Radiomics analysis for the prediction of locoregional recurrence of locally advanced oropharyngeal cancer and hypopharyngeal cancer.

PURPOSE: By radiomic analysis of the postcontrast CT images, this study aimed to predict locoregional recurrence (LR) of locally advanced oropharyngeal cancer (OPC) and hypopharyngeal cancer (HPC). METHODS: A total of 192 patients with stage III-IV OPC or HPC from two independent cohort were randomly split into a training cohort with 153 cases and a testing cohort with 39 cases. Only primary tumor mass was manually segmented. Radiomic features were extracted using PyRadiomics, and then the support vector machine was used to build the radiomic model with fivefold cross-validation process in the training data set. For each case, a radiomics score was generated to indicate the probability of LR. RESULTS: There were 94 patients with LR assigned in the progression group and 98 patients without LR assigned in the stable group. There was no significant difference of TNM staging, treatment strategies and common risk factors between these two groups. For the training data set, the radiomics model to predict LR showed 83.7% accuracy and 0.832 (95% CI 0.72, 0.87) area under the ROC curve (AUC). For the test data set, the accuracy and AUC slightly declined to 79.5% and 0.770 (95% CI 0.64, 0.80), respectively. The sensitivity/specificity of training and test data set for LR prediction were 77.6%/89.6%, and 66.7%/90.5%, respectively. CONCLUSIONS: The image-based radiomic approach could provide a reliable LR prediction model in locally advanced OPC and HPC. Early identification of those prone to post-treatment recurrence would be helpful for appropriate adjustments to treatment strategies and post-treatment surveillance.

Pretreatment diffusion-weighted imaging for prediction of relapsed and refractory primary central nervous system lymphoma.

Objectives: A subset of primary central nervous system lymphoma (PCNSL) has been shown to undergo an early relapsed/refractory (R/R) period after first-line chemotherapy. This study investigated the pretreatment clinical and MRI features to predict R/R in PCNSL, emphasizing the apparent diffusion coefficient (ADC) values in diffusion-weighted imaging (DWI). Methods: This retrospective study investigated the pretreatment MRI features for predicting R/R in PCNSL. Only patients who had undergone complete preoperative and postoperative MRI follow-up studies were included. From January 2006 to December 2021, 52 patients from two medical institutions with a diagnosis of PCNSL were included (median follow-up time, 26.3 months). Among these, 24 (46.2%) had developed R/R (median time to relapse, 13 months). Cox proportional hazard regression analyses were performed to determine hazard ratios for all parameters. Results: Significant predictors of R/R in PCNSL were female sex, complete response (CR) to first-line chemotherapy, and ADC value/ratio (p < 0.05). Cut-off points of ADC values and ADC ratios for prediction of R/R were 0.68 × 10-3 mm2/s and 0.97, with AUCs of 0.78 and 0.77, respectively (p < 0.05). Multivariate Cox proportional hazards analysis showed that failure of CR to first-line chemotherapy and low ADC values (<0.68 × 10-3 mm2/s) were significant risk factors for R/R, with hazard ratios of 5.22 and 14.45, respectively (p < 0.05). Kaplan-Meier analysis showed that lower ADC values and ratios predicted significantly shorter progression-free survival (p < 0.05). Conclusion: Pretreatment ADC values in DWI offer quantitative valuable information for the treatment planning in PCNSL.

Unnecessary radiation exposure during diagnostic radiography in infants in a neonatal intensive care unit: a retrospective cohort study.

