Xiang-Ming Fang

Diffusion-weighted MR imaging for detection of extrahepatic cholangiocarcinoma

OBJECTIVES To measure the sensitivity of diffusion-weighted imaging (DWI) and determine the most appropriate b value for DWI; to explore the correlation between the apparent diffusion coefficient (ADC) value and the degree of extrahepatic cholangiocarcinoma differentiation. METHODS Preoperative diffusion-weighted imaging and magnetic resonance examinations were performed for 31 patients with extrahepatic cholangiocarcinoma. Tumor ADC values were measured, and the signal-to-noise ratio, contrast-to-noise ratio, and signal-intensity ratio between the diffusion-weighted images with various b values as well as the T2-weighted images were calculated. Pathologically confirmed patients were pathologically graded to compare the ADC value with different b values of tumor at different degrees of differentiation, and the results were statistically analyzed by using the Friedman test. RESULTS A total of 29 cases of extrahepatic cholangiocarcinoma were detected by DWI. As the b value increased, tumor signal-to-noise ratio and contrast-to-noise ratio between the tumor and normal liver gradually decreased, but the tumor signal-intensity ratio gradually increased. When b=800 s/mm2, contrast-to-noise ratio between tumor and normal liver, tumor signal-intensity ratio, and tumor signal-to-noise ratio of diffusion-weighted images were all higher than those of T2-weighted images; the differences were statistically significant (P<0.05). As the b value increased, the tumor ADC value gradually declined. As the degree of differentiation decreased, the tumor ADC value declined. CONCLUSION The b value of 800 s/mm2 was the best in DWI of extrahepatic cholangiocarcinoma; the lesion ADC value declined as the degree of cancerous tissue differentiation decreased.

Intraparenchymal epidermoid cysts in the brain: diagnostic value of MR diffusion-weighted imaging

AIM To evaluate the value of magnetic resonance (MR) diffusion-weighted imaging (DWI) and apparent diffusion coefficients (ADC) maps in the diagnosis of intraparenchymal epidermoid cysts (ECs). MATERIALS AND METHODS Six cases of histopathologically proven intraparenchymal ECs were studied. All patients were examined with conventional MR (T1WI, T2WI, contrast-enhanced T1WI) and DWI sequences. Along with the mean ADC values (mADC) of the ECs, the cerebrospinal fluid (CSF) and grey matter (GM) were measured. Qualitative and quantitative assessments, as well as MRI findings, were retrospectively analysed using a double blind method by three radiologists in consensus. RESULTS Four lesions were located in the cerebellum, among them, one was accompanied by an arachnoid cyst; one huge lesion crossed the parenchyma of the frontal and temporal lobes; the other was located in the left temporal lobe. Two lesions had a homogeneous CSF-like intensity on both T1WI and T2WI. The other four were of mixed-intensity on both T1WI and T2WI. All lesions were strikingly hyperintense on DWI, and iso- or slightly hypointense on ADC (relative to the brain). The mADCs of the ECs were significantly higher than that of GM, but significantly lower than that of CSF. Three cases (3/6) were accurately diagnosed using conventional MR sequences without DWI, but in the remaining three cases, correct diagnosis could only be made with help of DWI. CONCLUSION DWI sequences can facilitate the diagnosis of intraparenchymal ECs, thus alerting surgeons of the risk of chemical meningitis at surgery. The MR findings of intraparenchymal ECs are basically as the same as those of extracerebral ECs, but the former is likely to have a mixed signal. The hyperintense signal of ECs on DWI is probably caused by the T2 shine-through effect in tumour tissue.

