CBM drilling technical parameter optimization methodology and software development: a case study of LUAN mining area.

Based on the leakage of the coalbed methane (CBM) drilling engineering practice of Luan mining area in China, the author determines the safe drilling fluid density range for the stable borehole wall based on borehole wall collapse and fracture pressure. Such parameters as the drilling fluid hydraulic parameters (including pump pressure, pump power and displacement, nozzle diameter, bit pressure drop, bit hydraulic horsepower, circulation pressure drop, impact force and jet velocity) and drilling parameters (including weight-on-bit, drilling rotary speed, bit tooth wear) in each borehole section are optimized. Taking the lowest drilling cost as the controlling target, the drilling parameter optimization model is designed and solved by the genetic algorithm. Furthermore, a software named "CBM borehole wall stability parameter design and optimization" characterized by visualization and applicable for drilling formation condition, which can be used to design and optimize the borehole drilling technological parameters, is developed. This program includes such modules as drilling fluid density prediction, drilling technology design, database management, user management and help. The developed software is proven to solve the drilling leakage effectively in the No.67 borehole practice, which can help drilling engineers to optimize CBM drilling technological parameters safely and quickly.

Differentiation of renal oncocytoma and renal clear cell carcinoma using relative CT enhancement ratio.

BACKGROUND: The difference between renal oncocytomas (RO) and renal clear cell carcinomas (RCCs) presents the greatest diagnostic challenge. The aim of this study was to retrospectively determine if RO and RCCs could be differentiated on computed tomography (CT) images on the basis of their enhancement patterns with a new enhancement correcting method. METHODS: Forty-six patients with a solitary renal mass who underwent total or partial nephrectomy were included in this study. Fourteen of those were RO and 32 were RCCs. All patients were examined with contrast-enhanced CT. The pattern and degree of enhancement were evaluated. We selected the area that demonstrated the greatest degree of enhancement of the renal lesion in the corticomedullary nephrographic and excretory phase images. Regions of interest (ROI) were also placed in adjacent normal renal cortex for normalization. We used the values of the normal renal cortex that were measured at the same time as divisors. The ratios of lesion-to-renal cortex enhancement were calculated for all three phases. The Student's t-test and Pearson's Chi-square test were used for statistical analyses. RESULTS: All RCCs masses showed contrast that appeared to be better enhanced than RO on all contrast-enhanced phases of CT imaging, but there was no significant difference in absolute attenuation values between these two diseases (P > 0.05). The ratio of lesion-to-cortex attenuation in the corticomedullary phase showed significantly different values between RO and RCCs. The degree of contrast enhancement in RCCs was equal to or greater than that of the normal renal cortex, but it was less than that of the normal cortex in RO in the corticomedullary phase. The ratio of lesion-to-cortex attenuation in the corticomedullary phase was higher than the cut off value of 1.0 in most RCCs (84%, 27/32) and lower than 1.0 in most RO (93%, 13/14) (P < 0.05). In the nephrographic phase, the ratio of lesion-to-cortex attenuation was higher than that in the corticomedullary phase in most RO (71%, 10/14), showing a prolonged enhancement pattern; and was lower than that in most RCCs (97%, 31/32), showing an early washout pattern (P < 0.05). In the differentiation of RO from RCCs, the sensitivity was 93%, specificity 84%, positive predictive value 72%, negative predictive value 84%, and accuracy for RO was 87, if the ratio of lesion-to-cortex attenuation in a cortex phase was lower than the cutoff value of 1.0. The sensitivity was 71%, specificity was 97%, positive predictive value was 91%, negative predictive value was 91%, and accuracy for RO was 89%, if the ratio of lesion-to-cortex attenuation in nephrographic phase was higher than that in the corticomedullary phase. CONCLUSIONS: The ratios of renal lesion-to-cortex attenuation ratios may be helpful in differentiating RO from RCCs.

The performance of MRI in detecting subarticular bone erosion of sacroiliac joint in patients with spondyloarthropathy: a comparison with X-ray and CT.

