma and hepatic metastases.     

CT and MR features of struma ovarii

Objective

The purpose of this study is to investigate radiologic findings of struma ovarii, and to correlate both CT and MR findings.

Materials and methods

MR images of 26 cases were retrospectively reviewed. Post-contrast enhanced T1-weighted images were available in 17 patients. CT images, including seven non-contrast and eleven post-contrast studies, were available for review in 13 cases.

Results

All 26 tumors appeared as well-defined cystic tumors with solid components, which were multilobulated surfaces in 19 and smooth surfaces in seven. Twenty-four was multicystic, whereas two were unilocular. The solid components were recognized as thickened septi or walls in 23 and a mass in three tumors. On T2-weighted images, loculi of prominent low intensity were recognized in 16 tumors. On T1-weighted images, the punctuate foci of high intensity were recognized in 24 tumors in or adjacent to the solid components. Ascites was present in only one lesion. In six of seven cases with non-contrast CT images, high attenuation areas were recognized. In five of these six tumors, high attenuation areas corresponded to the areas of prominent low intensity and the solid components on T2-weighted images. In seven cases with CT, curvilinear calcifications were recognized in the solid components.

Conclusion

Struma ovarii typically presents as a lobulated multicystic lesion with solid components. The tumors frequently include loculi of low intensity on T2-weighted images and punctuate foci of high intensity on T1-weighted images. On CT, high attenuation areas and calcifications in the solid components are common findings.     

Cardiac volumetry in patients with heart failure and reduced ejection fraction: a comparative study correlating multi-slice computed tomography and magnetic resonance tomography. Reasons for intermodal disagreement

Background

In humans with normal hearts multi-slice computed tomography (MSCT) based volumetry was shown to correlate well with the gold standard, cardiac magnetic resonance imaging (CMR). We correlated both techniques in patients with various degrees of heart failure and reduced ejection fraction (HFREF) resulting from cardiac dilatation.

Methods

Twenty-four patients with a left ventricular end-diastolic volume (LV-EDV) of ≥ 150 ml measured by angiography underwent MSCT and CMR scanning for left and right ventricular (LV, RV) volumetry. MSCT based short cardiac axis views were obtained beginning at the cardiac base advancing to the apex. These were reconstructed in 20 different time windows of the RR-interval (0–95%) serving for identification of enddiastole (ED) and end-systole (ES) and for planimetry. ED and ES volumes and the ejection fraction (EF) were calculated for LV and RV. MSCT based volumetry was compared with CMR.

Results

MSCT based LV volumetry significantly correlates with CMR as follows: LV-EDV r = 0.94, LV-ESV r = 0.98 and LV-EF r = 0.93, but significantly overestimates LV-EDV and LV-ESV and underestimates EF (P < 0.0001). MSCT based RV volumetry significantly correlates with CMR as follows: RV-EDV r = 0.79, RV-ESV r = 0.78 and RV-EF r = 0.73, but again significantly overestimates RV-EDV and RV-ESV and underestimates RV-EF (P < 0.0001).

Conclusion

When compared with CMR a continuous overestimation of volumes and underestimation of EF needs to be considered when applying MSCT in HFREF patients.     

MR imaging in the characterization of small renal masses

Objective

The aim of our study was to evaluate the effectiveness of MR imaging for the characterization of small (<2 cm) renal lesions described as indeterminate on prior US or CT

Materials and methods

Sixty-three small renal masses in 51 patients considered indeterminate on prior ultrasound or CT scans were included in the study. A retrospective evaluation of the examinations was performed independently by two body magnetic resonance imaging (MRI) radiologists who were unaware of the final diagnosis. A 3-point confidence scale (1: benign, 2: indeterminate, and 3: malignant) was established to determine the level of suspicion for malignancy. Interobserver agreement was determined with a weighted kappa statistic. The diagnosis was verified by imaging follow-up of at least 24 months (mean 60 months) in 53 lesions and by pathology in 10 lesions.

Results

MRI detected all eight malignancies in the series. There were eight malignant lesions and two benign lesions among those with pathologic follow-up. No interval growth or evidence of malignancy in the remaining 53 lesions was found for a minimum of 24 months by repeat imaging. The sensitivity, specificity, positive predictive value, and negative predictive value of MRI for differentiating benign from malignant small renal lesions were 100% (62.9–100%, 95% CI), 94.5% (84.9–98.8%, 95% CI), 72.7% (39.1–93.6%, 95% CI), and 100% (93.1–100%, 95% CI), respectively. The kappa value for interobserver agreement was 0.77 (95% CI 0.59–0.96, p-value <0.001).