CT imaging and histopathological features of renal epithelioid angiomyolipomas

AIM To describe computed tomography (CT) imaging and histopathological manifestations of renal epithelioid angiomyolipomas (EAMLs) for better understanding and cognition in the diagnosis of this new category of renal tumours. MATERIALS AND METHODS Clinical data and CT images from 10 cases of EAML were retrospectively analysed. All patients underwent CT with and without contrast medium administration, with multiplanar reconstruction (MPR) when needed. RESULTS Plain CT manifestations of EAMLs were a higher density of mass (10-25 HU) than renal parenchyma, bulging contour of the involved kidney, absence of fat, distinct edges without a lobulate appearance. Contrast-enhanced CT features were markedly heterogeneous enhancement (from rapid wash-in to slow wash-out), large tumour size without lobular appearance, complete capsule with distinct margins and frequent mild necrotic areas. Histopathological features were epithelioid cells with eosinophilic cytoplasm, large and deeply stained nuclei, and dense arrangement of tumour cells with patchy necrosis; diffuse sheets of epithelioid cells were positive for HMB-45 (melanoma-associated antigen) and negative for epithelial membrane antigen (EMA) staining. CONCLUSION Multiple specific CT features correlated well with the histopathology and may play an important role in the primary diagnosis of EAMLs.

A massive renal epithelioid angiomyolipoma with multiple metastatic lymph nodes

A 47-year-old man presented with dull pain in the left upper abdomen for 1 year. Computed tomograph (CT) examination revealed a very large heterogeneously enhancing mass in the left kidney, measuring up to 28 cm. The mass was accompanied by several enlarged lymph nodes in the peri-aortic region. Radical nephrectomy was performed and pathologic evaluation revealed sheets of epithelioid cells and piecemeal necrosis consistent with malignant epithelioid angiomyolipoma (EAML) with regional lymph node metastases. The tumor cells were strongly positive for human melanosome-associated protein (HMB-45) on immunohistochemical staining. There was neither metastasis nor recurrence 2 years postoperatively. EAML is a rare tumor of mesenchymal tissue with potential for aggressive behavior. If this neoplasm is suspected based on CT features, EAML should be confirmed by pathology and immunohistochemistry.

Efficacy of dual-source CT coronary angiography in evaluating coronary stenosis: initial experience

OBJECTIVE To retrospectively assess the diagnostic efficacy of dual-source CT angiography (DSCTA) in detecting and grading coronary stenosis. METHODS Institutional review board approval and informed consent were obtained. One hundred ten patients were performed with both DSCTA and conventional coronary angiography (CCA) without heart rate or rhythm control in 1 week. Regarding CCA as the gold standard, the assessable rate of coronary arteries and diagnostic value of coronary stenosis using DSCTA were analyzed, respectively. The intermodality agreement between DSCTA and CCA in grading coronary stenosis was assessed using kappa test. The value of DSCTA in diagnosing >50% coronary stenoses was also assessed. RESULTS The overall assessable rate of DSCTA was 98.6% in detecting coronary arteries; there was no significant difference between assessable rates from different groups of heart rate (chi(2)=0.45, P > .05). The efficacy of DSCTA was of 97.9% sensitivity, 97.3% specificity, 90.4% positive predictive value, and 99.4% negative predictive value for coronary stenosis; and 94.7% sensitivity, 96.8% specificity, 83.7% positive predictive value, and 99% negative predictive value for >50% stenoses. The intermodality agreement in diagnosing coronary stenosis was satisfactory (k=0.87, u=58.46, P<.01). CONCLUSIONS As an effective noninvasive diagnostic tool, DSCTA yields a promising accuracy and reliability in assessing coronary stenosis. It may be recommended as a valuable screening tool for coronary artery disease, and a potential challenge to CCA as well.

MRI Features of Spinal Epidural Angiolipomas

Objective To describe the MRI findings in ten patients of spinal epidural angiolipoma for differentiated diagnosis presurgery. Materials and Methods Ten surgically proved cases of spinal epidural angiolipomas were retrospectively reviewed, and the lesion was classified according to the MR findings. Results Ten tumors were located in the superior (n = 4), middle (n = 2), or inferior (n = 4) thoracic level. The mass, with the spindle shape, was located in the posterior epidural space and extended parallel to the long axis of the spine. All lesions contained a fat and vascular element. The vascular content, correlating with the presence of hypointense regions on T1-weighted imaging (T1WI) and hyperintense signals on T2-weighted imaging, had marked enhancement. However, there were no flow void signs on MR images. All tumors were divided into two types based on the MR features. In type 1 (n = 3), the mass was predominantly composed of lipomatous tissue (> 50%) and contained only a few small angiomatous regions, which had a trabeculated or mottled appear. In type 2 (n = 7), the mass, however, was predominantly composed of vascular components (> 50%), which presented as large foci in the center of the mass. Conclusion Most spinal epidural angiolipomas exhibit hyperintensity on T1WI while the hypointense region on the noncontrast T1WI indicates to be vascular, which manifests an obvious enhancement with gadolinium administration.

