Value of radiomics-based automatic grading of muscle edema in polymyositis/dermatomyositis based on MRI fat-suppressed T2-weighted images.

BACKGROUND: The precise and objective assessment of thigh muscle edema is pivotal in diagnosing and monitoring the treatment of dermatomyositis (DM) and polymyositis (PM). PURPOSE: Radiomic features are extracted from fat-suppressed (FS) T2-weighted (T2W) magnetic resonance imaging (MRI) of thigh muscles to enable automatic grading of muscle edema in cases of polymyositis and dermatomyositis. MATERIAL AND METHODS: A total of 241 MR images were analyzed and classified into five levels using the Stramare criteria. The correlation between muscle edema grading and T2-mapping values was assessed using Spearman's correlation. The dataset was divided into a 7:3 ratio of training (168 samples) and testing (73 samples). Thigh muscle boundaries in FS T2W images were manually delineated with 3D-Slicer. Radiomics features were extracted using Python 3.7, applying Z-score normalization, Pearson correlation analysis, and recursive feature elimination for reduction. A Naive Bayes classifier was trained, and diagnostic performance was evaluated using receiver operating characteristic (ROC) curves and comparing sensitivity and specificity with senior doctors. RESULTS: A total of 1198 radiomics parameters were extracted and reduced to 18 features for Naive Bayes modeling. In the testing set, the model achieved an area under the ROC curve of 0.97, sensitivity of 0.85, specificity of 0.98, and accuracy of 0.91. The Naive Bayes classifier demonstrated grading performance comparable to senior doctors. A significant correlation (r = 0.82, P <0.05) was observed between Stramare edema grading and T2-mapping values. CONCLUSION: The Naive Bayes model, utilizing radiomics features extracted from thigh FS T2W images, accurately assesses the severity of muscle edema in cases of PM/DM.

Ultra-short echo time MR imaging in assessing cartilage endplate damage and relationship between its lesion and disc degeneration for chronic low back pain patients.

OBJECTIVE: To investigate the feasibility of ultra-short echo time (UTE) magnetic resonance imaging (MRI) in the assessment of cartilage endplate (CEP) damage and further evaluate the relationship between total endplate score (TEPS) and lumbar intervertebral disc (IVD) degeneration for chronic low back pain patients. MATERIALS AND METHODS: IVD were measured in 35 patients using UTE imaging at 3T MR. Subtracted UTE images between short and long TEs were obtained to depict anatomy of CEP. The signal-to-noise ratio (SNR) and contrast-to-noise ratio (CNR) were calculated to assess the image quality quantitatively. A new grading criterion for endplate damage evaluation was developed based on Rajasekaran.S grading system in this study. Two radiologists were employed to evaluate CEP and bony vertebral endplates (VEP) using this new grading criterion and assess TEPS, independently. Cohen's kappa analysis was applied to evaluate the inter-observer agreement of endplate damage assessment between two radiologists, and the Kendall's TAU-B analysis was employed to determine the relationship between TEPS and IVD degeneration evaluated with Pfirrmann grading. RESULTS: Well structural CEP was depicted on subtracted UTE images and confirmed by high SNR (33.06±2.92) and CNR values (9.4±2.08). Qualified subtracted UTE images were used by two radiologists to evaluate the degree of CEP and VEP damage. Excellent inter-observer agreement was confirmed by high value in Cohen's kappa test (0.839, P < 0.001). Ensured by this, 138 endplates from 69 IVDs of 35 patients were classified into six grades based on the new grading criterion and TEPS of each endplate was calculated. In addition, the degeneration degree of IVDs were classified into five grades. Finally, using Kendall's TAU-B analysis, significant relationship was obtained between endplate damage related TEPS and IVD degeneration (r = 0.864, P < 0.001). CONCLUSION: Ensured by high image quality, UTE imaging might be considered an effective tool to assess CEP damage. Additionally, further calculated TEPS has shown strong positive association with IVD degeneration, suggesting that the severity of endplate damage is highly linked with the degree of IVD degeneration.

A low-grade malignant soft tissue tumor with S100 and CD34 co-expression showing novel CDC42SE2-BRAF fusion with distinct features.

