Value of 3T magnetic resonance dynamic contrast-enhanced and diffusion-weighted imaging in differential diagnosis of musculoskeletal tumors / 中国医学科学院学报

<p><b>OBJECTIVE</b>To evaluate the value of magnetic resonance dynamic contrast-enhanced (MR-DCE) and magnetic resonance diffusion-weighted imaging (MR-DWI) in the differentiation of benign and malignant musculoskeletal tumors.</p><p><b>METHODS</b>Sixty-three patients with pathologically confirmed musculoskeletal tumors were examined with MR-DCE and MR-DWI. Using single shot spin echo planar imaging sequence and different b values of 400, 600, 800 and 1000 s/mm(2), we obtained the apparent diffusion coefficient (ADC) of the lesions. ADC values were measured before and after MR-DCE, with a b value of 600 s/mm(2). The 3D fast acquired multiple phase enhanced fast spoiled gradient recalled echo sequence was obtained for multi-slice of the entire lesion. The time-signal intensity curve (TIC), dynamic contrast-enhanced parameters, maximum slope of increase (MSI), positive enhancement integral, signal enhancement ratio, and time to peak (T(peak)) were also recorded.</p><p><b>RESULTS</b>ADC showed no significant difference between benign and malignant tumors when the b value was 400, 600, 800, or 1000 s/mm(2), and it was not significantly different between benign and malignant tumors in both pre-MR-DCE and post-MR-DCE with b value of 600 s/mm(2). TIC were classified into four types type1 showed rapid progression and gradual drainage; type2 showed rapid progression but had no or slight progression; type 3 showed gradual progression; and type 4 had no or slight progression. Most lesions of type1 or type2 were malignant, whereas most lesions of type 3 or type 4 were benign. When using type1 and type 2 as the standards of malignancy, the diagnostic sensitivity and specificity was 87.23% and 50.00%, respectively. The types of TIC showed significant difference between benign and malignant musculoskeletal tumors(χ(2)=17.009,P=0.001). When using MSI 366.62 ± 174.84 as the standard of malignancy, the diagnostic sensitivity and specificity was 86.78% and 78.67%, respectively. When using T(peak)≤70s as the standard of malignancy, the diagnostic sensitivity and specificity was 82.89%and 85.78%, respectively. Positive enhancement integral and signal enhancement ratio showed no significant difference between benign and malignant musculoskeletal tumors.</p><p><b>CONCLUSIONS</b>TIC, MSI and T(peak) of MR-DCE are valuable in differentiating benign from malignant musculoskeletal tumors. T(peak) has the highest diagnostic specificity, and TIC has the highest diagnostic sensitivity. The mean ADC value are no significant difference between benign and malignant tumors.</p>

Multi-slice helical CT perfusion imaging in evaluating intracranial neoplasms and tumor-like lesions / 中华肿瘤杂志

<p><b>OBJECTIVE</b>To investigate the clinical value of CT perfusion in diagnosing and assessing intracranial neoplasms and tumor-like lesions.</p><p><b>METHODS</b>16-slice helical CT perfusion imaging was performed in 56 patients who were clinically suspected to have intracranial neoplasm or tumor-like lesion. With a GE-Light Speed 16-slice helical CT scanner, routine plain-CT scanning was performed to localize the central slice of the lesion. Perfusion imaging was then carried out using cine scan technique to maintain a slice thickness of 5-10 mm, a total dose of 50-70 ml of contrast-medium at an injection flow rate of 3-5 ml/s, a delay time of 7 s and a total scan time of 50 s. The images were processed using perfusion software in an ADW 4.0 workstation, meanwhile, time-density curves (TDC) of different kinds of lesions were also produced and analyzed.</p><p><b>RESULTS</b>The pathological types in this series included: 29 gliomas (12 low-grade and 17 high-grade), 2 ependemomas, 2 hemangioblastomas, 1 medulloblastoma, 2 metastatic tumors, 1 lymphoma, 5 meningiomas, 2 schwannomas, 1 germinoma, 1 teratoma in the pineal region, 6 cavernous hemangiomas, 2 inflammatory granulomas, 1 tuberculoma, and 1 hyperplasia of the choroid plexus. TDC of high-grade glioma, low-grade glioma and meningioma was different from each other. The cerebral blood flow (CBF), cerebral blood volume (CBV), particularly, the permeability surface (PS) value of glioma was found to increase significantly with the escalation of tumor differentiation grade. In PS map, margin of the tumor could be clearly showed, which was very useful when hemorrhaging within the tumor occurred. CBF in meningioma was lower than that in high-grade glioma, but there was no statistical difference in CBV, MTT and PS between these two types of tumor. The features of intracranial cavernous hemangioma such as significant prolongation of MTT, different TDCs, and zero perfused areas were diverse on CTP image, which was helpful in differentiating it from the other lesions. The germinoma and teratoma had rather low CBF and CBV value, but a remarkably high PS value, furthermore, they showed a rapid escalated TDC with a slowly and continuously elevated platform. The perfusion features of schwannoma was concordant with its pathological findings. However, no visible specific feature of inflammatory lesion was found on CTP image in this series.</p><p><b>CONCLUSION</b>Multi-slice helical CT perfusion imaging may be helpful in revealing histopathological features and hemodynamic changes as well as differential diagnosis of intracranial neoplasms and tumor-like lesions. When combined with other image and clinical information, CTP can play an important role in pre-operative diagnosis and treatment planning for intracranial neoplasms and tumor-like lesions.</p>

