Assessing the use of digital radiography and a real-time interactive pulmonary nodule analysis system for large population lung cancer screening

Rationale and objectives

To assess the use of chest digital radiograph (DR) assisted with a real-time interactive pulmonary nodule analysis system in large population lung cancer screening.

Materials and methods

346 DR/CR patient studies with corresponding CT images were selected from 12,500 patients screened for lung cancer from year 2007 to 2009. Two expert chest radiologists established CT-confirmed Gold Standard of nodules on DR/CR images with consensus. These cases were read by eight other chest radiologists (participating radiologists) first without using a real-time interactive pulmonary nodule analysis system and then re-read using the system. Performances of participating radiologists and the computer system were analyzed.

Results

The computer system achieved similar performance on DR and CR images, with a detection rate of 76% and an average FPs of 2.0 per image. Before and after using the computer-aided detection system, the nodule detection sensitivities of the participating radiologists were 62.3% and 77.3% respectively, and the A_z values increased from 0.794 to 0.831. Statistical analysis demonstrated statically significant improvement for the participating radiologists after using the computer analysis system with a P-value 0.05.

Conclusion

The computer system could help radiologists identify more lesions, especially small ones that are more likely to be overlooked on chest DR/CR images, and could help reduce inter-observer diagnostic variations, while its FPs were easy to recognize and dismiss. It is suggested that DR/CR assisted by the real-time interactive pulmonary nodule analysis system may be an effective means to screen large populations for lung cancer.     

Object position and image magnification in dental panoramic radiography: a theoretical analysis

Objectives

The purpose of our study was to investigate how image magnification and distortion in dental panoramic radiography are influenced by object size and position for a small round object such as a ball bearing used for calibration.

Methods

Two ball bearings (2.5 mm and 6 mm in diameter) were placed at approximately the same position between the teeth of a plastic skull and radiographed 21 times. The skull was replaced each time. Their images were measured by software using edge detection and ellipse-fitting algorithms. Using a standard definition of magnification, equations were derived to enable an object''s magnification to be determined from its position and vice versa knowing the diameter and machine parameters.

Results

The average magnification of the 2.5 mm ball bearing was 1.292 (0.0445) horizontally and 1.257 (0.0067) vertically with a mean ratio of 1.028 (0.0322); standard deviations are in parentheses. The figures for the 6 mm ball bearing were 1.286 (0.0068), 1.255 (0.0018) and 1.025 (0.0061), respectively. Derived positions of each ball bearing from magnification were more consistent horizontally than vertically. There was less variation in either direction for the 6 mm ball bearing than the 2.5 mm one.

Conclusions

Automatic measurement of image size resulted in less variation in vertical magnification values than horizontal. There are only certain positions in the focal trough that achieve zero distortion. Object location can be determined from its diameter, measured magnification and machine parameters. The 6 mm diameter ball bearing is preferable to the 2.5 mm one for more reliable magnification measurement and position determination.     

The value of virtual touch tissue image (VTI) and virtual touch tissue quantification (VTQ) in the differential diagnosis of thyroid nodules

Objectives

To explore the value of virtual touch tissue image (VTI) and virtual touch tissue quantification (VTQ) in the differential diagnosis of thyroid nodules.

Methods

One-hundred and seven patients with 113 thyroid nodules were performed conventional ultrasound and acoustic radiation force impulse (ARFI) elastography. The stiffness of the nodules on virtual touch tissue image (VTI) was graded, and the area ratios (AR) of nodules on VTI images versus on B-mode images were calculated. Shear wave velocity (SWV) within the thyroid nodules were measured using virtual touch tissue quantification (VTQ) technique. The pathological diagnosis as the gold standard draws the receiver-operating characteristic curve (ROC) to find the cut-off point of VTI grades, AR and SWV to predict thyroid cancer.

