Imaging and localization of islet-cell tumours of the pancreas on CT and MRI

Islet-cell tumours are neuroendocrine tumours that arise from the endocrine pancreas. They may be associated with a variety of syndromes and are subclassified into functioning and non-functioning tumours. They range from benign to malignant. They demonstrate characteristic features when imaged with both computed tomography (CT) and magnetic resonance imaging (MRI). Sensitivity and specificity, as well as detection of extrapancreatic extension, are generally superior with MRI. However, CT is currently still more readily available to patients. Multiphase, post-contrast series are commended for the evaluation of islet-cell tumours with either modality.     

Interstudy reproducibility of dimensional and functional measurements between cine magnetic resonance studies in the morphologically abnormal left ventricle

The validity of geometric formulas to derive mass and volumes in the morphologically abnormal left ventricle is problematic. Imaging techniques that are tomographic and therefore inherently three-dimensional should be more reliable and reproducible between studies in such ventricles. Determination of reproducibility between studies is essential to define the limits of an imaging technique for evaluating the response to therapy. Sequential cine magnetic resonance (MR) studies were performed on patients with dilated cardiomyopathy (n = 11) and left ventricular hypertrophy (n = 8) within a short interval in order to assess interstudy reproducibility. Left ventricular mass, volumes, ejection fraction, and end-systolic wall stress were determined by two independent observers. Between studies, left ventricular mass was highly reproducible for hypertrophied and dilated ventricles, with percent variability less than 6%. Ejection fraction and end-diastolic volume showed close reproducibility between studies, with percent variability less than 5% End-systolic volume varied by 4.3% and 4.5% in dilated cardiomyopathy and 8.4% and 7.2% in left ventricular hypertrophy for the two observers. End-systolic wall stress, which is derived from multiple measurements, varied the greatest, with percent variability of 17.2% and 15.7% in dilated cardiomyopathy and 14.8% and 13% in left ventricular hypertrophy, respectively. The results of this study demonstrate that mass, volume, and functional measurements are reproducible in morphologically abnormal ventricles.     

Induction and repair of DNA double-strand breaks in blood lymphocytes of patients undergoing 18F-FDG PET/CT examinations

Purpose

The purpose of this study was to evaluate DNA double-strand breaks (DSBs) in blood lymphocytes of patients undergoing positron emission tomography (PET)/CT using γ-H2AX immunofluorescence microscopy and to differentiate between ¹⁸F-fluorodeoxyglucose (FDG) and CT-induced DNA lesions.

Methods

This study was approved by the local Ethics Committee and complies with Health Insurance Portability and Accountability Act (HIPAA) requirements. After written informed consent was obtained, 33 patients underwent whole-body ¹⁸F-FDG PET/CT (3?MBq/kg body weight, 170/100 reference mAs at 120?kV). The FDG PET and CT portions were performed as an initial CT immediately followed by the PET. Blood samples were obtained before, at various time points following ¹⁸F-FDG application and up to 24?h after the CT scan. Distinct foci representing DSBs were quantified in isolated lymphocytes using fluorescence microscopy after staining against the phosphorylated histone variant γ-H2AX.

Results

The DSB values at the various time points were significantly different (p?<?0.001). The median baseline level was 0.08/cell (range 0.06–0.12/cell). Peaks of radiation-induced DSBs were found 30?min after ¹⁸F-FDG administration (median excess foci 0.11/cell, range 0.06–0.27/cell) and 5?min after CT (median excess foci 0.17/cell, range 0.05–0.54/cell). A significant correlation between CT-induced DSBs and dose length product was obtained (ρ?=?0.898, p?<?0.001). After 24?h DSB values were still slightly but significantly elevated (median foci 0.11/cell, range 0.10–0.14/cell, p?=?0.003) compared to pre-exposure levels.

Conclusion

PET/CT-induced DSBs can be monitored using γ-H2AX immunofluorescence microscopy. Peak values may be obtained 30?min after ¹⁸F-FDG injection and 5?min after CT. The radionuclide contributes considerably to the total DSB induction in this setting.     

Liver adenomatosis: serial investigation on MRI

Purpose

To describe the natural history of liver adenomatosis (LA), including complications and changes in lesion size over time.

Materials and methods

Eighteen patients with clinical diagnosis of LA were included. Clinical and biochemical information were collected. The initial and follow-up MR studies were reviewed retrospectively to determine change in lesion size and imaging features.

Results

Seventeen patients were women (94.4%). The mean age of the initial MR study was 37.0 years (18–52 years). The median size of the largest lesion was 6.7 cm (range 3.0–13.5 cm). Intratumoral bleeding was detected on MRI in 9 lesions, in 7 patients (38.8%). The median size for hemorrhagic lesions was 7.6 cm (range 4.1–13.5 cm). During the mean follow-up period of 29.4 (range 4–98) months, 10 patients had stable disease (55.6%), and 8 patients had tumor regression (44.4%). Of 8 patients who were followed without intervention, 3 patients (37.5%) had spontaneous regression. No malignant transformation or lesion progression was occurred.

Conclusion

During an over 2-year follow-up period, the majority of lesions of LA appeared to remain stable or showed tumor regression. Spontaneous tumor regression can be observed in approximately 37% of individuals in the age range of 28–53 years.     