OBJECTIVE: To assess the sensitivity and specificity of detecting subarticular bone erosion of sacroiliac (SI) joint in patients with spondyloarthritis (SpA) using MRI three-dimensional water selective balanced steady-state free precession sequence (3D-WS-bSSFP) and T1-weighted (T1W) sequence. MATERIALS AND METHODS: Radiography, CT and MRI of SI joint from 43 SpA patients were retrospectively analyzed. MRI examination sequences include T1W, short tau inversion recovery (STIR) and 3D-WS-bSSFP. Two radiologists, blinded to clinical data, independently determined bone erosion at bilateral sacral and iliac sides of the SI joint on radiography, CT, T1W and 3D-WS-bSSFP respectively. X(2) test was used to compare the sensitivity of detecting bone erosion among different diagnostic methods. RESULTS: Of the 86 sacral and 86 iliac articular surfaces from the 43 cases, radiography, CT, MRI T1W and 3D-WS-bSSFP showed the presence of bone erosion in 40, 74, 50 and 71 articular surfaces respectively. CT and MRI 3D-WS-bSSFP demonstrated similar sensitivity (x(2)=0.11, P=0.74), and both were superior to radiography (x(2)=15.17, P<0.01 and x(2)=12.78, P<0.01, respectively) and T1W (x(2)=7.26, P<0.01 and x(2)=5.62, P<0.05). Using CT diagnosis as the gold standard, the sensitivity and specificity of detecting bone erosion for MRI 3D-WS-bSSFP and T1W sequences were 91.8%, 96.9%, and 60.8%, 94.9% respectively. CONCLUSION: MRI 3D-WS-bSSFP sequence is associated with short scanning time, zero ionizing radiation, high sensitivity and specificity of displaying the subarticular bone erosion of SI joints in patients with SpA. Therefore, it can be considered an alternative to CT.

[MR manifestations and clinical significance of iliotibial band friction syndrome].

OBJECTIVE: To describe the MRI features of Iliotibial band friction syndrome (ITBFS), in order to improve the understanding and diagnosis of ITBFS. METHODS: The MR findings of 16 patients (18 knees )of clinically diagnosis ITBFS were reviewed retrospectively. RESULTS: The MRI features of ITBFS:(1)Ill- defined abnormal signal intensity extended to the lateral femoral epicondyle.(2) Poorly defined abnormal signal intensity presented deep to the ITB adjacent to the lateral femoral epicondyle. (3) Fluid collections medial to the ITB adjacent to the lateral femoral epicondyle. (4) The part of ITB over the lateral femoral epicondyle was thicker. (5) Joint effusion. (6)Other abnormal signs. CONCLUSION: MRI is a relatively good method for detection of ITBFS.

The application of MR imaging in the detection of hip involvement in patients with ankylosing spondylitis.

OBJECTIVE: To investigate the changes in hip MR imaging, evaluate the frequency of hip involvement and compare the value of clinical symptoms, radiographs, and MR imaging in the detection of hip involvement in patients with ankylosing spondylitis (AS). METHODS: Anteroposterior radiographs of the pelvis, MR imaging of the hip and clinical evaluation were undertaken in 58 patients with definite AS. All patients were followed up 3 years. Annual radiographs and clinical evaluation were carried out. The imaging data were independently assessed by two experienced radiologists who were blinded to patient identity and clinical characteristics. Based on the Bath Ankylosing Spondylitis Radiology Hip Index (BASRI-hip) scoring system, BASRI-hip scores ≥ 2 were defined as radiological hip involvement. On MR imaging, both acute and chronic inflammatory changes were considered positive signs for hip involvement. Symptomatic hip involvement was defined as current or past pain or limitation of the hip movement. The statistical analysis was performed using the χ(2) test for comparison of sensitivity among clinical symptoms, radiographs, and MR imaging in the detection of hip involvement and the Student's t-test for comparison of disease duration between with and without hip involvement. A P value <0.05 was considered to be statistically significant. For interpreting MRI and radiographs, the percentage of agreement between the two assessors and the kappa coefficients were calculated. RESULTS: On MR imaging, positive changes were detected in 86 (74.1%) hips among 116 hips in all 58 patients. Joint effusion was observed in 73 (62.9%) hips; 23 out of 27 patients who underwent fat-saturated contrast-enhanced T1-weighted sequences had abnormal synovial enhancement in bilateral hips. The other abnormal MR findings included subchondral bone marrow edema in 35 (30.2%) hips, enthesitis in 22 (19.0%) hips, fatty accumulation of the bone marrow in 28 (24.1%) hips, bone erosive destruction in 32 (27.6%) hips, and joint-space narrowing in 4 (3.4%) hips. Based on the BASRI-hip scoring system, 68, 24, 18, 6 and 0 hips had no, suspicious, mild, moderate or severe damage on conventional radiographs of the pelvis, respectively. Thirty-five hips in 20 patients had current or past pain or limitation. The proportion of hip involvement according to MR imaging, radiographs, and clinical symptoms was 74.1% (86/116), 20.7% (24/116), and 30.2% (35/116), respectively. MR imaging yielded higher values than radiographs and clinical symptoms in the detection of hip involvement in patients with AS (χ(2)=66.45 and 44.93, P <0.05). Interreader reliability for interpretation of findings was acceptable for both MRI and radiographs. During follow-up, radiological hip involvement were found in 10 hips with BASRI-hip scores ≤ 1 at baseline and clinical symptoms appeared in 15 sides of the original asymptomatic hip. On baseline MR imaging, inflammatory changes were seen in all hips which appeared symptoms and/or radiological involvement both at baseline and during follow-up. CONCLUSION: The proportion of hip involvement is much higher than that suggested by radiographic changes and clinical symptoms. MR imaging is superior to conventional radiographs and clinical symptoms in the detection of hip involvement. Joint effusion and synovial enhancement caused by synovitis are the commonest hip findings on MR imaging in patients with AS.