Unnecessary radiation exposure (URE) during radiographic examination is an issue among infants in neonatal intensive care units (NICUs). The causes of URE have not been fully explored. This study investigated the incidence and identified the causes of URE in infants during diagnostic radiography in a NICU. This was a retrospective cohort study. We retrieved and analysed requests and radiographs taken at a tertiary NICU between September and November 2018. URE was defined as the rate of discordance between requests and images taken (DisBRI) and unnecessary radiation exposure in irrelevant regions (UREIR) during radiography. We compared the rates of URE between very low-birth-weight (VLBW, birth weight < 1500 g) infants and non-VLBW infants. A total of 306 radiographs from 88 infants were taken. The means ± standard deviations (SDs) of gestational age and birth weight were 35.7 ± 3.6 weeks and 2471 ± 816 g, respectively. Each infant underwent an average of 3.5 radiographs. The DisBRI rate was 1.3% and was mostly related to poor adherence to requests. The UREIR rates in thoraco-abdominal babygrams were 89.6% for the head, 14.8% for the elbows and 18.4% for the knee and were mainly related to improper positioning of and collimation in infants while performing radiography. The UREIR rates for the head, knee and ankle were higher in VLBW infants than in non-VLBW infants (94.6% vs. 85.6%, 27.0% vs. 11.5% and 5.4% vs. 0.7%, respectively, p < 0.05). CONCLUSIONS: URE during diagnostic radiography is common in sick infants and is mainly related to improper positioning and collimation during examinations. Adherence to protocols when performing radiographic examination or using ultrasonography may be a solution to reduce URE in infants in NICUs. WHAT IS KNOWN: • The risk of unnecessary radiation exposure (URE) during radiography has been a common and important issue in sick infants in neonatal intensive care units (NICUs). • The new point-of-care ultrasound (POCUS) technique decreases the need for chest films and prevents radiation exposure in neonates. WHAT IS NEW: • In the NICU, URE is still a common issue in critically ill infants during radiographic examinations. The causes of URE during diagnostic radiography are mainly due to improper positioning and collimation during examinations. • The incidence of URE in irrelevant regions is higher in very low-birth-weight (VLBW) infants than in non-VLBW infants.

A deep learning-based method for the diagnosis of vertebral fractures on spine MRI: retrospective training and validation of ResNet.

PURPOSE: To improve the performance of less experienced clinicians in the diagnosis of benign and malignant spinal fracture on MRI, we applied the ResNet50 algorithm to develop a decision support system. METHODS: A total of 190 patients, 50 with malignant and 140 with benign fractures, were studied. The visual diagnosis was made by one senior MSK radiologist, one fourth-year resident, and one first-year resident. The MSK radiologist also gave the binary score for 15 qualitative imaging features. Deep learning was implemented using ResNet50, using one abnormal spinal segment selected from each patient as input. The T1W and T2W images of the lesion slice and its two neighboring slices were considered. The diagnostic performance was evaluated using tenfold cross-validation. RESULTS: The overall reading accuracy was 98, 96, and 66% for the senior MSK radiologist, fourth-year resident, and first-year resident, respectively. Of the 15 imaging features, 10 showed a significant difference between benign and malignant groups with p < = 0.001. The accuracy achieved by using the ResNet50 deep learning model for the identified abnormal vertebral segment was 92%. Compared to the first-year resident's reading, the model improved the sensitivity from 78 to 94% (p < 0.001) and the specificity from 61 to 91% (p < 0.001). CONCLUSION: Our deep learning-based model may provide information to assist less experienced clinicians in the diagnosis of spinal fractures on MRI. Other findings away from the vertebral body need to be considered to improve the model, and further investigation is required to generalize our findings to real-world settings.

Clinical application of mask region-based convolutional neural network for the automatic detection and segmentation of abnormal liver density based on hepatocellular carcinoma computed tomography datasets.

The aim of the study was to use a previously proposed mask region-based convolutional neural network (Mask R-CNN) for automatic abnormal liver density detection and segmentation based on hepatocellular carcinoma (HCC) computed tomography (CT) datasets from a radiological perspective. Training and testing datasets were acquired retrospectively from two hospitals of Taiwan. The training dataset contained 10,130 images of liver tumor densities of 11,258 regions of interest (ROIs). The positive testing dataset contained 1,833 images of liver tumor densities with 1,874 ROIs, and negative testing data comprised 20,283 images without abnormal densities in liver parenchyma. The Mask R-CNN was used to generate a medical model, and areas under the curve, true positive rates, false positive rates, and Dice coefficients were evaluated. For abnormal liver CT density detection, in each image, we identified the mean area under the curve, true positive rate, and false positive rate, which were 0.9490, 91.99%, and 13.68%, respectively. For segmentation ability, the highest mean Dice coefficient obtained was 0.8041. This study trained a Mask R-CNN on various HCC images to construct a medical model that serves as an auxiliary tool for alerting radiologists to abnormal CT density in liver scans; this model can simultaneously detect liver lesions and perform automatic instance segmentation.

