Preliminary study on MR colonography with air enema in detection of colorectal neoplasms.

BACKGROUND: The few studies on MR colonography with air enema involved feasibility of bowel distention and imaging quality and lacked detection sensitivity of colorectal neoplasms. The purpose of this prospective study was to assess the detection sensitivity of colorectal neoplasms with the three-dimensional Fourier transform fast spoiled gradient-recalled MR colonography with air enema. METHODS: A total of 30 patients scheduled for optical colonoscopy due to rectal bleeding, positive fecal occult blood test results or altered bowel habits were recruited and successfully underwent entire colorectal examinations with three-dimensional Fourier transform fast spoiled gradient-recalled MR colonography and subsequent optical colonoscopy on the same day. Detection sensitivity of colorectal neoplasms with MR colonography was statistically analyzed on a per-neoplasm size basis by using findings from optical colonoscopy and histopathological examinations as the reference standards. RESULTS: Seventy-six neoplasms were detected with optical colonoscopy, consisting of 1 mm-5 mm (n = 11), 6 mm-9 mm (n = 29) and ≥ 10 mm (n = 36) in diameter. Detection sensitivities of 1 mm-5 mm, 6 mm-9 mm, ≥ 10 mm and ≥ 6 mm colorectal neoplasms with MR colonography were 9.1%, 75.9%, 100% and 89.2%, respectively; overall detection sensitivity for all sizes colorectal neoplasms was 77.6%. CONCLUSIONS: Detection sensitivity of three-dimensional Fourier transform fast spoiled gradient-recalled MR colonography with air enema is low for 1 mm-5 mm colorectal neoplasms, but the detection sensitivity is 89.2% for ≥ 6 mm neoplasms, and all ≥ 10 mm neoplasms could be detected.

Influence of applying nitroglycerin in whole-heart free-breathing 3D coronary MR angiography.

OBJECTIVE: The purpose of our study was to assess the impact of sublingual nitroglycerin (NTG) spray on free-breathing 3D whole-heart coronary MR angiography (MRA). SUBJECTS AND METHODS: We compared the timing parameters; measured the lumen diameter of the major coronary arteries; calculated coronary vasodilation, apparent signal-to-noise ratio (SNR), and apparent contrast-to-noise ratio (CNR); and evaluated the image quality on pre- and post-NTG coronary MRA in 15 volunteers. Statistical analysis was performed with p value less than 0.05 considered significant. RESULTS: The mean trigger delay and optimal acquisition window were shortened significantly and the mean scanning time was prolonged statistically after NTG administration. There was no significant alteration in terms of apparent SNR and apparent CNR. The lumen diameters were significantly larger in coronary MRA post-NTG than in that of pre-NTG, with an average 25.35% +/- 6.51% (SD) increase, and the left circumflex coronary artery (LCX) had slightly lower vasodilation in comparison with the right coronary artery. Image quality scores of 53 (39.3%, 53/135) segments were increased and 15 segments (11.1%, 15/135) decreased after NTG administration, and the remaining 67 segments (49.6%, 67/135) were unchanged. CONCLUSION: In general, sublingual NTG is useful for improving visualization of the coronary artery lumen and alleviating the impact of artifact. However, several alterations and disadvantages should be taken into consideration in view of the disturbed assessment of vasodilatory response in the LCX and the impaired quality in a minority of segments after NTG administration. Further studies are needed to evaluate the effect of beta-blockade on eliminating the disadvantages of sublingual NTG.

[Comparative study on clinical and pathological changes of liver fibrosis with diffusion-weighted imaging].

OBJECTIVE: To evaluate the clinical practical value of apparent diffusion coefficient (ADC) measurements based on diffusion-weighted MR imaging (DWI) for quantification of liver fibrosis and inflammation for hepatitis viral infection. METHODS: Diffusion-weighted MRI with parallel imaging was prospectively performed on 85 patients with chronic hepatitis and on 22 healthy volunteers within a single breath-hold using a single-shot spin-echo echo-planar sequence at b values of 100, 300, 500, 800 and 1000 s/mm2 respectively. ADC values of liver were measured with five different b values. The inflammation grades and fibrosis stages were evaluated histologically by biopsy. One-way analysis of variance and Spearman' s rank correlation test were used for statistical analysis. Receiver operating characteristics analysis was used to assess the performance of ADC in predicting the presence of stage > or = 2 and stage > or = 3 hepatic fibrosis, and grade > or = 1 hepatic inflammation. RESULTS: There was moderate negative correlation between hepatic ADC values and fibrosis stage. And the best correlation was obtained for a b value of 800 s/mm2 (r = -0.697, P = 0. 000). At all b values there was a significant decrease in hepatic ADC in patients with stage < or = 1 versus stage > or = 2 fibrosis and stage < or = 2 versus stage > or = 3 fibrosis (P < 0.05). Hepatic ADC was a significant predictor of stage > or = 2 and > or = 3 fibrosis. The areas under the curve were 0.909 vs 0.917, sensitivity 76.6% vs 80.0% and specificity 88.3% vs 91.5% (ADC with a b value of 800 s/mm2, 1.26 x 10(-3) mm2/s or less and 1.19 x 10(-3) mm2/s or less). There was weak to moderate negative correlation between ADCs and inflammation grade. Hepatic ADC was a significant predictor of grade > 1 inflammation with an area under the curve of 0.781, sensitivity of 60.0% and specificity of 86.4% (ADC with a b value of 500 s/mm2, 1.54 x 10(-3) mm2/s or less). CONCLUSION: The DWI measurement of hepatic ADC can be used to quantify liver fibrosis and inflammation. It will be a new approach for early diagnosis and therapeutic follow-up of hepatic fibrosis.