Recently, a novel group of spindle cell tumors defined by S100 and CD34 co-expression harboring recurrent fusions involving RET, RAF1, BRAF, and NTRK1/2 gene has been identified. Morphologically, they are characterized by monomorphic neoplasm cells, "patternless" growth pattern, stromal, and perivascular hyalinization, lacked necrosis. We reported a 52-year-old Chinese female patient with a S100 and CD34 co-expression sarcoma presenting in the right proximal forearm. The forearm mass initially emerged 19 months ago when it was misdiagnosed as a solitary fibrous tumor and was surgically removed without further treatment. Microscopically, the primary and the recurred tumors share the same features, resembling the morphology of the recently characterized group. Nevertheless, some distinct features, such as predominantly epithelioid tumor cells and focally staghorn vessels, were also present in our case. Genomic profiling with clinical next-generation sequencing was performed and revealed CDC42SE2-BRAF gene fusion, MET amplification, and CDKN2A/B deletion. Both FISH and nested RT-PCR were performed to confirm the gene fusion. The patient was treated with crizotinib for two cycles but showed no obvious benefit. The presented case adds to the spectrum of the novel, characterized solid tumors, and provides suggestions for emerging therapeutic strategies for precision medicine involving targeted kinase inhibitors.

Prevalence of radiographic parameters on CT associated with femoroacetabular impingement in a Chinese asymptomatic population.

BACKGROUND: Imaging evaluation of femoroacetabular impingement (FAI) plays a major role in early diagnosis and treatment, preventing irreversible degenerative changes in hip joints. PURPOSE: To investigate the anatomical parameters associated with FAI in a Chinese asymptomatic population by computed tomography (CT) and to evaluate the prevalence of the radiographic features of cam and pincer types in Chinese patients. MATERIAL AND METHODS: We reviewed the CT images of 470 hips in 235 Chinese patients who underwent abdominal and pelvic CT scans for reasons unrelated to hip symptoms at our hospital between February and October 2017. The following measurements were made on each hip joint: acetabular version angle (AV); anterior acetabular sector angle (AASA); posterior acetabular sector angle (PASA); the lateral center edge angle (LCE); the alpha angle (AA); and femoral head-neck offset (FHNO). RESULTS: Significant differences in all parameters were seen between men and women. Young men and elderly women showed more retroversion in our study. LCE, AA, and FHNO were all larger in men than women. The data showed 25% of female joints and 34.5% of male joints had at least one predisposing factor for FAI using measurement parameters by CT images in Chinese asymptomatic patients, and the prevalence of pincer lesion (19.1%) was larger than cam lesion (9.1%). CONCLUSION: Morphological features associated with FAI are also present in Chinese asymptomatic patients. The threshold values for abnormal parameters should be reconsidered based on gender, age, and other factors in order to improve the accuracy of diagnosis.

Analysis of risk factors causing short-term cement leakages and long-term complications after percutaneous kyphoplasty for osteoporotic vertebral compression fractures.

Background Percutaneous kyphoplasty (PKP) is a common treatment modality for painful osteoporotic vertebral compression fractures (OVCFs). Pre- and postoperative identification of risk factors for cement leakage and follow-up complications would therefore be helpful but has not been systematically investigated. Purpose To evaluate pre- and postoperative risk factors for the occurrence of short-term cement leakages and long-term complications after PKP for OVCFs. Material and Methods A total of 283 vertebrae with PKP in 239 patients were investigated. Possible risk factors causing cement leakage and complications during follow-up periods were retrospectively assessed using multivariate analysis. Cement leakage in general, three fundamental leakage types, and complications during follow-up period were directly identified through postoperative computed tomography (CT). Results Generally, the presence of cortical disruption ( P = 0.001), large volume of cement ( P = 0.012), and low bone mineral density (BMD) ( P = 0.002) were three strong predictors for cement leakage. While the presence of intravertebral cleft and Schmorl nodes ( P = 0.045 and 0.025, respectively) were respectively identified as additional risk factors for paravertebral and intradiscal subtype of cortical (C-type) leakages. In terms of follow-up complications, occurrence of cortical leakage was a strong risk factor both for new VCFs ( P = 0.043) and for recompression ( P = 0.004). Conclusion The presence of cortical disruption, large volume of cement, and low BMD of treated level are general but strong predictors for cement leakage. The presence of intravertebral cleft and Schmorl nodes are additional risk factors for cortical leakage. During follow-up, the occurrence of C-type leakage is a strong risk factor, for both new VCFs and recompression.

Radiomics approach to distinguish between benign and malignant soft tissue tumors on magnetic resonance imaging.