Imaging biomarkers for evaluating tumor response: RECIST and beyond.

Response Evaluation Criteria in Solid Tumors (RECIST) is the gold standard for assessment of treatment response in solid tumors. Morphologic change of tumor size evaluated by RECIST is often correlated with survival length and has been considered as a surrogate endpoint of therapeutic efficacy. However, the detection of morphologic change alone may not be sufficient for assessing response to new anti-cancer medication in all solid tumors. During the past fifteen years, several molecular-targeted therapies and immunotherapies have emerged in cancer treatment which work by disrupting signaling pathways and inhibited cell growth. Tumor necrosis or lack of tumor progression is associated with a good therapeutic response even in the absence of tumor shrinkage. Therefore, the use of unmodified RECIST criteria to estimate morphological changes of tumor alone may not be sufficient to estimate tumor response for these new anti-cancer drugs. Several studies have reported the low reliability of RECIST in evaluating treatment response in different tumors such as hepatocellular carcinoma, lung cancer, prostate cancer, brain glioma, bone metastasis, and lymphoma. There is an increased need for new medical imaging biomarkers, considering the changes in tumor viability, metabolic activity, and attenuation, which are related to early tumor response. Promising imaging techniques, beyond RECIST, include dynamic contrast-enhanced computed tomography (CT) or magnetic resonance imaging (MRI), diffusion-weight imaging (DWI), magnetic resonance spectroscopy (MRS), and 18 F-fluorodeoxyglucose (FDG) positron emission tomography (PET). This review outlines the current RECIST with their limitations and the new emerging concepts of imaging biomarkers in oncology.

Internal Derangement of the Shoulder Joint in Asymptomatic Professional Baseball Players.

RATIONALE AND OBJECTIVES: To evaluate the influence of throwing activity on shoulder morphology and the difference in shoulder morphology on MRI between asymptomatic professional baseball players and volunteers who play baseball as a recreational activity. MATERIALS AND METHODS: This retrospective case-control study included 68 asymptomatic professional baseball players (32 pitchers, 36 batters) and 30 male volunteers. Morphologic changes in the following shoulder structures were assessed on MRI: rotator cuff, glenoid labrum, humeral head, subacromial-subdeltoid bursa, subcoracoid bursa, long head of the biceps tendon, deltoid muscle, acromion, and clavicle. RESULTS: Partially torn supraspinatus, posterior glenoid or labral lesions, bone marrow edema, intraosseous cysts of the humeral head, and edematous subacromial-subdeltoid bursa were significantly more commonly observed in players (p = 0.01, p < 0.001, p = 0.03, p< 0.001, and p < 0.001). Players with more than 10 years of experience had a significantly higher incidence of patchy intermediate signal abnormality (odds ratio: 3.73, p = 0.03), partial tear in the supraspinatus tendon (odds ratio: 6.20, p = 0.03), and edematous change in the subacromial-subdeltoid bursa (odds ratio: 2.96, p = 0.03). CONCLUSION: The results from our study showed that repetitive throwing activities cause macroscopic structural lesions of the shoulder joints in asymptomatic baseball players. Significance of these lesions is to be determined.

Evaluation of the association between quantitative mammographic density and breast cancer occurred in different quadrants.

