[Differentiation of axillary inflammatory and metastatic lymph nodes with diffusion-weighted imaging in animal modes].

OBJECTIVE: To evaluate the value of diffusion-weighted imaging (DWI) in the differentiation of axillary inflammatory hyperplastic and metastatic lymph nodes. METHODS: Forty female New Zealand white rabbits were divided randomly into 2 groups (n = 20 each). And the animal models of axillary inflammatory hyperplastic and metastatic lymph nodes were established. All successfully implanted models received conventional magnetic resonance imaging (MRI) and diffusion-weighted imaging (DWI) examinations. The features of signal intensity and shapes of lymph nodes were observed in two groups. The sizes of lymph nodes were measured on the selected axial T(2)WI. The signal intensity and appearance diffusion coefficient (ADC) value of lymph nodes and dorsal muscle at the same slice were measured on the selected T(2)WI, DWI and ADC map respectively. The relative signal intensity (rSIT(2)WI, rSIDWI) and relative ADC (rADC) value of lymph nodes to dorsal muscle were calculated and compared. The diagnostic efficacy of differentiating benign and malignant lymph nodes was analyzed with rADC value through the receiver operating characteristic curve. The correlation between rADC value and cell density was assessed with pathological findings as reference standard. RESULTS: The differences of size, rSIT(2)WI and rSIDWI were not statistically significant between two groups. The rADC value of inflammatory lymph nodes was greater than that of metastatic lymph nodes (0.91 ± 0.14 vs 0.64 ± 0.18). Significant difference existed (t = 3.879, P = 0.03). But there was a little overlap between two groups. With 0.78 as the diagnostic threshold of rADC value, the sensibility and specificity was 86.2% and 74.4% respectively. The correlation between rADC value and cell density of inflammatory hyperplastic and metastatic lymph nodes was significantly inverse (r = -0.53, P = 0.003). CONCLUSIONS: As compared with the routine MRI sequence, rADC value has a higher diagnostic efficacy in the differentiation of benign and malignant lymph nodes. Cell density may be the most important influencing factor for the differences of rADC value between two groups of lymph nodes.

[Value of diffusion weighted imaging in diagnosis of nodular lesions of thyroid: a preliminary study].

OBJECTIVE: To investigate the value of magnetic resonance diffusion weighted imaging (DWI) in the differential diagnoses of malignant and benign thyroid lesions. METHODS: Using echo planner imaging sequence with b value of 0, 100, 200, 300 and 400 s/mm(2) respectively, DWI was performed in 60 patients of focal thyroid lesions. The diagnosis was confirmed by pathological examination (benign, n = 30; malignant, n = 30). Apparent diffusion coefficient (ADC) values were measured. The differences were analyzed between two groups. RESULTS: With b value of 0, 100, 200, 300 and 400 s/mm(2) respectively, there were statistical differences in ADC values between benign and malignant lesions. The ADC value of malignant lesions was smaller than that of benign lesions (P < 0.05). Among different b values, 400 s/mm(2) was the most optimal one to diagnose thyroid nodular lesions. DWI with a b value of 400 s/mm(2) had a proper signal-to-noise ratio (SNO). And ADC value could be measured correctly. With a b value of 400 s/mm(2) and ADC of 1.475 × 10(-3) mm(2)/s, receiver operating characteristic curve was plotted. In the diagnosis of malignant lesions, the sensitivity and specificity were 93.3% and 96.7% respectively. CONCLUSIONS: The ADC value of malignant thyroid nodular lesions is smaller than that of benign lesions. The values of DWI and ADC are important in the differential diagnoses of nodular thyroid lesions.

[Correlation between MR diffusion weighted imaging with malignant degree of rabbit liver VX2 tumor models].

OBJECTIVE: To investigate the correlation between MR diffusion weighted imaging with cellularity and PCNA-LI of rabbit liver VX2 tumor models in different periods. METHODS: 38 successful implanted rabbits were assigned randomly into 2 equal groups and were performed MR DWI in different periods (14 and 21 d) after implantation respectively. Specimens of all tumors were stained with HE and PCNA-LI after MR examination. RESULTS: (1) The ADC value (x 10(-3) mm2/s) in surrounding solid components of liver VX2 tumors in the group of 21 d was lower than that of the group of 14 d (0.77 +/- 0.19 vs 1.00 +/- 0.24, P = 0.007); (2) the cellularity and PCNA-LI in surrounding solid components of liver VX2 tumors in the group of 21 d were higher than those of the group of 14 d respectively (63% +/- 7% vs 43% +/- 10%, P = 0.011; 80% +/- 11% vs 56% +/- 8%, P = 0.008); (3) there were negative correlation between ADC value and cellularity, PCNA-LI of the solid components of the tumors (r = - 0.695, P = 0.000; r = -0. 698, P = 0.000). CONCLUSION: The cellularity may be the most important factor that affects ADC value in solid components of liver VX2 tumors. Since the degree of malignancy is closely connected with cellularity and PCNA labeling index, ADC value measurement may be a new method which could predict the degree of malignancies in vivo.

Systemic disseminated tuberculosis mimicking malignancy on F-18 FDG PET-CT.

FDG PET-CT imaging is increasingly accepted as a modality for evaluation of many malignancies, but FDG also can be accumulated intensely by inflammatory lesions. We present a case of a 60-year-old woman with intermittent fever, chills, fatigue, and dyschezia. CT scans indicated colon carcinoma with thoracic and retroperitoneal lymph node metastases. Whole body FDG PET-CT was performed to confirm and stage the malignant disease and showed intense FDG uptake in those lesions. However, histopathology confirmed tuberculosis. The literature describing FDG accumulation in constitutional tuberculous lesions is sparse, and one must be aware of patterns of FDG accumulation in tuberculosis in the diagnosing malignancies.

Fluorodeoxyglucose positron emission tomography/computed tomography and magnetic resonance imaging of uterine leiomyosarcomas: 2 cases report.

Uterine leiomyosarcoma is an uncommon malignant neoplasm of smooth muscle origination and is associated with a poor prognosis. We report two cases of uterine leiomyosarcoma that presented with pulmonary metastases. 2-deoxy-2-(¹8F)fluorodeoxyglucose (FDG) positron emission tomography (PET)/computed tomography (CT) was performed to identify the primary carcinoma and found the focus located in the uterus. The follow-up magnetic resonance imaging (MRI) confirmed the diagnosis was uterine leiomyosarcoma.