[Diagnostic value of computed tomography in invasive pulmonary fungal infections].

OBJECTIVE: To analyze the computed tomographic (CT) features of invasive pulmonary fungal infections (IPFI) and evaluate the value of CT-guided percutaneous biopsy. METHODS: Seventeen IPFI cases diagnosed by CT-guided percutaneous biopsy were recruited. The distribution, extent, density and size of IPFI were analyzed in correlation with the final diagnosis retrospectively. And the relationship with the causative factor of mycosis was also assessed. RESULTS: (1) Candida albicans (n = 7) and cryptococcosis & aspergillus (n = 5) were identified. (2) It showed segmental on lobar consolidation within lung field (n = 6), mixture of patterns and nodule (n = 4) and mass (n = 7). (3) The overall diagnostic accuracy of fiberoptic bronchoscopy examination was 35.3%. (4) The incidence of complicated pneumothorax was 11.8% (2/17). These cases were self-limited without any special treatment. CONCLUSION: The CT findings of PFI are too complex to be easily distinguished from other diseases. And the CT-guided percutaneous is a safe and effective procedure.

[Avascular necrosis of the femoral head:correlation of imaging and pathological findings].

OBJECTIVE: To investigate the relationship between imaging and pathological findings of avascular necrotic of the femoral head (ANFH). METHODS: A comparison among of conventional radiography, computerized tomography (CT), magnetic resonance imaging (MRI), gross section and pathological examinations was performed in 20 femoral heads in 15 patients undergoing total hip replacement for established ANFH. RESULTS: ANFH involved the anterosuperior aspect of femoral head in all hips. Necrotic femoral heads consisted of cartilage, necrotic area, reactive repaired area and extralesional area. The reactive repaired area surrounded necrotic area. Imaging findings: 1) on conventional radiography and CT, as compared with the extralesional area, the necrotic area appeared to be of an equal density (11), a lower density (7) and a higher density (2) On MRI, the necrotic areas revealed adipose intensity (3), blood like intensity (1), aquatic intensity (2), fibrous intensity (9) and non-homogeneous intensity (5); 2) the reactive repaired area separated the necrotic and extralesional areas. Both on plain radiography and CT, the reactive repaired area showed a sclerotic band surrounding the necrotic area and a hypo-density inner line adjacent to sclerotic band was seen in 11 femoral heads on CT and 7 on conventional radiography. A band of low signal in the proliferative zone was seen on MRI in all hips and a rim of high signal intensity inside the low-signal margin (double-line sign) was seen in 3 hips on T2W images. CONCLUSION: Conventional radiography, CT and MRI can display the grossly discernable necrotic, reactive repaired and extralesional areas accurately. Characteristic imaging findings are observed in the reactive repaired area.

[Study of comparing the multiple MR sequenc in the articular cartilage of knee joint].