Early detection of acute radiation-induced lung injury with multi-section CT perfusion imaging: An initial experience

AIM To explore the value of 64-section computed tomography (CT) perfusion imaging (CTPI) in the early diagnosis of acute radiation-induced lung injury (ARILI). MATERIALS AND METHODS Fifty-one patients with oesophageal cancers or malignant thymomas received postoperative radiation therapy with a 60-62 Gy dose and underwent CTPI at pre- and post-radiation therapy time points (week 0, week 4, week 8, and week 12 respectively). The CTPI values were prospectively compared and analysed in order to evaluate the diagnostic utility of CTPI in the early diagnosis of ARILI. RESULTS Eighteen cases (18/51) of ARILI were diagnosed. The mean values of relative regional blood flow (rrBF), relative regional volume (rrBV), and relative regional permeability surface (rrPS) in the ARILI group were correspondingly higher than those of the non-ARILI group. At week 4, rrBF, rrBV, and rrPS in the ARILI group were significantly higher than those at pre-radiation (each p < 0.05). In the non-ARILI group, rrBF and rrBV were higher than those at pre-radiation (each p < 0.05); however, rrPS was not statistically different from that of pre-irradiation. Applying the diagnostic threshold value of rrPS = 1.22, the sensitivity, specificity, and positive and negative predictive values of CTPI for early diagnosis of ARILI were better than those of CT. CONCLUSION CTPI metrics may reflect haemodynamic changes in the post-irradiation lung and can detect cases of early ARILI that appear normal at CT. CTPI is a promising technique for early diagnosis of ARILI.

Submillisievert coronary CT angiography with adaptive prospective ECG-triggered sequence acquisition and iterative reconstruction in patients with high heart rate on the dual-source CT.

PURPOSE To assess the application value of submillisievert coronary CT angiography (CCTA) in patients with a high heart rate (HR) acquired with adaptive prospective ECG-triggered sequence acquisition and iterative reconstruction on the secondary generation dual-source CT. MATERIALS AND METHODS A total of 120 consecutive high-HR patients suspected with coronary artery disease underwent CCTA and invasive coronary angiography (ICA) within two weeks. Patients were randomly assigned into three groups: group A (n = 40), where the patients underwent retrospectively ECG-triggered acquisition CCTA at 100 kVp; group B (n = 40), where the patients received adaptive prospective ECG-triggered sequence acquisition at 100 kVp; and group C (n = 40), where the patients performed adaptive prospective ECG-triggered sequence acquisition at 80 kVp with iterative reconstruction. The mean CT values, signal noise ratios (SNR) and contrast noise ratios (CNR) in the ascending aorta and coronary arteries of the three groups were measured and compared. The image quality and radiation dose among the three groups were compared. The consistency of displaying the coronary stenosis of each group was assessed compared with the results of ICA as the gold standard. RESULTS There was no significant difference in gender, age and body mass index (BMI) (all P > 0.05). The mean attenuations, SNRs and CNRs in the ascending aorta and coronary artery were not significantly different between group A and group B (P > 0.05). The mean attenuations of group C were significantly higher than group A and group B (P < 0.01), but the image noise and CNR were significantly lower in group C (P < 0.01). The number of appreciable segments among the three groups was not significantly different on a per-segment and per-vessel basis (P > 0.05). The subjective image quality among the three groups was not significantly different (P > 0.05). With the ICA result as a reference standard, there was good consistency in the evaluation of the coronary stenosis degree between CCTA and ICA (r > 0.75), as well as in the assessment of the coronary stenosis rate using the Bland- Altman analysis. The mean radiation dose in group B was half of that in group A. Moreover, the mean radiation dose in group C was less than one sixth of that in group A and less than 1 mSv (0.7±0.2 mSv). CONCLUSIONS For patients with high HR, adaptive prospective ECG-triggered sequence acquisition on the FLASH dual-source CT results in equal image quality and half of the radiation dose reduction compared with retrospectively ECG-triggered spiral acquisition at the same tube voltage (100 kVp) and same R-R interval of exposure. In addition, adaptive prospective ECG-triggered sequence acquisition combined with low tube voltage and iterative reconstruction can further reduce the radiation dose to the submillisievert level without compromising image quality and the accuracy of assessing the coronary stenosis degree, and can be popularized as a routine technique.