Objective: To build a radiomics signature based on MRI images and evaluate its capability for preoperatively identifying the benign and malignant Soft tissue neoplasms (STTs). Materials and methods: 193 patients (99 malignant STTs and 94 benign STTs) were at random segmented into a training cohort (69 malignant STTs and 65 benign STTs) and a validation cohort (30 malignant STTs and 29 benign STTs) with a portion of 7:3. Radiomics features were extracted from T2 with fat saturation and T1 with fat saturation and gadolinium contrast images. Radiomics signature was developed by the least absolute shrinkage and selection operator (LASSO) logistic regression model. The receiver that operated characteristics curve (ROC) analysis was used to assess radiomics signature's prediction performance. Inner validation was performed on an autonomous cohort that contained 40 patients. Results: A radiomics was developed by a total of 16 radiomics features (5 original shape features and 11 were wavelet features) achieved favorable predictive efficacy. Malignant STTs showed higher radiomics score than benign STTs in both training cohort and validation cohort. A good prediction performance was shown by the radiomics signature in both training cohorts and validation cohorts. The training cohorts and validation cohorts had an area under curves (AUCs) of 0.885 and 0.841, respectively. Conclusions: A radiomics signature based on MRI images can be a trustworthy imaging biomarker for identification of the benign and malignant STTs, which could help guide treatment strategies.

Quantitative Evaluation of Intraspinal Lumbar Disc Herniation-related Lumbosacral Radiculopathy Before and After Percutaneous Transforaminal Endoscopic Discectomy Using Diffusion Tensor Imaging.

STUDY DESIGN: A prospective study. OBJECTIVE: The aim of this study was to investigate the relationship between diffusion tensor imaging (DTI) derived parameters of compressed nerve roots at subregions and the corresponding clinical symptoms to evaluate the patients with intraspinal lumbar disc herniation (LDH)-related lumbosacral radiculopathy pre- and postoperatively. SUMMARY OF BACKGROUND DATA: It is crucial to explore whether magnetic resonanve imaging (MRI) can quantitatively evaluate intraspinal LDH-related lumbosacral radiculopathy before and after surgery. METHODS: In all, 66 patients underwent MRI scans and Clinical assessment before and after percutaneous transforaminal endoscopic discectomy (PTED). Pre- and postoperative findings of the related lumbar disk and nerve tractography were compared with two-way contingency table analysis. The embedded paired t test toolbox was applied to respectively compare the fractional anisotropy (FA) and apparent diffusion coefficient (ADC) values of nerves at the symptomatic and asymptomatic sides in three subregions pre- and postoperatively. The correlation of clinical Japanese Orthopedic Association (JOA) scores and FA/ADC values of nerves at three sub-regions was analyzed by stepwise multiple linear regression analysis. RESULTS: The postoperative FA values were significantly higher than the corresponding preoperative values (P < 0.001), while comparable ADC values were found. Using tractography, a notable improvement of compressed nerve was revealed after surgery (61 cases, 92.4%). Additionally, multiple linear regression analysis identified significant associations between JOA scores and FA values of the compressed nerves with the greatest effect at the proximal region. CONCLUSION: The FA values at subarticular zone can reflect the microstructural changes of the corresponding compressed nerves and well associate with clinical symptoms. Therefore, the DTI parameter FA can be considered an effective tool in clinic to quantitatively evaluate intraspinal LDH-related lumbosacral radiculopathy before and after PTED surgery.Level of Evidence: 3.

A quantitative and clinical evaluation of nerve roots in lumbosacral radiculopathy using diffusion tensor imaging.

PURPOSE: This study aimed to investigate the relationship between the fractional anisotropy (FA) values of compressed nerves derived in diffusion tensor imaging (DTI) and the corresponding clinical symptoms for quantitative and clinical evaluation in patients with lumbosacral radiculopathy. METHODS: Thirty-six patients and ten volunteers participated in the study and measured with DTI. The resultant FA values for L5-S1 lumbar nerve roots were calculated at three sub-regions. Additionally, the DTI relevant tractography was also performed on L4-S1 nerve roots. Clinical symptoms were performed by Japanese Orthopedic Association (JOA) scoring for each patient and volunteer. RESULTS: The FA values of the nerves at the symptomatic side were significantly lower than those at the asymptomatic side (p < 0.001). Diffusion tensor tractography distinctly showed abnormalities in the symptomatic nerve tracts. There was a significant correlation between JOA scores and the FA values of the compressed nerves at middle and distal sub-regions (p < 0.005). CONCLUSION: The clinical symptoms associated robustly with the DTI derived FA values of the compressed nerves in patients with lumbosacral radiculopathy. Therefore, the FA values can be a potential clinical tool to evaluate the nerve roots in lumbosacral radiculopathy quantitatively.