OBJECTIVE: To investigate the value of various MR imaging sequences for the assessment of articular cartilage and to determine the most optional sequence. METHODS: MR sagittal scanning of knee joints were performed in nine fresh bovine models. MR scan sequences consisted of TSE-T(1)WI, TSE-T(2)WI, TSE-PDWI, 3D-FFE-T(1)WI, 3D-BFFE, TSE-T(1)WI-SPIR, TSE-T(2)WI-SPIR, TSE-PDWI-SPIR, 3D-FFE-SPIR, 3D-FFE-WATS, 3D-FFE-MTC, 3D-BFFE-WATS. The signal noise ratio (SNR) and contrast noise ratio (CNR) between cartilage and adjacent tissue were calculated and compared. The knees of fifteen healthy volunteers were imaged with the selective MR sequences and the SNR, CNR and their efficiency were calculated and analyzed statistically. RESULTS: In bovine knee models, the cartilage SNR was higher in the sequences which attached SPIR, WATS and MTC than that of without these techniques. There was a statistically significant difference. The CNR between cartilage and adjacent tissue was also higher in the former. In healthy volunteers, the cartilage SNR was better in 3D-FFE-SPIR, 3D-FFE-WATS, 3D-BFFE-WATS. CNR between cartilage and bone, marrow, muscle, fat were better in 3D-FFE-SPIR, 3D-FFE-WATS, 3D-BFFE-WATS; CNR between cartilage and liquid was better in 3D-FFE-WATS, TSE-T2WI-SPIR, TSE-PDWI-SPIR; CNR between cartilage and meniscus, ligament was better in 3D-FFE-SPIR, 3D-BFFE-WATS, TSE-PDWI-SPIR. The SNR and CNR efficiency were higher in 3D-FFE-WATS, 3D-BFFE-WATS, 3D-FFE-SPIR. There was a statistical difference between these sequences and others (P < 0.01). The cartilage SNR and CNR between cartilage and bone, muscle of 3D-FFE-SPIR weren't significantly higher than that of 3D-FFE-WATS (P > 0.05); CNR between cartilage and liquid, marrow, fat were higher in 3D-FFE-WATS and significantly different than that of 3D-FFE-SPIR (P < 0.01). CONCLUSION: Articular cartilage SNR and CNR between cartilage and its surrounding tissue are higher in sequences attached SPIR, WATS, so fat suppress technique should routinely be used in clinical cartilage examination. WATS has high scan speed and suppress the fat signal evenly, so it can substitute SPIR. 3D-FFE-WATS is one of the most sensitive sequences in showing cartilage shape and detecting its injury. The cartilage SNR, the CNR between cartilage and adjacent tissue and their efficiency are high in 3D-BFFE-WATS and it can be used in the clinical examination.

[Application of computed tomography guided percutaneous fine-needle aspiration biopsy in examination of pancreas and Vater's ampulla].

OBJECTIVE: To evaluate the effects of computed tomography (CT) guided percutaneous fine-needle aspiration biopsy (FANB) in examination of pancreas and Vater's ampulla. METHODS: One hundred and six patients, 71 males and 35 females, aged 21 approximately 74, with lesions located in the pancreas and Vater's ampulla, 1.5 approximately 5 cm in size (< 3 cm in 32 cases and >or= 3 cm in 74 cases), underwent CT guided percutaneous FANB with 22-gauge needle (in 84 cases) or 20-gauge needle (in 22 cases) by anterior approach. The biopsy sites included the head of pancreas and ampulla (n = 70), body of pancreas (n = 24), and tail of pancreas (n = 12). The key points of FANB included selection of appropriate cross-section, entry of needle, and multiple insertion in fan-like fashion with fast puncture and aspiration. Pathological examination was done to all biopsy specimens. RESULTS: All lesions were safely accessed with an accuracy rate of 100% and without major complications. Pathological examination showed that 83 lesions were malignant, 5 of which were confirmed as false-positive, and 20 lesions were benign 2 of which were confirmed as false-negative, and 3 lesions were true-negative. The accuracy rates of diagnosis of malignant lesions and of diagnosis of benign lesion were 94% and 90% respectively (P > 0.05). The accuracy rate of diagnosis was 96% for the lesions >or= 3 cm was 96% and 88% for the lesions < 3 cm (P > 0.05). The accuracy rates of diagnosis were 93%, 92%, and 100% for the lesions located in the head of pancreas and ampulla of Vater, body of pancreas, and tail of pancreas (P > 0.05). CONCLUSION: CT guided percutaneous FANB is a safe and effective method for the diagnosis and differential diagnosis of lesions in the pancreas.

[Calculation of articular surface area of osteonecrosis and its application in predicting collapse of the femoral head].