Analysis of the mismatched manifestation between rCBF and rCBV maps in cerebral astrocytomas.

OBJECTIVE To explore the mismatched manifestation between regional cerebral blood flow (rCBF) and regional cerebral blood volume (rCBV) of astrocytomas. METHODS Both conventional and perfusion CT were performed on 29 patients with pathologically confirmed astrocytomas (15 cases in Grades I-II, 14 cases in Grades III-IV). Time-density curves were plotted, cerebral blood flow and volume maps were generated, and the values between rCBF and rCBV in the same region of interest (ROI) were compared. RESULTS Twelve low-grade astrocytomas showed low or medium values of both rCBF (46.95+/-22.92 ml 100 g(-1) mm(-1)) and rCBV (5.74+/-3.61 ml 100 g(-1)); 12 high-grade astrocytomas showed high values of both rCBF (95.44+/-42.58 ml 100 g(-1) min(-1)) and rCBV (9.24+/-5.32 ml 100g(-1)). These cases exhibited agreement between the values of rCBF and rCBV. However, the remaining five astrocytomas were mismatched, showing reduced rCBF value and increased rCBV value in the same ROI. The discrepancy may mislead to an inaccuracy of perfusion CT in grading gliomas. CONCLUSIONS The mismatched manifestation between rCBF and rCBV occasionally exists in some areas of astrocytomas. Hence, attention should be paid to assessments in preoperative grading of astrocytomas and in monitoring therapeutic effects.

An Appreciation for the Rabbit Ladderlike Modeling of Radiation-induced Lung Injury with High-energy X-Ray.

Background:To evaluate the utility of rabbit ladderlike model of radiation-induced lung injury (RILI) for the future investigation of computed tomography perfusion. Methods:A total of 72 New Zealand rabbits were randomly divided into two groups: 36 rabbits in the test group were administered 25 Gy of single fractionated radiation to the whole lung of unilateral lung; 36 rabbits in the control group were sham-radiated. All rabbits were subsequently sacrificed at 1, 6, 12, 24, 48, 72 h, and 1, 2, 4, 8,1 6, 24 weeks after radiation, and then six specimens were extracted from the upper, middle and lower fields of the bilateral lungs. The pathological changes in these specimens were observed with light and electron microscopy; the expression of tumor necrosis factor-&agr; (TNF-a) and transforming growth factor-&bgr;1 (TGF-&bgr;1) in local lung tissue was detected by immunohistochemistry. Results:(1) Radiation-induced lung injury occurred in all rabbits in the test group. (2) Expression of TNF-a and TGF-&bgr;1 at 1 h and 48 h after radiation, demonstrated a statistically significant difference between the test and control groups (each P < 0.05). (3) Evaluation by light microscopy demonstrated statistically significant differences between the two groups in the following parameters (each P < 0.05): thickness of alveolar wall, density of pulmonary interstitium area (1 h after radiation), number of fibroblasts and fibrocytes in interstitium (24 h after radiation). The test group metrics also correlated well with the time of postradiation. (4) Evaluation by electron microscopy demonstrated statistically significant differences in the relative amounts of collagen fibers at various time points postradiation in the test group (P < 0.005), with no significant differences in the control group (P > 0.05). At greater than 48 h postradiation the relative amount of collagen fibers in the test groups significantly differ from the control groups (each P < 0.05), correlating well with the time postradiation (r = 0.99318). Conclusions:A consistent and reliable rabbit model of RILI can be generated in gradient using 25 Gy of high-energy X-ray, which can simulate the development and evolution of RILI.