BACKGROUND: To investigate the relationship between mammographic density measured in four quadrants of a breast with the location of the occurred cancer. METHODS: One hundred and ten women diagnosed with unilateral breast cancer that could be determined in one specific breast quadrant were retrospectively studied. Women with previous cancer/breast surgery were excluded. The craniocaudal (CC) and mediolateral oblique (MLO) mammography of the contralateral normal breast were used to separate a breast into 4 quadrants: Upper-Outer (UO), Upper-Inner (UI), Lower-Outer (LO), and Lower-Inner (LI). The breast area (BA), dense area (DA), and percent density (PD) in each quadrant were measured by using the fuzzy-C-means segmentation. The BA, DA, and PD were compared between patients who had cancer occurring in different quadrants. RESULTS: The upper-outer quadrant had the highest BA (37 ± 15 cm2) and DA (7.1 ± 2.9 cm2), with PD = 20.0 ± 5.8%. The order of BA and DA in the 4 separated quadrants were: UO > UI > LO > LI, and almost all pair-wise comparisons showed significant differences. For tumor location, 67 women (60.9%) had tumor in UO, 16 (14.5%) in UI, 7 (6.4%) in LO, and 20 (18.2%) in LI quadrant, respectively. The estimated odds and the 95% confidence limits of tumor development in the UO, UI, LO and LI quadrants were 1.56 (1.06, 2.29), 0.17 (0.10, 0.29), 0.07 (0.03, 0.15), and 0.22 (0.14, 0.36), respectively. In these 4 groups of women, the order of quadrant BA and DA were all the same (UO > UI > LO > LI), and there was no significant difference in BA, DA or PD among them (all p > 0.05). CONCLUSIONS: Breast cancer was most likely to occur in the UO quadrant, which was also the quadrant with highest BA and DA; but for women with tumors in other quadrants, the density in that quadrant was not the highest. Therefore, there was no direct association between quadrant density and tumor occurrence.

Differential Effects of Bariatric Surgery Versus Exercise on Excessive Visceral Fat Deposits.

The aim of the present study was to compare differential impacts of bariatric surgery and exercise-induced weight loss on excessive abdominal and cardiac fat deposition.Excessive fat accumulation around the heart may play an important role in the pathogenesis of cardiovascular disease. Recent evidences have suggested that bariatric surgery results in relatively less decrease in epicardial fat compared with abdominal visceral fat and paracardial fat.Sixty-four consecutive overweight or obese subjects were enrolled in the study. Clinical characteristics and metabolic profiles were recorded. The volumes of abdominal visceral adipose tissue (AVAT), abdominal subcutaneous adipose tissue (ASAT), epicardial (EAT), and paracardial adipose tissue (PAT) were measured by computed tomography in the bariatric surgery group (N = 25) and the exercise group (N = 39) at baseline and 3 months after intervention. Subjects in both the surgery and exercise groups showed significant reduction in body mass index (15.97%, 7.47%), AVAT (40.52%, 15.24%), ASAT (31.40, 17.34%), PAT (34.40%, 12.05%), and PAT + EAT (22.31%, 17.72%) (all P < 0.001) after intervention compared with baseline. In both the groups, the decrease in EAT was small compared with the other compartments (P < 0.01 in both groups). Compared with the exercise group, the surgery group had greater loss in abdominal and cardiac visceral adipose tissue (AVAT, ASAT, PAT, EAT+PAT) (P < 0.001), but lesser loss in EAT (P = 0.037).Compared with the exercise group, bariatric surgery results in significantly greater percentage loss of excessive fat deposits except for EAT. EAT, but not PAT, was relatively preserved despite weight reduction in both the groups. The physiological impact of persistent EAT deserves further investigation.

A case-matched study of the differences in bone mineral density 1 year after 3 different bariatric procedures.

BACKGROUND: Studies have reported decreased bone mineral density (BMD) after laparoscopic sleeve gastrectomy (LSG) and laparoscopic Roux-en-Y gastric bypass (LRYGB). Laparoscopic adjustable gastric banded plication (LAGBP) is a novel procedure resulting in a dual restrictive mechanism of weight loss without altering gastrointestinal anatomy. The objectives of this study were to compare the BMD changes at 1 year after LAGBP, LSG, and LRYGB. METHODS: The sample included 120 patients (40 patients [13 men/27 premenopausal women] each in LAGBP, LSG, and LRYGB groups). The mean preoperative age and body mass index were 30.0±6.5 years and 39.5±3.8 kg/m2, respectively. BMD was measured using dual energy X-ray absorptiometry at the lumbar anteroposterior spine and total hip preoperatively and 1 year postoperatively. RESULTS: The mean percentage of excess weight loss was 61.9%±16.8%, 77.1%±12.3%, and 72.7%±17.4% at 1 year after LAGBP, LSG, and LRYGB, respectively. The mean BMD at the lumbar anteroposterior spine remained unchanged in the LSG and LRYGB groups, but significantly increased in the LAGBP group. The mean BMD at the total hip significantly decreased in all groups compared to the preoperative values. However, the mean BMD was significantly higher in the LRYGB than in the LAGBP group. CONCLUSION: Bone loss at the hips was observed in all patients, including those with adequate micronutrient supplementation. LRYGB caused significantly greater bone loss than the other procedures.