Results

The difference in VTI grades of malignant and benign nodules was statistically significant (P < 0.05), as well as in AR and SWV. There was no significant difference in the AR of nodules or the SWV of nodules in benign group or in malignant group. The sensitivity, specificity, accuracy, positive predictive value (PPV), and negative predictive value (NPV) of VTI grades, AR, and SWV in the differential diagnosis of thyroid nodules were calculated. There was no significant difference in diagnostic accuracy among the three methods.

Conclusion

VTI grades, AR of nodules on VTI images versus on B-mode images and SWV within the nodules can help the differential diagnosis of thyroid nodules.     

Low energy mammogram obtained in contrast-enhanced digital mammography (CEDM) is comparable to routine full-field digital mammography (FFDM)

Purpose

Contrast enhanced digital mammography (CEDM) uses low energy and high energy exposures to produce a subtracted contrast image. It is currently performed with a standard full-field digital mammogram (FFDM). The purpose is to determine if the low energy image performed after intravenous iodine injection can replace the standard FFDM.

Methods

And Materials: In an IRB approved HIPAA compatible study, low-energy CEDM images of 170 breasts in 88 women (ages 26–75; mean 50.3) undergoing evaluation for elevated risk or newly diagnosed breast cancer were compared to standard digital mammograms performed within 6 months. Technical parameters including posterior nipple line (PNL) distance, compression thickness, and compression force on the MLO projection were compared. Mammographic findings were compared qualitatively and quantitatively. Mixed linear regression using generalized estimating equation (GEE) method was performed. Intraclass correlation coefficients (ICC) with 95% confidence interval (95%CI) were estimated to assess agreement.

Results

No statistical difference was found in the technical parameters compression thickness, PNL distance, compression force (p-values: 0.767, 0.947, 0.089). No difference was found in the measured size of mammographic findings (p-values 0.982–0.988). Grouped calcifications had a mean size/extent of 2.1 cm (SD 0.6) in the low-energy contrast images, and a mean size/extent of 2.2 cm (SD 0.6) in the standard digital mammogram images. Masses had a mean size of 1.8 cm (SD 0.2) in both groups. Calcifications were equally visible on both CEDM and FFDM.

Conclusion

Low energy CEDM images are equivalent to standard FFDM despite the presence of intravenous iodinated contrast. Low energy CEDM images may be used for interpretation in place of the FFDM, thereby reducing patient dose.     

Contribution of thin slice (1 mm) oblique coronal proton density-weighted MR images for assessment of anteromedial and posterolateral bundle damage in anterior cruciate ligament injuries

Purpose

To evaluate the diagnostic efficacy of using additional oblique coronal 1 mm proton density-weighted (PDW) MR imaging of the knee for detection and grading anterior cruciate ligament (ACL), anteromedial bundle (AMB) and posterolateral bundle (PLB) injuries.

Materials and methods

We prospectively assessed preoperative MR images of 50 patients (36 men, 14 women; age range, 18–62 years). First, we compared the diagnostic performance of routine sagittal (3 mm) and additional oblique coronal images (1 mm) for ACL tears. Then, we compared the tear types (AMB or PLB) and grade presumed from oblique coronal MR imaging with arthroscopy.

Results

Arthroscopy revealed ACL tear in 24 (48%) patients. There was significant difference between sagittal images and arthroscopy results for ACL tear recognition (p < 0.001). No significant difference was detected for oblique coronal images when compared with arthroscopy results (p = 0.180). Sensitivity and specificity values for ACL tear diagnosis were 37.04% and 95.65% for sagittal images; 74.07% and 91.30% for oblique coronal images. There was no significant difference between arthroscopy and oblique coronal MR images in grading AMB and PLB injuries (p > 0.05).

Conclusion

Addition of thin slice oblique coronal images to conventional sequences could better contribute to better verifying the presence of ACL tear and in determining its grade.     