Dynamic contrast-enhanced magnetic resonance imaging in denervated skeletal muscle: Experimental study in rabbits.

PURPOSE: To investigate the value of dynamic contrast-enhanced (DCE) magnetic resonance imaging (MRI) for evaluating denervated skeletal muscle in rabbits. MATERIALS AND METHODS: 24 male rabbits were randomly divided into an irreversible neurotmesis group and a control group. In the experimental group, the sciatic nerves of rabbits were transected for irreversible neurotmesis model. A sham operation was performed in the control group. MRI of rabbit lower legs was performed before nerve surgery and 1 day, 3 days, 5 days, 1 week, 2 weeks, 3 weeks, 4 weeks, 6 weeks, 8 weeks, 10 weeks, and 12 weeks after surgery. RESULTS: Signal intensity changes were seen in the left gastrocnemius muscle on the T2-weighted images. DCE-MRI derived parameters (Ktrans, Kep, and Vp) were measured in vivo. In the irreversible neurotmesis group, T2-weighted images showed increased signal intensity in the left gastrocnemius muscle. Ktrans, Vp values changes occur as early as 1 day after denervation, and increased gradually until 4 weeks after surgery. There are significant increases in both Ktrans and Vp values compared with those in the control group after surgery (P < 0.05). Kep values show no significant difference between the irreversible neurotmesis group and the control group. CONCLUSION: DCE-MRI hold the promise of an early and sensitive diagnosis of denervated skeletal muscle.

Modic changes in lumbar spine: prevalence and distribution patterns of end plate oedema and end plate sclerosis.

OBJECTIVE: The purpose of this study is to evaluate the distribution of end plate oedema in different types of Modic change especially in mixed type and to analyze the presence of end plate sclerosis in various types of Modic change. MATERIALS AND METHODS: 276 patients with low back pain were scanned with 1.5-T MRI. Three radiologists assessed the MR images by T1 weighted, T2 weighted and fat-saturation T2 weighted sequences and classified them according to the Modic changes. Pure oedematous end plate signal changes were classified as Modic Type I; pure fatty end plate changes were classified as Modic Type II; and pure sclerotic end plate changes as Modic Type III. A mixed feature of both Types I and II with predominant oedematous signal change is classified as Modic I-II, and a mixture of Types I and II with predominant fatty change is classified as Modic II-I. Thus, the mixed types can further be subdivided into seven subtypes: Types I-II, Types II-I, Types I-III, Types III-I, Types II-III, Types III-II and Types I-III. During the same period, 52 of 276 patients who underwent CT and MRI were retrospectively reviewed to determine end plate sclerosis. RESULTS: (1) End plate oedema: of the 2760 end plates (276 patients) examined, 302 end plates showed Modic changes, of which 82 end plates showed mixed Modic changes. The mixed Modic changes contain 92.7% of oedematous changes. The mixed types especially Types I-II and Types II-I made up the majority of end plate oedematous changes. (2) End plate sclerosis: 52 of 276 patients were examined by both MRI and CT. Of the 520 end plates, 93 end plates showed Modic changes, of which 34 end plates have shown sclerotic changes in CT images. 11.8% of 34 end plates have shown Modic Type I, 20.6% of 34 end plates have shown Modic Type II, 2.9% of 34 end plates have shown Modic Type III and 64.7% of 34 end plates have shown mixed Modic type. CONCLUSION: End plate oedema makes up the majority of mixed types especially Types I-II and Types II-I. The end plate sclerosis on CT images may not just mean Modic Type III but does exist in all types of Modic changes, especially in mixed Modic types, and may reflect vertebral body mineralization rather than change in the bone marrow. ADVANCES IN KNOWLEDGE: End plate oedema and end plate sclerosis are present in a large proportion of mixed types.

Apparent diffusion coefficient measurements with diffusion-weighted imaging for differential diagnosis of soft-tissue tumor.