[The value of breath-hold diffusion-weighted imaging in small hepatocellular carcinoma lesion (

OBJECTIVE: To evaluate the added value of single breath-hold diffusion-weighted imaging (DWI) in detection of small HCC lesions (

A study of in vitro and in vivo MR of free-breathing whole-heart 3D coronary angiography using parallel imaging.

To evaluate parallel-imaging methods in free-breathing whole-heart 3D coronary magnetic resonance angiography and assess the navigator techniques and visualization rates of the major coronary arteries. We compared key parameters of the generalized autocalibrating partially parallel acquisition and modified sensitive encoding images in vitro phantom MRI; performed the MRA with GRAPPA parallel imaging in healthy volunteers; compared 1D- and 2D-prospective acquisition correction and analyzed the differences; and evaluated the visualization of major coronary arterial branches. GRAPPA images had higher signal-to-noise ratio and contrast-to-noise ratio and fewer aliasing artifacts. The coronary arteries were adequately visualized in 38 volunteers. 2D-PACE had a higher navigator efficiency, shorter scan time, and gave clearer reconstructed images in comparison with 1D-PACE. GRAPPA images were superior to mSENSE images. Whole-heart 3D coronary MRA along with parallel-imaging technique is a potential clinical method, and 2D-PACE is a better navigation technique than 1D-PACE.

[Comparison of MRI manifestations and histopathologic findings in pancreatic head carcinoma in vivo ex vivo].

OBJECTIVE: To prospectively analyze the correlation of MRI image characteristics with histopathological findings in pancreatic head carcinoma in vivo and ex vivo. METHODS: Sixteen patients with pancreatic head carcinoma were examined by 1.5T MRI. MR sequences included pre-and post-contrast dynamic 2D FLASH T1WI, TSE T2WI + fat suppressed (FS). All fresh specimens were scanned again within an hour after resection during the Whipple procedure, and were then cut into slices along the direction of MRI scan. The MRI image characteristics were compared with gross and histopathologic findings of the specimens. RESULTS: The tumor size ranged from 1.5 cm x 2.0 cm to 4.8 cm x 4.2 cm with a mean value of 3.6 cm x 3.1 cm. The MRI findings in vivo showed hypointensity in 14 lesions and isointensity in 2, and on 2D FLASH T1WI and TSE T2WI, all lesions displayed mixed intensity except 3 lesions with iso-intensity. During post-contrast dynamic pancreatic parenchymal phase, 15 lesions showed mild enhancement and 11 lesions had ring enhancement sign. Nine lesions displayed progressive irregular moderate enhancement during post-contrast dynamic hepatic phase. Four lesions showed enhancement with iso- and hyperintensity in post-contrast dynamic delayed phase. The MRI findings demonstrated that all lesions ex vivo had hypointensity on 2D FLASH T1 WI and mixed intensity on TSE T2WI + FS. Tumor tissues mainly displayed hypointensity, and the area containing tumor and inflammatory tissue showed iso-intensity on 2D FLASH T1WI. On T2WI + FS, the fibrosis proportion displayed hypo or isointensity, while the tumor and chronic inflammatory tissue demonstrated slight hyperintensity, and the zones of mucous degeneration or pancreatic ductal dilatation displayed hyper-intensity. The ring enhancement of tumor was caused by multiple factors and no obvious enhancement within tumor and fibrosis area were observed during post-contrast dynamic pancreatic parenchymal phase. Progressive irregular enhancement originated from desmoplastic reaction within the tumor during post-contrast dynamic hepatic phase and delayed phase, respectively. CONCLUSION: Pancreatic head carcinomas contain various kinds of tissues. MRI can reveal these pathologic characteristics. No obvious hemorrhage and necrosis within the tumor were observed in this series.