The run-off resistance (ROR) assessed on MR angiograms may serve as a valid scoring system in patients with symptomatic peripheral arterial disease (PAD) and correlates with the ankle-brachial pressure index (ABI)

Objective

To investigate the correlation between the hemodynamic parameter ankle-brachial pressure index (ABI) and the run-off resistance (ROR) assessed on MR angiograms (MRA) in patients with peripheral arterial disease (PAD) Fontaine Stage I and II and its potential as reliable reporting system in clinical routine.

Methods

Contrast-enhanced MRA was performed in 321 PAD patients using a 1.5 T MR scanner with moving bed technique. The ROR and resting ABI were determined in each patient's leg and correlation analysis was performed using the Pearson test.

Results

A significant negative correlation (r = −.513; p < .001) between ROR (mean 11.03 ± 5.42) and resting ABI (mean .81 ± .26) was identified. An even more pronounced correlation was found in patients younger than median age who had higher ABI values (r = −.608; p < .001).

Conclusion

The ROR scoring system evaluated in this series correlates better with the ABI than previously published scoring systems and could be suggested as reporting system for routine MRA evaluation.     

Paradoxical signal pattern of mediastinal cysts on T2-weighted MR imaging: phantom and clinical study

Purpose

To evaluate the intracystic MRI (magnetic resonance imaging) signal intensity of mediastinal cystic masses on T2-weighted images.

Materials and methods

A phantom study was performed to evaluate the signal intensity of a mediastinal cystic mass phantom (rubber balloon containing water) adjacent to a cardiac phantom pulsing at the rate of 60/min. T2-weighted images (sequence, fast spin echo [FSE] and single shot fast spin echo [SSFSE]) were acquired for the mediastinal cystic mass phantom. Further, a clinical study was performed in 33 patients (16 men, 17 women; age range, 19-85 years; mean, 65years) with thymic cysts or pericardial cysts. In all patients, T2-weighted images (FSE and SSFSE) were acquired. The signal intensity of cystic lesion was evaluated and was compared with that of muscle. A region of interest (ROI) was positioned on the standard MR console, and signal intensity of the cystic mass (cSI), that of the muscle (mSI), and the rate of absolute value of cSI–mSI to standard deviation (SD) of background noise (|cSI–mSI|/SD = CNR [contrast-to-noise ratio]) were measured.

Results

The phantom study demonstrated that the rate phantom-ROI/saline-ROI was higher in SSFSE (0.36) than in FSE (0.19). In clinical cases, the degree of the signal intensity was higher in SSFSE than in FSE. The CNR was significantly higher in SSFSE (mean ± standard deviation, 111.0 ± 47.6) than in FSE (72.8 ± 36.6) (p < 0.001, Wilcoxon signed-rank test).

Conclusions

Anterior mediastinal cysts often show lower signal intensity than the original signal intensity of water on T2-weighted images. SSFSE sequence reduces this paradoxical signal pattern on T2-weighted images, which may otherwise cause misinterpretation when assessing cystic lesions.     

Detection of hypoxic-ischemic brain injury with 3D-enhanced T2* weighted angiography (ESWAN) imaging

Objective

To demonstrate the use of 3D-enhanced T2* weighted angiography (ESWAN) imaging for the observation and quantification of the evolution of brain injury induced by a recently developed model of hypoxic-ischemic brain injury (HI/R) in neonatal piglets.

Methods

For these experiments, newborn piglets were subjected to HI/R injury, during which ESWAN scanning was performed, followed by H&E staining and immunohistochemistry of AQP-4 expression.

Results

In the striatum, values from T2* weighted magnetic resonance imaging (MRI) increased and reached their highest level at 3 days post injury, whereas T2* values increased and peaked at 24 h in the subcortical region. The change in T2* values was concordant with brain edema. Phase values in the subcortical border region were not dependent on time post-injury. Magnitude values were significantly different from the control group, and increased gradually over time in the subcortical border region. Susceptibility-weighted images (SWI) indicated small petechial hemorrhages in the striatum and thalamus, as well as dilated intramedullary veins.