Perilesional enhancement of liver cavernous hemangiomas in magnetic resonance imaging

Objective

To evaluate on magnetic resonance imaging (MRI) the occurrence rate of temporal perilesional parenchymal enhancement (PPE) associated with hepatic hemangiomas in a large consecutive series and to determine which aspects are associated with this observation.

Materials and methods

Institutional review board approved this retrospective study. A computerized search of the MRI database was performed for consecutive patients between January 2008 and January 2012. The study population included 513 liver hemangiomas in 224 patients (104 males and 120 females; mean age of 55.2 ± 13.5 years; age range 24–89 years). Two readers independently reviewed the frequency of PPE, size, speed of enhancement and location of each hemangioma. Marginal models with generalized estimating equation were used. Wald test was applied to verify if the model coefficients were significant.

Results

80/513 (15.6%) hemangiomas showed PPE. The incidence of PPE was significantly higher (p < 0.05) in hemangiomas with Type1 speed of enhancement (51/80, 63.8%) than in those with Type2 or Type3. 66/80 (82.5%) hemangiomas with PPE were subcapsular (p < 0.05). Conversely, the majority (280/433, 64.7%) of hemangiomas without PPE were deep in location (p < 0.001). Lesser proportion of hemangiomas with PPE was located in segment IVa (p < 0.05).

Conclusion

PPE is not uncommonly seen along with hepatic hemangiomas. This appearance is most frequently observed in rapidly enhancing small lesions with a subcapsular location.     

Multilocular cystic nephroma: MR imaging appearance with current techniques,including gadolinium enhancement

The purpose of the study was to define the MRI appearance of multilocular cystic nephroma (MLCN), using current MR techniques, including gadolinium (Gd)-enhanced sequences. Seven patients with MLCN underwent MR imaging with the following sequences: T1-weighted spin echo with fat suppression (TIFS, five patients), T1-weighted spoiled gradient echo (SGE, seven patients), T2-weighted fast spin echo (two patients), and Gd-enhanced TIFS (seven patients) and SGE (seven patients). MLCN was histologically proven by resection of the mass in six patients and by observation of typical imaging features with stability in appearance over a 6-month period in one patient. Lesion morphology and signal intensity (SI) features were retrospectively evaluated. MRI features of MLCN included a solitary cystic lesion with thin internal septations in six patients and a cluster of closely grouped cysts similar in size in one patient. Individual cystic spaces demonstrated SI, varying from low to high on T1-weighted images in three patients and demonstrated low-to-intermediate SI in four patients. Herniation of the lesions into the renal collecting system and thin enhancing septa were demonstrated in all patients. A complex cystic renal lesion with enhancing septa and herniation into the renal collecting system are the characteristic MR findings of MLCN. The direct multiplanar capability of MR may optimally show the relationship of MLCN to the renal pelvis and, thus, facilitate correct diagnosis.     

Accuracy of magnetic resonance imaging for preoperative detection of portal vein thrombosis in liver transplant candidates.

The detection of main portal vein thrombosis (PVT) on preoperative imaging of liver transplant candidates has important technical implications for the transplantation procedure. Data are scarce regarding the accuracy of magnetic resonance imaging (MRI) at detecting PVT. The aim of our study was to compare preoperative findings of the portal vein on MRI to operative findings at liver transplantation. Abdominal MRI and clinical records of 172 consecutive patients who received liver transplants between January 1999 and September 2004 were reviewed. Two radiologists independently evaluated the last abdominal magnetic resonance examinations obtained before liver transplantation, blinded to the original reading, operative findings, and clinical data. Findings on MRI were compared with intraoperative findings at transplantation. Main PVT was detected in 12 patients, in whom 8 were found to have thrombus at surgery, with 6 requiring a jump graft or thrombectomy. Sensitivity and specificity of MRI for detecting main PVT were 100% and 98%, respectively. The cause of discordance between findings on MRI and at transplantation in 2 cases was a diminutive caliber of the main portal vein that was interpreted as recanalized chronic thrombosis on MRI. In conclusion, in our study group MRI detected PVT in all liver transplant recipients requiring jump grafts at transplantation. The major reason for a false-positive MRI was a diminutive but patent portal vein.     

HASTE MR imaging: Description of technique and preliminary results in the abdomen

HASTE (HAlf fourier Single-shot Turbo spin-Echo) is a single-section T2-weighted sequence that acquires images in less than 1 second. Images are breathing independent and possess a variety of other features useful for imaging the abdomen. The design of this technique is described. Clinical studies of 38 consecutive patients were performed using this technique. HASTE images were considered good in 28 and fair in 10 patients, including five patients who could not suspend respiration. Definition of liver and bowel was particularly clear.     

Malignant fibrous histocytoma of the inferior vena cava: appearances on contrast-enhanced spiral CT and MRI

Primary malignant tumors of the inferior vena cava are infrequent. We report a very rare case of primary malignant fibrous histiocytoma of the inferior vena cava and describe the contrast-enhanced spiral computed tomographic and magnetic resonance imaging findings. Received: 16 March 1995/Accepted: 23 April 1995