Ferucarbotran versus Gd-DTPA-enhanced MR imaging in the detection of focal hepatic lesions.

AIM: To evaluate the efficacy of ferucarbotran-enhanced MR imaging in the detection of focal hepatic lesions compared to plain and Gd-DTPA-enhanced MR imaging. METHODS: Fifty-nine patients with suspected focal hepatic lesions were admitted to the study. Plain MR imaging (FSE T(2)WI with fat suppression and GRE T(1)WI sequences) and Gd-DTPA dynamic enhanced MR of the liver were initially performed followed by ferucarbotran-enhanced MR imaging 48 h later (including GRE T(1)WI, FSE T(2)WI with fat suppression, and GRE T(2)WI sequences). Images were reviewed independently by three observers. Results were correlated with surgery and pathologic examination or reference examination, and sensitivity was statistically calculated for the different MR imaging sequences. RESULTS: Among all confirmed lesions (n = 133), ferucarbotran-enhanced MR imaging revealed 130 lesions on FSE T(2)WI with fat suppression, 115 lesions on dynamic T(1)WI GRE, and 127 lesions on GRE T(2)WI. Pre-contrast MR imaging revealed only 84 lesions on GRE T(1)WI and 106 lesions on FSE T(2)WI with fat suppression, while Gd-DTPA dynamic enhanced GRE T(1)WI revealed 123 lesions. For 44 micro-lesions (< 1.0 cm) in all patients the detection rates were as follows: ferucarbotran-enhanced FSE T(2)WI with fat suppression, 93.2% (41/44); ferucarbotran-enhanced GRE T(2)WI, 88.6% (39/44); Gd-DTPA dynamic-enhanced GRE T(1)WI, 79.5% (35/44); pre-contrast FSE T(2)WI with fat suppression, 54.5% (24/44); and pre-contrast GRE T(1)WI, 34.1% (15/44). In detecting micro-lesions, statistically significant difference was found for Ferucarbotran-enhanced FSE T(2)WI with fat suppression and GRE T(2)WI sequences compared to the other sequences (P < 0.05). CONCLUSION: Ferucarbotran-enhanced FSE T(2)WI with fat suppression and GRE T(2)WI sequences are superior in detecting micro-lesions (< 1 cm) in comparison with plain and Gd-DTPA dynamic-enhanced MR imaging.

[A comparative study of MRI manifestations and pathological changes in hepatocellular carcinoma treated by transcatheter arterial chemoembolization with lipiodol].

OBJECTIVES: To analyze the MRI manifestations and pathological changes of hepatocellular carcinoma (HCC) after transcatheter arterial chemoembolization (TACE) with lipiodol. METHODS: 23 patients with 31 HCC lesions treated by TACE underwent MRI examination within 1 week before their surgical resections. MRI was performed with SE sequence (T1WI and FSE T2WI) and FMPSPGR sequence dynamic multi-phase contrast scans. All resected specimens were cut into 5-10mm thick slices, corresponding to the same plane as that of MRI scans. The specimens were wholly embedded in paraffin, serial sections made and stained with hematoxylin and eosin. The MRI findings were thus compared with the pathology of the specimen sections. RESULTS: (1) MRI findings: In all 31 lesions, the signal intensity of lesions varied and was mostly heterogeneous on SE T1WI and T2WI images. Three lesions were inhomogeneous hyper-intensity and the other 28 lesions were iso- or hypo-intensity on FMPSPGR plain scannings. Twenty-two lesions were enhanced on early-phase dynamic scanning, and no enhancement was found in the other 9 lesions. Partial enhancement was also seen in 6 lesions on delay-phase dynamic scanning. (2) Pathologically, no coagulation necrosis was found in 2 specimens, but 6 lesions showed complete coagulation necrosis and 23 showed various degrees of it. The other pathological changes found included intra-tumoral hemorrhage (n=10), intra-lesional fibrotic septa formation (n=5), capsule-like fibrotic tissue proliferation around the lesions (n=12), inflammatory infiltration (n=28), focal mucoid degeneration (n=2), focal hyaline degeneration (n=2), and lipiodol retention (n=6). (3) Radiological-pathological correlation study: hyper-intense areas on T1WI corresponded to areas of coagulation necrosis with or without hemorrhage and of residual viable tumor; iso- and hypo-intense corresponded to areas of coagulation necrosis or residual viable tumor. Hyper-intense areas on T2WI corresponded to those of residual viable tumor or coagulation necrosis with hemorrhage, and iso-intense areas corresponded to those of coagulation necrosis, small residual viable tumor or intra-lesional fibrotic septa formation, and hypo-intense areas corresponded to those of coagulation necrosis or intra-lesional fibrotic septa formation. Areas of enhancement within the lesions on the early-phase dynamic-contrast images corresponded to areas of residual viable tumors, while areas of no enhancement were those of coagulation necrosis, hemorrhage, intra-lesional fibrotic septa formation or small residual viable tumors. Areas of enhancement on the delay-phase dynamic scanning were those of residual viable tumors or intra-lesional fibrotic septa formation, while no enhancement corresponded to the areas of residual viable tumors, coagulation necrosis, and hemorrhage. Areas of enhancement on the delay-phase dynamic scanning corresponded to those areas of fibrosis tissue or residual viable tumors. Inflammatory infiltration was found in areas of different signal intensity on MRI images. CONCLUSIONS: (1) Different pathological changes in HCCs after TACE are represented by various signal intensities on SE sequence images. The only area of hypo-intensity on T2WI has a specificity in representing coagulation necrosis. (2) FMPSPGR sequence dynamic MRI is superior to SE sequence in demonstrating and determining the necrosis and residual viable tumor. Enhanced areas within the lesions on the early-phase dynamic-contrast images represent residual viable tumors and the enhancement of capsule on early-phase dynamic-contrast images also represent subcapsular residual viable tumors. (3) MRI can demonstrate accurately the areas of necrosis and residual viable HCC tissues after TACE and evaluate the effect of TACE.