Malignant tumor with false negative 18F-FDG PET image / 中华肿瘤杂志

<p><b>OBJECTIVE</b>To investigate the FDG uptake characteristics, the factors affecting 18F-FDG uptake and the extra CT diagnostic value of 18F-FDG PET/CT scan in the malignant tumor with false negative 18F-FDG PET image.</p><p><b>METHODS</b>The data of PET/CT image in 17 patients with various kinds of cancers were reviewed and analyzed by visual observation and semi-quantity analysis ( SUV). The results were compared with the CT and histopathological diagnosis, respectively.</p><p><b>RESULTS</b>Of 6 well-differentiated HCC patients confirmed by histopathological diagnosis, one had two lesions in the right lobe of the liver. One of these two lesions showed low FDG uptake on 18F-FDG PET scan and low density on CT scan. The other one was not shown on either 18F-FDG PET or plain CT scan. But on enhanced CT scan, these two lesions were found to be inhomogeneous with high density at arterial phase. The false negative 18F-FDG PET images of one gastric signet ring cell carcinoma in the gastric fundus with right adnexa metastasis, 3 renal cell carcinoma, one greater omentum and peritoneal metastatic adenocarcinoma and one well-differentiated prostate cancer were caused by normal physical uptake in the digestive tract or FDG retention in the urinary system due to normal excretion. The size of three metastases was smaller than or equal to 1 cm in diameter, however, two primary lesions of these metastases showed high FDG uptake and only one was negative on either 18F-FDG PET or CT scan. In this series, 68.8% of the primary tumors and 66.7% of metastases were found to show abnormal density on CT scan, and 31. 2% of the primary tumors and 33. 3% of metastases were not detectable on either PET or CT images.</p><p><b>CONCLUSION</b>False negative 18F-FDG PET in malignant tumor may be correlated with the pathologic type, differentiation degree and the lesion size. Combining CT information with PET or paying attention to the scan methods during 8 F-FDG PET examination may reduce the rate of false negative 18F-FDG PET diagnosis in various kinds of malignant tumors.</p>

Study on imaging parameters of multi-slice spiral CT long coverage angiography in intracranial and cervical arteries / 中华放射学杂志

Objective To explore application of the bolus-triggered technique and optimal match between collimation and pitch of MSCTA in intracranial and cervical arteries.Methods(1)The small-dose tests were performed in 19 healthy volunteers and the theoretical threshold was obtained by the time-density curve.(2)forty healthy volunteers were divided randomly into two groups and the scanning parameters were as follows.Group A:collimation 1.0 mm,pitch 1.750. Group B:collimation 2.5 mm,pitch 0.625. Statistical significance was determined with the X~2 test and t test(?=0.05).Results(1)In 19 volunteers,CT value 4 seconds before the peak was 75 HU,the CT value at the beginning segment of the carotid artery and the C_1 segment of internal carotid artery was in accordance with the standard.(2)Image quality ofⅠ,Ⅱgrades artery structures of group B was superior to that of group A.Image quality ofⅢ,Ⅴ grades artery structures of group A was superior to that of group B.Conclusions(1)MSCTA in intracranial and cervical arteries can display systematically the cerebral and carotid arteries.(2)The bolus-triggered technique can improve the image quality of the target vessels.The image quality of the MSCTA of intracranial and cervical arteries is better with the threshold of 75 HU on the basis of 3.5 ml/s injection rate.(3)On the basis of the same other parameters,the optimal scanning parameters are a collimation of 1.0 mm with a pitch of 1.750.