OBJECTIVE: To explore the program for calculating the necrotic articular surface area (NASA) and the ratio of NASA to whole articular surface area (WASA) of osteonecrosis of the femoral head (ONFH), to verify the accuracy of this calculation and to predict the collapse of the femoral head clinically using this program. METHODS: From June 2001 to June 2003, The specimens of the necrotic femoral head from eight patients (13 hips) were obtained by total hip arthroplasty. The magnetic resonance imaging (MRI) was taken in all patients before operation. According to a series of T1-weight pictures, the NASA and the ratio of NASA to WASA were calculated by designing program. The specimens of the necrotic femoral head were sawed into lays similar to MRI pictures using the coordinate paper stick on the auricular surface, the data processing were done by analytic instrument for pictures. The data of both were analyzed statistically by software SPSS 10.0 edition. The NASA and the ratio of NASA to WASA were calculated on MRI in ARCO Stage I, II 16 patients (25 hips) with non-operation. Follow-up was done to the patients with collapse of the femoral head and to the patients with no collapse for at least 24 months. The data were compared in collapse group and non-collapse group. RESULTS: There were no significant differences between MRI pictures calculation and specimens measurement (NASA: 0. 412, ratio of NASA to WASA: 0.812, P>0.05). Of the 25 hips followed up, collapse occurred in 17 hips. NASA was 31.06+/-8.10 cm2, (95% CI. 26.58 to 35.55), the ratio of NASA to WASA was 58.91%+/-15.11%, (95% CI: 51.14 to 66. 68). No collapse appeared in 8 hips. NASA was 14.16+/-9.32 cm2 (95% CI: 6.04 to 21. 95), the ratio of NASA to WASA was 29.48%+/-19.76% (95% CI: 12.97 to 45.99). The ratio in the patients with collapse was beyond 33%. CONCLUSION: The NASA and the ratio of NASA to WASA in patients with ONFH can be accurately calculated with the MRI pictures. The possibility of collapse can be predicted by this method. As it is complicated in operation, improvement should be made in order to put it into clinical use.

[Vascularized iliac bone grafting for avascular necrosis of the femoral head].

OBJECTIVE: To evaluate the indications for vascularized iliac bone grafting in the treatment of osteonecrosis of the femoral head and operative results. METHODS: From October 1993 to August 2000, Twenty-six hips of 18 patients with osteonecrosis of the femoral head underwent vascularized iliac bone grafting. Clinical evaluation was made according to Harris Hip Score and ARCO staging system. RESULTS: Twenty-three hips of 16 patients were followed up for 31.5 months (6 - 74 months) on average. The mean Harris hip score was 76 patients (mean 61.7). Thirteen hips (medial 8 hips, central 3 hips, lateral 2 hips) were graded > 80 points by Harris hip score were. The incidence of radiographic collapse 20% was (medial), 40% (central) and 75% (lateral) respectively. CONCLUSIONS: Vascularized iliac bone grafting is effective for the treatment of osteonecrosis of the femoral head in short and middle term. We recommend this procedure for the patients with ONFH in ARCO stage I, stage IIA, IIB medial and central, and stage IIC medial.

[CT-guided percutaneous transthoracic aspiration biopsy of chest lesions: factors influencing the diagnostic accuracy].

OBJECTIVE: To investigate the factors influencing the diagnostic accuracy of CT-guided percutaneous transthoracic aspiration biopsy of chest lesions. METHODS: Data of pathology and clinical follow-up of 224 patients who had undergone CT-guided percutaneous transthoracic biopsy were collected. Univariate analysis and multivariate stepwise Logistic regression analysis were made to study the influence of the patient-related factors (sex, age, and presence of emphysema), lesion-related factors (histology, size, location, depth, and presence of cavity discovered by CT), and procedure factor (posture of patient during operation) on the diagnostic accuracy of CT-guided biopsy. RESULTS: (1) One hundred and sixty-five lesions were diagnosed as malignant and 79 lesions as benign. The accuracy rate of CT-guided biopsy was 82.4% (201/244). Univariate analysis showed that the diagnostic accuracy rates of CT-guided biopsy for malignant and benign lesions were 88.5% and 69.6% respectively (chi(2) = 13.096, P < 0.01). The mean diameters of the lesions with correct diagnosis and of those misdiagnosed were 4.0 cm +/- 1.8 cm and 3.1 cm +/- 1.4 cm respectively (F = 8.805, P < 0.01). (2) Multivariate stepwise Logistic regression analysis showed that among the various factors only histology (regression coefficient = 0.320, Wald chi(2) = 7.126, P < 0.01) and size (regression coefficient = 1.114, Wald chi(2) = 4.951, P < 0.05) were significantly associated with diagnostic accuracy. CONCLUSION: Histology and size of lesion are the determining factors for diagnostic accuracy of CT-guided transcutaneous thoracic needle aspiration biopsy.