Conclusion

MR imaging is an effective method for characterizing small (<2 cm) renal masses found to be indeterminate by US or CT.     

CT imaging characteristics of oncocytic adrenal neoplasms (OANs): comparison with adrenocortical carcinomas

Objective

Oncocytic adrenal neoplasms (OANs) are rare, but are an important subtype of adrenal tumors that is being diagnosed with increasing frequency. Unfortunately, the imaging characteristics of this tumor have not been well described. Our purpose was to identify CT features to differentiate OANs from adrenocortical carcinomas (ACC).

Materials and methods

From 1991 to 2012, 18 patients with OANs were identified from our institution’s pathology database. Twelve had CT examinations available for review. CT characteristics of five benign and seven malignant OANs were reviewed by two abdominal radiologists, and compared to ACC (n = 10). Morphologic characteristics and density measurements were recorded for each imaging phase. Absolute contrast washout was calculated and compared.

Results

Benign OANs were smaller [mean size 3.7 cm (range 2.6–5.3)] and more homogeneous than malignant OANs and demonstrated greater washout [mean washout percentage 72.3% (range 61–88)]. Malignant OANs demonstrated features similar to ACCs, including size [mean 9.4 cm (range 5.2–9.8)] and internal necrosis (n = 6). Mean enhancement washout percentage for malignant OANs was 12% (range ?8 to 32).

Conclusion

Benign OANs (oncocytomas) may be distinguished from lipid-rich adenomas on non-contrast CT but may be indistinguishable from lipid-poor adenomas. Malignant oncocytic neoplasms can demonstrate features similar to ACCs, including larger size, internal necrosis, and lower percentage enhancement washout.     

Usability of unbiased nonlocal means for de-noising intraoperative magnetic resonance images in neurosurgery

Purpose

   Intraoperative magnetic resonance imaging (iMRI) is a powerful tool that allows real-time image-guided excision of brain tumors. However, low magnetic field iMRI devices may produce low-quality images due to nonideal imaging conditions in the operating room and additional noise of unknown origin. The purpose of this study was to evaluate a three-dimensional unbiased nonlocal means filter for iMRI (UNLM-i) that we developed in order to enhance image quality and increase the diagnostic value of iMRI.

Methods

   We first evaluated the effect of UNLM by assessing the modulation transfer function (MTF) and Weiner spectrum (WS) of UNLM in simulated imaging. We then tested the diagnostic value of UNLM-i de-noising by applying it to a series of randomly chosen iMR images that were assessed by 4 neurosurgeons and 4 radiological technologists using a 5-point rating scale to compare 13 parameters, including tumor visibility, edema, and sulci, before and after de-noising.

Results

   Unbiased nonlocal means provided better MTF in comparison with other filters, and the WS for UNLM de-noising was reduced for all spatial frequencies. Postprocessing UNLM-i allowed de-noising with preserved edges and \(>\) twofold improvement in the signal-to-noise ratio without extending the MRI scanning time ( \(p < 0.001\) ). The diagnostic value of UNLM-i de-noising was rated as “superior” or “better” in \(>\) 80 % of cases in terms of contrast between white and gray matter and visibility of sulci, tumor, and edema ( \(p < 0.001\) ).

Conclusions

   Unbiased nonlocal means filter for iMRI de-noising proved very useful for image quality enhancement and assistance in the interpretation of iMR images.     

Protein-Based MRI Contrast Agents for Molecular Imaging of Prostate Cancer

Purpose

The purpose of this study was to demonstrate a novel protein-based magnetic resonance imaging (MRI) contrast agent that has the capability of targeting prostate cancer and which provides high-sensitivity MR imaging in tumor cells and mouse models.

Procedure

A fragment of gastrin-releasing peptide (GRP) was fused into a protein-based MRI contrast agent (ProCA1) at different regions. MR imaging was obtained in both tumor cells (PC3 and H441) and a tumor mouse model administrated with ProCA1.GRP.

Results

PC3 and DU145 cells treated with ProCA1.GRPs exhibited enhanced signal in MRI. Intratumoral injection of ProCA1.GRP in a PC3 tumor model displayed enhanced MRI signal. The contrast agent was retained in the PC3 tumor up to 48 h post-injection.