Single incision transumbilical laparoscopic Roux-en-Y gastric bypass-our technique.

Laparoscopic Roux-en-Y gastric bypass (LRYGB) is considered the gold standard procedure in bariatric surgery but requires 4-7 ports. We have reported the first single incision transumbilical Roux-en-Y gastric bypass (SITU-RYGB) in 2009 (Huang et al. Obes Surg 19:1711-1715, 2009). Over the years, we have standardized our procedure and this video highlights the same by showing both inside and outside views. This video was shot from outside as well to give better understanding of the procedure. A 4.5-cm incision was made according to the contour of umbilicus and space was created over the sheath to give more range of movement to the instruments. The procedure was carried out using conventional laparoscopic instruments and replicating all the steps of the procedure under adequate visualization. Picture-in-picture effect has been used at important steps. Findings were recorded. The procedure took 96 min without any intraoperative complication. Blood loss was 20 cc. The incision was hardly noticeable at the end of the procedure. We have previously compared our results of SITU-RYGB with that of our multiport RYGB where operative time was longer for SITU-RYGB versus multiport technique (101.1 vs. 81.1 min, P = 0.001) (Huang et al. Surg Obes Relat Dis 8:201-207, 2012). No difference in complications was observed. The SITU-LRYGB patients reported greater satisfaction related to scarring than those who had undergone five-port surgery (P = 0.005). Difference in analgesia requirement was not statistically significant. There was no mortality. Compared with conventional LRYGB, SITU-RYGB resulted in acceptable complications, the same recovery, comparative weight loss, and better patient satisfaction related to scarring.

Renal angiomyolipoma with coexistent hemorrhagic aneurysm formation and fatty thrombus in inferior vena cava: a rare presentation.

Angiomyolipoma (AML) is known as the most common benign mesenchymal tumor of kidney. Usually AMLs present as benign lesions without local invasion or complication. However, few cases of renal AML have been reported with complications such as tumor thrombus extension into inferior vena cava (IVC) or hemorrhagic aneurysm formation. We report a complicated case of renal AML with CT and angiography evidence of hemorrhagic aneurysm formation and IVC thrombus, treated by a combination of selective arterial embolization, radical nephrectomy and thrombectomy. Radiologists and clinicians should be aware that AMLs could have such aggressive behaviors.

Imaging features of posterior limbus vertebrae.

Posterior limbus vertebra (PLV) is the retropulsion of the vertebral ring apophysis resulting from disc herniation through posterior ring physis. Large PLV can cause spinal stenosis, and small PLV can be mistaken as intraspinal disc herniation. Although the clinical presentations were similar, the surgery was quite different. We had experienced preoperative misdiagnosed cases and the surgery could not be finished. Therefore we analyzed the imaging features of PLV in 34 patients in order to prompt appropriate preoperative diagnosis and surgical planning.

Analyzing coronary artery disease in patients with low CAC scores by 64-slice MDCT.