Conclusion

SWI images can be used to detect white and gray matter microhemorrhages and dilated intramedullary veins. The T2*, phase, and magnitude map can also reflect the development of brain injury. Our data illustrate that ESWAN imaging can increase the diagnostic sensitivity and specificity of MRI in neonatal hypoxic-ischemic encephalopathy.     

Multidetector computed tomography (MDCT) manifestations of the normal duodenal papilla

Objective

This study aimed to investigate Multidetector Computed Tomography (MDCT) manifestations of the normal duodenal papilla, thereby improving the knowledge on the CT manifestations of the normal anatomy of the duodenal papilla.

Methods

A retrospective study was conducted by reviewing the CT results of 70 normal duodenal papilla cases examined by 64-MDCT. The analysis particularly focused on the position, size, morphology, and enhancement pattern of the duodenal papilla, as well as the ampulla of Vater.

Results

In axial images, the average base diameter of the duodenal papilla was (7.3 ± 1.4) mm, whereas the average height was (6.5 ± 1.8) mm. Majority of the duodenal papilla (52.9%, 37/70) showed a round shape. In most cases (97.1%, 68/70), the duodenal papilla were located at the middle and lower third of the descending duodenum. In 84.3% of the cases (59/70), the arterial phase enhanced CT scan images were optimal for the visualization of the papilla. The “target sign” could be clearly identified from arterial phase images in 71.4% (50/70) of the cases. In 72.9% (51/70) of the cases, the ampulla of Vater had a common channel (Y type).

Conclusion

64-MDCT can clearly visualize the normal anatomy of the duodenal papilla and surrounding structures, thereby providing valuable information for the diagnosis and treatment of diseases in this region.     

Influence of radiation dose and iterative reconstruction algorithms for measurement accuracy and reproducibility of pulmonary nodule volumetry: A phantom study

Purpose

To evaluate the influence of radiation dose settings and reconstruction algorithms on the measurement accuracy and reproducibility of semi-automated pulmonary nodule volumetry.

Materials and methods

CT scans were performed on a chest phantom containing various nodules (10 and 12 mm; +100, −630 and −800 HU) at 120 kVp with tube current–time settings of 10, 20, 50, and 100 mAs. Each CT was reconstructed using filtered back projection (FBP), iDose⁴ and iterative model reconstruction (IMR). Semi-automated volumetry was performed by two radiologists using commercial volumetry software for nodules at each CT dataset. Noise, contrast-to-noise ratio and signal-to-noise ratio of CT images were also obtained. The absolute percentage measurement errors and differences were then calculated for volume and mass. The influence of radiation dose and reconstruction algorithm on measurement accuracy, reproducibility and objective image quality metrics was analyzed using generalized estimating equations.

Results

Measurement accuracy and reproducibility of nodule volume and mass were not significantly associated with CT radiation dose settings or reconstruction algorithms (p > 0.05). Objective image quality metrics of CT images were superior in IMR than in FBP or iDose⁴ at all radiation dose settings (p < 0.05).

Conclusion

Semi-automated nodule volumetry can be applied to low- or ultralow-dose chest CT with usage of a novel iterative reconstruction algorithm without losing measurement accuracy and reproducibility.     

Gastrointestinal stromal tumors (GISTs): Diagnostic value of multi-detector computed tomography

Background

GISTs are considered the commonest mesenchymal neoplasms of the GIT originating from the gastrointestinal tract, mesentery, omentum, or retroperitoneum. They arise within the gut musculosa having exophytic growth pattern. They characteristically have hemorrhage, necrosis, or cyst formation that appears as focal areas of low attenuation on computed tomographic images.With multidetector CT (MDCT) capabilities, the exact origin of the GIST can be easily confirmed to differentiate it from other mesenchymal origin tumors.