Conclusions

Protein-based MRI contrast agent with tumor targeting modality can specifically target GRPR-positive prostate cancer. Intratumoral injection of the ProCA1 agent in the prostate cancer mouse model verified the targeting capability of ProCA1.GRP and showed a prolonged retention time in tumors.     

Multi-modality imaging findings of splenic hamartoma: a report of nine cases and review of the literature

Purpose

To investigate the presentation of splenic hamartomas (SHs) on ultrasonography (US), CT and MRI.

Methods

Nine patients (5 males and 4 females, mean age, 52.8 years) with pathologically proven SHs were included in this study. US, CT and MRI images were analyzed retrospectively, and imaging features were correlated with pathological findings.

Results

SHs appeared solitary lesion (n = 8) and multiple lesions (n = 1) in the present study. (1) In 8 cases of solitary lesion, the lesions appeared as solid nodules or masses with well-defined margins and varying echogenicity (hyperecho = 5, hypoecho = 2, strong echo = 1) on ultrasound. The lesions showed iso-attenuation (n = 3) or slightly hypo-attenuation (n = 4) on unenhanced CT, and calcification were revealed in 3 lesions. MRI showed isointensity (n = 3) or hypointensity (n = 2) on the T1-weighted image, and heterogeneous hypointensity (n = 2), slightly hyperintensity (n = 2) and hyperintensity (n = 1) on the T2-weighted image. The enhanced patterns of SHs showed mild diffuse heterogeneous enhancement (n = 6) and prominent enhancement (n = 1) during arterial phase and above 7 lesions were demonstrated progressive enhancement at delayed phase on enhanced CT. One lesion without any enhancement was revealed in another patient. (2) One case of multiple lesions included 1 cystic lesion with irregular calcification and 7 solid lesions with progressive enhancement on CT images.

Conclusions

Combination of a variety of imaging modalities could more fully reflect the pathological characteristics and contribute to the diagnosis of SH.     

Intrahepatic cholangiocarcinoma: relationship between tumor imaging enhancement by measuring attenuation and clinicopathologic characteristics

Purpose

Arterial enhancement of intrahepatic cholangiocarcinoma (ICC) has been noted. To precisely identify the characteristics of tumor enhancement patterns, we examined the relationship between CT attenuation in the tumor and clinicopathological parameters or prognosis.

Methods

Subjects were 42 ICC patients who had undergone hepatectomy. microvessel density (MVD) determined by CD34 staining was compared with imaging. Attenuation was calculated in images from multidetector CT of tumor and non-tumorous regions. Enhancement patterns were divided into two groups: arterial enhancement with higher attenuation (>16 HU; Hyper group, n = 12); and arterial enhancement with lower attenuation (Hypo group, n = 30).

Results

Univariate analysis identified high tumor marker level, increased size, less-differentiation, incomplete resection, increased bleeding, and lower MVD as significantly associated with poor survival (p < 0.05). Increased attenuation throughout the whole ICC correlated significantly with radiological findings and MVD. Concomitant hepatitis, well-differentiation, and smaller tumor were more significantly frequent in the Hyper group than in the Hypo group (p < 0.05). Postoperative early recurrence was significantly less frequent in the Hyper group, and overall survival was significantly better in the Hyper group (p < 0.05).

Conclusions

Increased CT attenuation correlated with ICC tumor vascularity. Increased tumor enhancement in the arterial phase was associated with chronic hepatitis, lower malignancy, and better survival.     

Functionalized Magnetonanoparticles in Visualization of Intracranial Tumors on MRI

Purpose

The development of nonradioactive and targeted magnetonanoparticles (MNP) capable of crossing the blood–brain barrier (BBB) and of concentrating in and enhancing the contrast of intracranial tumors on magnetic resonance imaging (MRI).

Procedure

Nonradioactive 2-deoxy-d-glucose (2DG) was covalently attached to magnetonanoparticles composed of iron oxide and dextran and prepared for intravenous (tail) injection in the naïve rats and mouse models of glioma. MR images were acquired at 3 and 7 T.

Results

2DG-MNP increased tumor visibility and improved delineation of tumor margins. Histopathology confirmed that 2DG-MNP crossed the BBB and accumulated within brain parenchyma.

Conclusion

Nonradioactive 2DG-MNP can cross an intact BBB on and improve visualization of tumor and tumor margins on MRI.     