PURPOSE: Coronary artery calcification (CAC) scores are widely used to determine risk for Coronary Artery Disease (CAD). A CAC score does not have the diagnostic accuracy needed for CAD. This work uses a novel efficient approach to predict CAD in patients with low CAC scores. MATERIALS AND METHODS: The study group comprised 86 subjects who underwent a screening health examination, including laboratory testing, CAC scanning, and cardiac angiography by 64-slice multidetector computed tomographic angiography. Eleven physiological variables and three personal parameters were investigated in proposed model. Logistic regression was applied to assess the sensitivity, specificity, and accuracy of when using individual variables and CAC score. Meta-analysis combined physiological and personal parameters by logistic regression. RESULTS: The diagnostic sensitivity of the CAC score was 14.3% when the CAC score was ≤30. Sensitivity increased to 57.13% using the proposed model. The statistically significant variables, based on beta values and P values, were family history, LDL-c, blood pressure, HDL-c, age, triglyceride, and cholesterol. CONCLUSIONS: The CAC score has low negative predictive value for CAD. This work applied a novel prediction method that uses patient information, including physiological and society parameters. The proposed method increases the accuracy of CAC score for predicting CAD.

Focal bone abnormality as a complication of ultrasound diathermy: a report of eight cases.

PURPOSE: To review the magnetic resonance (MR) imaging findings in eight patients who developed marrow lesions after undergoing physiotherapy with use of ultrasound diathermy. MATERIALS AND METHODS: The authors retrospectively reviewed the medical charts and MR images of eight patients (six women and two men aged 22-69 years) who received ultrasound diathermy treatment for a variety of soft tissue injuries involving primarily the knee, shoulder, and wrist. All patients underwent MR imaging without the use of intravenous gadolinium-based contrast material. The institutional review board approved the study, and the requirement to obtain informed consent was waived. RESULTS: MR imaging of all patients revealed subcortical rim or arc lesions with low signal intensity on T1-weighted images and high signal intensity on T2-weighted images, without involvement of the deeper aspect of the bone marrow. The imaging features of the lesions were similar to those of focal osteonecrosis. Follow-up MR imaging performed in three patients approximately 2-3 months after cessation of ultrasound therapy revealed resolution of the bone lesions. Symptoms resolved in all patients. CONCLUSION: This study demonstrated that ultrasound diathermy may produce an osseous injury. The abnormality itself was usually mild and transient, with apparent full recovery after termination of therapy.

Preoperative embolization of carotid body tumor by direct percutaneous intratumoral injection of N-butyl cyanoacrylate glue assisted with balloon protection technique.

Substantial intraoperative bleeding during surgical removal of carotid body tumor may be a major problem in the management of these highly vascularized tumors. Traditional preoperative embolization via a transarterial access has proved effective but is often limited by complex vascular anatomy and small feeding vessels that is difficult to catheterize. We report two cases of carotid body tumor treated with direct puncture and intratumoral injection of N-butyl cyanoacrylate glue (NBCA) assisted with balloon protection technique for preoperative devascularization. The result was impressive and minimal bleeding loss during surgery was observed.

Postoperative lumbar spine: modified radiographic projections for detection of bone defects in cadavers.

PURPOSE: Special radiographic projections were evaluated in two cadaveric specimens for depicting postoperative changes after five different lower lumbar surgical procedures. Available literature concerning special radiographic projections of the lumbar spine is limited. The objective of this study was to establish a special radiographic projection that is useful for depicting postoperative changes after lumbar surgical procedures. MATERIALS AND METHODS: Five different procedures were performed on two cadaveric lumbar spines: laminotomy, total laminectomy, foraminotomy, surgical creation of pars interarticularis defect, and partial facetectomy. A series of radiographs, including routine views and combinations of various obliquity and cephalad angulation, were obtained preoperatively and after each operation. Film analysis was done using a four-point rating system to document the degree of visualization of the postsurgical bone defect at each stage of surgery at each lumbar segment. The best projections were determined by summation of the rating scores of the three lumbar segments. The scores of each projection in different procedures were also summed to determine the best view for clinical use. RESULTS: The laminotomy defects were more obvious on the shallow-obliquity and low-angulation radiographs. The postoperative changes of total laminectomy were almost equally identified on the AP and lateral views and most of the compound views. The bone changes of foraminotomy were best identified on the 45 degrees routine view. The 30 degrees-15 degrees and 45 degrees-15 degrees compound views were best for depicting a postoperative pars defect. None of the projections delineated the bone changes of partial facetectomy. The 30 degrees-15 degrees compound view had the highest summation of rating scores of the five surgical procedures. CONCLUSION: The results of this study suggest that the 30 degrees-15 degrees compound view could be useful for the assessment of the postoperative lumbar spine. Further verification of its value requires a large clinical study.