Materials and methods

Retrospective search for GIST cases in the digital archives of our institute, during a 15 months duration (April 2010 to July 2011). Workstation reviewing of their imaging features.

Results

This study included 24 pathologically proved GISTs (12 gastric, 8 small intestinal, two colonic, one mesenteric and one anorectal) demonstrating the radiologic features of GISTs depending on tumor size and organ of origin.

Conclusion

MDCT with its multiplanar capabilities and isotropic z-axis resolution allows the radiologist to examine the detailed relation of the mass to the surrounding bowel wall, vessels and other structures. It also helps to map the vascular pedicle in cases of hypervascular GIST’s, which may be crucial for trans-catheter embolization in cases presenting with acute gastrointestinal bleeding.     

Comparison of axial, coronal, and primary 3D review in MDCT colonography for the detection of small polyps: a phantom study

Purpose

The purpose of this phantom study is to compare the influence of the reading technique (axial images alone in comparison to 3D endoluminal, coronal, and combined 2D/3D review methods) on the sensitivity and inter-reader variability with MDCT colonography for the detection of small colonic polyps.

Methods

An anthropomorphic pig colon phantom with 75 randomly distributed simulated small polyps of 2–8 mm size, was distended with air and scanned in a water phantom using multidetector-row CT with 4 mm × 1 mm collimation. Three radiologists rated the presence of polyps on a five-point scale. Performance with axial sections alone was compared to the performance with coronal sections, virtual endoscopy (VE), and a combined 2D/3D approach. We calculated sensitivities for polyp detection and used ROC analysis for data evaluation.

Results

There was no significant difference between the mean area under the curve (A_z) for axial images and VE (A_z = 0.934 versus 0.932), whereas coronal images were significantly inferior (A_z = 0.876) to both. The combined 2D/3D approach yielded the best results, with an A_z of 0.99. Differences in sensitivity between individual readers were significant in axial images (sensitivity, 75–93%, p = 0.001) and coronal images (sensitivity, 69–80%, p = 0.028), but became non-significant with VE (83–88%, p = 0.144) and the combined 2D/3D approach (95–97%, p = 0.288).

Conclusion

Evaluation of axial sections alone leads to significant differences in detection rates between individual observers. A combined 2D/3D evaluation improves sensitivities for polyp detection and reduces inter-individual differences to an insignificant level.     

Role of multidetector CT (MDCT) in differentiation between adenomyomatois and gall bladder cancer

Introduction

Adenomyomatosis, or diverticular disease of the gallbladder, is an acquired hyperplastic lesion characterized by excessive proliferation of the surface epithelium with deepened invaginations extending into the thickened muscular layer of the gallbladder wall. The radiologic evidence of both adenomyomatosis and gallbladder cancer is focal or diffuse thickening of the gallbladder wall (1).Focal or diffuse gallbladder wall thickening is a relatively frequent observation on CT and is often incidental. It can be a dilemma for interpreting radiologists (2).

Aim of the work

The purpose of this study is to determine the role of MDCT in differentiating adenomyomatosis from gallbladder cancer.

Patients

The study included 20 patients already pathologically diagnosed as adenomyomatosis or gall bladder cancer, and who had undergone pre-operative CT.

Methods

Preoperative CT is reviewed for the presence and nature of morphologic gallbladder abnormalities, including the presence of intramural diverticula (Pearl necklace sign) and the presence of a non-interrupted mucosal enhancement line.

Results

Pearl necklace sign was 80% accurate for the diagnosis of adenomyomatosis. Mucosal enhancement line was 100% accurate for the same diagnosis.

Conclusion

MDCT is an accurate technique for differentiating between gall bladder adenomayomatosis and cancer.     

Diffusion-weighted MRI of the prostate at 3.0 T: Comparison of endorectal coil (ERC) MRI and phased-array coil (PAC) MRI—The impact of SNR on ADC measurement

Purpose

To compare ADC values measured from diffusion-weighted MR (DW-MR) images of the prostate obtained with both endorectal and phased-array coils (ERC + PAC) to those from DW-MRI images obtained with an eight-channel torso phased-array coil (PAC) at 3.0 T.