OBJECTIVES: To evaluate the diagnostic potential of apparent diffusion coefficient (ADC) values of diffusion-weighted imaging (DWI) in distinguishing malignant and benign soft-tissue tumors. MATERIALS AND METHODS: Published studies were retrieved through comprehensive search in various computerized databases. High-quality studies relevant to ADC values of DWI in differential diagnosis of soft-tissue tumors were screened using our stringent inclusion and exclusion criteria for this meta-analysis. The standard mean difference with 95% confidence interval (95% CI) was estimated. Statistical analyses were performed using the STATA statistical software (Stata Co., College Station, TX, USA). RESULTS: Thirteen cohort studies were finally included, and these studies provided the required information on the diagnostic value of diffusion magnetic resonance imaging in soft-tissue tumors. The 13 studies contained a combined total of 344 malignant soft tumors and 315 benign soft tumors. The results of our meta-analysis revealed that mean ADC value in patients with malignant soft-tissue tumor decreased significantly in comparison with the ADC values obtained in patients with benign soft-tissue tumor (P < 0.001). Country-stratified analysis suggested that ADC value might play a predictive role in the differential diagnosis of soft-tissue tumors in China (P = 0.007), Egypt (P < 0.001), Germany (P = 0.001), Japan (P = 0.049), and The Netherlands (P < 0.001). CONCLUSION: Our results provide strong evidence that patients diagnosed with malignant soft-tissue tumors have low ADC values of DWI compared to those with benign soft-tissue tumors. Therefore, ADC measurements with DWI may be reliable in differential diagnosis of soft-tissue tumors.

Evaluation of MR issues for the latest standard brands of orthopedic metal implants: plates and screws.

PURPOSE: The study was performed to evaluate magnetic resonance (MR) issues for the latest standard brands of plates and screws used in orthopedic surgery at a 1.5-T MR system, including the safety and metallic artifacts. METHODS: The plates and screws (made of titanium alloy and stainless steel materials, according to the latest standard brands) were assessed for displacement in degrees, MRI-related heating and artifacts at a 1.5-T MR system. The displacement in degrees of the plates and screws was evaluated on an angel-measurement instrument at the entrance of the MR scanner. The MRI-related heating was assessed on a swine leg fixed with a plate by using a "worst-case" pulse sequence. A rectangular water phantom was designed to evaluate metallic artifacts of a screw on different sequences (T1/T2-weighted FSE, STIR, T2-FSE fat saturation, GRE, DWI) and then artifacts were evaluated on T2-weighted FSE sequence by modifying the scanning parameters including field of view (FOV), echo train length (ETL) and bandwidth to identify the influence of parameters on metallic artifacts. 15 volunteers with internal vertebral fixation (titanium alloy materials) were scanned with MR using axial and sagittal T2-FSE, sagittal T2-FSE fat suppression and STIR with conventional and optimized parameters, respectively. Then all images were graded by two experienced radiologists having the experience of more than 7 years under double-blind studies that is neither of them knew which was conventional parameter group and optimized parameter group. RESULTS: The average deflection angle of titanium alloy and stainless steel implants were 4.3° and 7.7°, respectively, (less than 45°) which indicated that the magnetically induced force was less than the weight of the object. The deflection angle of the titanium alloy implants was less than the stainless steel one (t=9.69, P<0.001). The average temperature changes of titanium alloy before and after the scan was 0.48°C and stainless steel implants was 0.74°C, respectively, with the background temperature changes of 0.24°C. The water phantom test indicated that the DWI sequence produced largest artifacts, while FSE pulse sequence produced smallest artifacts. And T2-weighted FSE fat saturation sequence produced larger artifacts than STIR sequence. The influence of the scanning parameters on metallic artifacts was verified that metallic artifacts increased with longer echo train length and bigger FOV, while decreased with larger bandwidth. The interreader agreement was good or excellent for each set of images graded with Cohen's Kappa statistic. Image grading of axial and sagittal T2-FSE with optimized parameters were significantly superior to that with conventional parameters (grade, 3.3±0.5 vs 2.7±0.6, P=0.003; 3.2±0.4 vs 1.9±0.7, P=0.001) and image of STIR sequence received a better grade than T2-FSE FS sequence (grade, 3.4±0.5 vs 1.7±0.6, P<0.001). CONCLUSIONS: The latest standard plates and screws used in orthopedic surgery do not pose an additional hazard or risk to patients undergoing MR imaging at 1.5-T or less. Though artifacts caused by them cannot be ignored because of their relatively large size, it is possible to be minimized by choosing appropriate pulse sequences and optimizing scanning parameters, such as FSE and STIR sequence with large bandwidth, small FOV and appropriate echo train length.

Diffusion tensor imaging with quantitative evaluation and fiber tractography of lumbar nerve roots in sciatica.