Characterization of focal hepatic lesions with SPIO-enhanced MRI.

AIM: To evaluate the value of superparamagnetic iron oxide (SPIO) enhanced MRI in characterizing focal hepatic lesions. METHODS: Forty-three patients (32 men,11 women, mean age 51 years, age range 25-74 years) with previously identified focal hepatic lesions were enrolled into this study. All the patients underwent plain, Gd-DTPA enhanced MRI and the SPIO enhanced MRI 1-7 d later. The surgico-pathologic diagnosis was aestablished in 31 cases and the diagnosis in other 12 cases was made on the basis of clinical findings and biochemical tests. The signal changes of lesions were analyzed and the CNRs of lesion-to-liver were measured before and after SPIO enhancement. The data were analyzed by paired t test. RESULTS: Focal hepatic lesions included primary hepatocellular carcinoma (HCC,n=22), hemangioma (n=5), cyst (n=4), metastases (n=5), cirrhotic nodule (n=4), focal nodular hyperplasia (FNH, n=5) and other miscellaneous lesions (n=6). After SPIO enhancement HCC demonstrated iso- or slight hyperintensity on T1WI and moderate hyperintersity on T2WI, hemangioma showed moderate hyperintensity on T1WI and obvious hyperintensity on T2WI, the SI of cyst had no change either on T1WI or on T2WI, cirrhotic nodules revealed iso-intensity on T2WI, and the SI of FNH decreased significantly on T2WI. No specific manifestations were found in the other 6 miscellaneous lesions after SPIO enhancement. CONCLUSION: SPIO enhanced-MRI can improve the characterization confidence for diagnosis of focal hepatic lesions.

Enhancement patterns of small hepatocellular carcinoma shown by dynamic MRI and CT.

OBJECTIVES: To study prospectively the enhancement features of small hepatocellular carcinoma (SHCC) with multi-phase scanning of dynamic MRI and spiral CT, and discuss the superiority of dynamic MRI to spiral CT. METHODS: Multi-phase dynamic contrast scanning of high field MRI and spiral CT were performed in 53 patients with SHCC. The arterial phase, portal venous phase and delayed phase scanning of spiral CT was done after the pre-contrast scanning of the entire liver. MRI was performed with SE sequence and fast multiplanar spoiled gradient-recalled sequence dynamic multi-phase contrast scanning. RESULTS: Seventy-six lesions were found in all 53 patients. Sixty-nine and 54 of the 76 lesions enhanced obviously in MRI and spiral CT arterial phase scanning respectively. The typical enhancement patterns of SHCC in the arterial phase, portal venous phase and delayed phase scanning of MRI and spiral CT were hyper-hypo-hypointense (dense) and hyper-iso-hypointense (dense). Atypical enhancement patterns were hyper-hyper-hyperintense (dense), hyper-iso-isointense (dense) and hypo-hypo-hypointense (dense). CONCLUSIONS: Both MRI and spiral CT multi-phase dynamic contrast-enhanced scanning could demonstrate the enhancement features of SHCC, and arterial phase scan of MRI was superior to spiral CT in reflecting the hypervascular characterization of SHCC. In addition, MRI was better than spiral CT in characterization of hepatic lesions combined with SE sequence.