Optimizing scanning phases in detecting small (<2 cm) hepatocellular carcinoma: whole-liver dynamic study with multidetector row CT.

OBJECTIVE: To define the optimal scanning phases for detecting small hepatocellular carcinomas (HCCs) with whole-liver dynamic helical computed tomography. METHODS: Sixty-one patients with 112 hypervascular HCCs smaller than 2 cm underwent 7-phase dynamic study from the early arterial to the late equilibrium phases of the entire liver. Proof of neoplasms was based on biopsy results and computed tomography with iodized oil. Time-density curves of the individual tumor and the liver were compared. RESULTS: Of 112 hypervascular nodules, the late arterial phase had the best liver-tumor conspicuity (P < 0.001). Ninety-one nodules (81%) had peak liver-tumor contrast in late arterial phase, and only 21 (19%) in the early arterial phase. All the hypervascular HCCs became isoattenuating to the regional parenchyma before the late portal venous phase (120th second). CONCLUSION: The late arterial and late portal venous phases are recommended for detecting small HCC smaller than 2 cm.

Proton magnetic resonance spectroscopy and diffusion-weighted imaging in intracranial cystic mass lesions.

BACKGROUND: The differential diagnosis of various intracranial cystic lesions is sometimes difficult on the basis of CT or MRI findings. Our objective was to evaluate (1)H MRS and DWI in the differential diagnosis of these lesions and in comparison with conventional MRI. METHODS: Fifty patients with intracranial cystic lesions (21 pyogenic abscesses, 23 tumor cysts, 3 epidermoid cysts, and 3 arachnoid cysts) were evaluated with conventional MRI, DWI, and in vivo (1)H MRS. Preoperative diagnosis of the lesions was based on the results of DWI and in vivo MRS. All DWI and (1)H MRS studies were performed with a clinical 1.5-T system. The DWI was performed using single-shot spin-echo echo-planar pulse sequence with b = 1000 s/mm(2). The ADC value was measured. Diagnostic accuracy of conventional MRI, DWI, and in vivo (1)H MRS was calculated with respect to a final diagnosis of brain abscess vs nonabscess cystic tumor. RESULTS: Lactate and cytosolic amino acids with/without succinate, acetate, and alanine were observed in 18 of 21 cases of abscesses on MRS. In 3 cases of epidermoid cysts, lactate was observed and could be differentiated from 3 cases of arachnoid cysts, which showed only minimal lactate. Only lactate was seen in 14 of 23 patients with tumor cysts, whereas both lipid/lactate and choline were visible in 9 patients with tumor cysts. Increased signal was seen in 20 of 21 patients with abscesses and 3 patients with epidermoid cysts on DWI. Decreased signal was observed in 22 of 23 patients with tumor cysts and 3 patients with arachnoid cyst on DWI. Diagnostic accuracy, sensitivity, specificity, positive predictive value, and negative predictive value of conventional MRI for the differentiation of brain abscess from nonabscess cystic tumor were 61.4%, 61.9%, 60.9%, 59.1%, and 63.6%, respectively, whereas they were 93.2%, 85.7%, 100%, 100%, and 88.5% with MRS; 95.5%, 95.2%, 95.7%, 95.2%, and 95.7% with DWI; and 97.7%, 95.2%, 100%, 100%, and 95.8% with MRS and DWI. Magnetic resonance imaging, when combined with in vivo MRS and DWI, accurately predicted the diagnosis in 47 (94%) of 50 and 48 (96%) of 50 of the cases, respectively. CONCLUSIONS: Proton MRS and DWI are useful as additional diagnostic modalities in differentiating intracranial cystic lesions. Combination of DWI with calculated ADC values and metabolite spectrum acquired by MRS add more information to MRI in the differentiation of intracranial cystic mass lesions.