OBJECTIVE: To quantitatively evaluate nerve roots by measuring fractional anisotropy (FA) values in healthy volunteers and sciatica patients, visualize nerve roots by tractography, and compare the diagnostic efficacy between conventional magnetic resonance imaging (MRI) and DTI. MATERIALS AND METHODS: Seventy-five sciatica patients and thirty-six healthy volunteers underwent MR imaging using DTI. FA values for L5-S1 lumbar nerve roots were calculated at three levels from DTI images. Tractography was performed on L3-S1 nerve roots. ROC analysis was performed for FA values. RESULTS: The lumbar nerve roots were visualized and FA values were calculated in all subjects. FA values decreased in compressed nerve roots and declined from proximal to distal along the compressed nerve tracts. Mean FA values were more sensitive and specific than MR imaging for differentiating compressed nerve roots, especially in the far lateral zone at distal nerves. CONCLUSIONS: DTI can quantitatively evaluate compressed nerve roots, and DTT enables visualization of abnormal nerve tracts, providing vivid anatomic information and localization of probable nerve compression. DTI has great potential utility for evaluating lumbar nerve compression in sciatica.

Morphological MRI and T2 mapping of cartilage repair tissue after mosaicplasty with tissue-engineered cartilage in a pig model.

The aim of this study was to evaluate the efficacy of mosaicplasty with tissue-engineered cartilage for the treatment of osteochondral defects in a pig model with advanced MR technique. Eight adolescent miniature pigs were used. The right knee underwent mosaicplasty with tissue-engineered cartilage for treatment of focal osteochondral defects, while the left knee was repaired via single mosaicplasty as controls. At 6, 12, 18 and 26 weeks after surgery, repair tissue was evaluated by magnetic resonance imaging (MRI) with the cartilage repair tissue (MOCART) scoring system and T2 mapping. Then, the results of MRI for 26 weeks were compared with findings of macroscopic and histologic studies. The MOCART scores showed that the repaired tissue of the tissue-engineered cartilage group was statistically better than that of controls (P < 0.001). A significant correlation was found between macroscopic and MOCART scores (P < 0.001). Comparable mean T2 values were found between adjacent cartilage and repair tissue in the experimental group (P > 0.05). For zonal T2 value evaluation, there were no significant zonal T2 differences for repair tissue in controls (P > 0.05). For the experimental group, zonal T2 variation was found in repair tissue (P < 0.05). MRI, macroscopy and histology showed better repair results and bony incorporation in mosaicplasty with the tissue-engineered cartilage group than those of the single mosaicplasty group. Mosaicplasty with the tissue-engineered cartilage is a promising approach to repair osteochodndral defects. Morphological MRI and T2 mapping provide a non-invasive method for monitoring the maturation and integration of cartilage repair tissue in vivo.

The suppression of hypoxia-inducible factor and vascular endothelial growth factor by siRNA does not affect the radiation sensitivity of multicellular tumor spheroids.

BACKGROUND: The hypoxic microenvironment is closely associated with the radiation resistance of tumor cells. Hypoxia induces several genes such as hypoxia-inducible factor (HIF-1) and vascular endothelial growth factor (VEGF) to promote tumor cell growth and survival. The up-regulated expression levels of HIF-1 and VEGF in tumor cells also correlate with their resistance to radiation, suggesting that these genes are potential therapeutic targets for strategies designed to enhance radiation effects. To further investigate this possibility, we investigated the effects of suppressing these genes upon the radiation sensitivity of cancer cells. We conducted these experiments using multicellular spheroids as a three-dimensional in vitro tumor model and RNA interference as the method of gene suppression. MATERIAL AND METHODS: SQ5 human lung carcinoma cells were treated with HIF-1/VEGF siRNA and/or radiation. Reversed transfection methods were employed for the spheroids. Gene expression was analyzed using quantitative RT-PCR and western blotting. Cell toxicity was qualified by colony formation assay. RESULTS: Compared with monolayer cells, spheroids showed up-regulated expression of HIF-1 and increased radiation resistance. Hypoxic conditions elevated the expression of HIF-1 and VEGF and enhanced the surviving fraction of spheroids after exposure to radiation. However, when the expression of HIF-1 and VEGF was down-regulated by transfection of targeting siRNA, this did not influence the cytotoxic effects of the radiation under either normoxic or hypoxic conditions. CONCLUSIONS: We have established a method to transfect siRNA into spheroid cells. Our current data indicate that the functions of HIF-1 or VEGF are independent of radiation sensitivity in spheroids under either normoxic or hypoxic conditions.