Hybrid method for the detection of pulmonary nodules using positron emission tomography/computed tomography: a preliminary study

Purpose

In this study, an automated scheme for detecting pulmonary nodules using a novel hybrid PET/CT approach is proposed, which is designed to detect pulmonary nodules by combining data from both sets of images.

Methods

Solitary nodules were detected on CT by a cylindrical filter that we developed previously, and in the PET imaging, high-uptake regions were detected automatically using thresholding based on standardized uptake values along with false-positive reduction by means of the anatomical information obtained from the CT images. Initial candidate nodules were identified by combining the results. False positives among the initial candidates were eliminated by a rule-based classifier and three support vector machines on the basis of the characteristic features obtained from CT and PET images.

Results

We validated the proposed method using 100 cases of PET/CT images that were obtained during a cancer-screening program. The detection performance was assessed by free-response receiver operating characteristic (FROC) analysis. The sensitivity was 83.0 % with the number of false positives/case at 5.0, and it was 8 % higher than the sensitivity of independent detection systems using CT or PET images alone.

Conclusion

   Detection performance indicates that our method may be of practical use for the identification of pulmonary nodules in PET/CT images.     

Hepatic pseudolymphoma: imaging–pathologic correlation with special reference to hemodynamic analysis

Objectives

To clarify radiological findings and hemodynamic characteristics of hepatic pseudolymphoma, as compared with the histopathological findings.

Methods

Radiological findings of ten histopathologically confirmed hepatic pseudolymphomas in seven patients were examined using US, CT, and MRI. Six patients also underwent angiography-assisted CT, including CT during arterial portography (CTAP) and CT during hepatic arteriography (CTHA) to analyze hemodynamics.

Results

The nodules were depicted as hypoechoic on US, hypodense on precontrast CT, hypointense on T1-weighted images, and hyperintense on T2-weighted images. On contrast-enhanced CT/MRI, they showed various degrees of enhancement, and sometimes, perinodular enhancement was observed at the arterial dominant and/or equilibrium phase. On CTAP, the nodules showed portal perfusion defects, including some in the perinodular liver parenchyma. On CTHA, irregular bordered enhancement was observed in perinodular liver parenchyma on early phase, and continued until delayed phase. Some nodules had preserved intra-tumoral portal tracts. Histopathologically, the nodules consisted of marked lymphoid cells. In perinodular liver parenchyma, stenosis or disappearance of portal venules, caused by lymphoid cell infiltration in the portal tracts, was observed.

Conclusions

Hepatic pseudolymphoma showed some characteristic radiological findings including hemodynamics on CT, MRI, and angiography-assisted CT. These findings are useful in the differentiation from hepatocellular carcinoma and other tumors.     

Pancreatic neuroendocrine neoplasm: correlation between computed tomography enhancement patterns and prognostic factors of surgical and endoscopic ultrasound-guided fine-needle aspiration biopsy specimens

Purpose

To retrospectively determine whether enhancement patterns in the pancreatic and equilibrium phases of computed tomography (CT) for pancreatic neuroendocrine neoplasms are related to prognostic factors of surgical and endoscopic ultrasound-guided fine-needle aspiration biopsy specimens.

Methods

Twenty-five pancreatic neuroendocrine neoplasms in 22 patients underwent preoperative dynamic CT. Tumors were classified into two groups by enhancement patterns on preoperative CT. A washout pattern was defined as peak enhancement in the pancreatic phase with washout of at least 60 Hounsfield units in the equilibrium phase. Group 1 comprised tumors showing a washout pattern in more than half of tumor and Group 2 comprised tumors showing a washout pattern in less than half of the tumor. The Ki-67 index and the presence of vascular invasion were evaluated in surgical specimens. The Ki-67 index from biopsy specimens was compared with that from surgical specimens.

Results

There were 12 surgical specimens in Group 1 and 13 in Group 2. Group 2 showed significant correlations with larger Ki-67 indices (p < 0.05) and positive vascular invasion (p < 0.05). The Ki-67 index discrepancy between biopsy and surgical specimens of Group 2 was significantly greater than that of Group 1 (p < 0.05).

Conclusions

Pancreatic neuroendocrine neoplasms in which less than half of the tumor showed a washout pattern were correlated with poor prognostic factors. Analysis of enhancement patterns may provide predictive information about whether endoscopic ultrasound-guided fine-needle aspiration biopsy is reliable for the assessment of Ki-67 index.