Methods

The institutional review board issued a waiver of informed consent for this HIPAA-compliant study. Twenty-five patients with biopsy-proven prostate cancer underwent standard 3-T MRI using 2 different coil arrangements (ERC + PAC and PAC only) in the same session. DW-MRI at five b-values (0, 600, 1000, 1200, and 1500 s/mm²) were acquired using both coil arrangements. On b = 0 images, signal-to-noise ratios (SNRs) were measured as the ratio of the mean signal from PZ and TZ ROIs to the standard deviation from the mean signal in an artifact-free ROI in the rectum. Matching regions-of-interest (ROIs) were identified in the peripheral zone and transition zone on ERC-MRI and PAC-MRI. For each ROI, mean ADC values for all zero and non-zero b-value combinations were computed.

Results

Mean SNR with ERC-MRI at PZ (66.33 ± 27.07) and TZ (32.69 ± 12.52) was 9.27 and 5.52 times higher than with PAC-MRI ((7.32 ± 2.30) and (6.13 ± 1.56), respectively) (P < 0.0001 for both). ADCs from DW-MR images obtained with all b-values in the PZ and TZ were significantly lower with PAC-MRI than with ERC-MRI (P < 0.001 for all).

Conclusion

Lower SNR of DW-MR images of the prostate obtained with a PAC can significantly decrease ADC values at higher b-values compared to similar measurements obtained using the ERC. To address these requirements, clinical MR systems should have image processing capabilities which incorporate the noise distribution.     

Ultrasound and computed tomography features of primary acinic cell carcinoma in the parotid gland: A retrospective study

Objective

The aim of this study was to characterize the ultrasound (US) and computed tomography (CT) findings of primary acinic cell carcinoma (AciCC) of the parotid gland.

Subjects and methods

Seventy patients (70 lesions) with histopathologically proven AciCC underwent US or CT examination. The following characteristics were assessed on US images: size, shape, border, echogenicity, echotexture, internal structure, distal acoustic enhancement, and vascularity. The following characteristics were evaluated on CT images: size, shape, border, density, CT values on plain and contrast-enhanced scans, enhancement pattern, enhancement degree, and surrounding bone destruction.

Results

On US images, lesions were irregular, well-defined, hypoechoic, heterogeneous, and poorly vascularized. On CT images, lesions were regular and well-defined, and showed slight heterogeneous enhancement.

Conclusion

These findings suggest that most primary AciCCs show benign features on US and CT.     

4D phase contrast flow imaging for in-stent flow visualization and assessment of stent patency in peripheral vascular stents - A phantom study

Purpose

4D phase contrast flow imaging is increasingly used to study the hemodynamics in various vascular territories and pathologies. The aim of this study was to assess the feasibility and validity of MRI based 4D phase contrast flow imaging for the evaluation of in-stent blood flow in 17 commonly used peripheral stents.

Materials and methods

17 different peripheral stents were implanted into a MR compatible flow phantom. In-stent visibility, maximal velocity and flow visualization were assessed and estimates of in-stent patency obtained from 4D phase contrast flow data sets were compared to a conventional 3D contrast-enhanced magnetic resonance angiography (CE-MRA) as well as 2D PC flow measurements.

Results

In all but 3 of the tested stents time-resolved 3D particle traces could be visualized inside the stent lumen. Quality of 4D flow visualization and CE-MRA images depended on stent type and stent orientation relative to the magnetic field. Compared to the visible lumen area determined by 3D CE-MRA, estimates of lumen patency derived from 4D flow measurements were significantly higher and less dependent on stent type. A higher number of stents could be assessed for in-stent patency by 4D phase contrast flow imaging (n = 14) than by 2D phase contrast flow imaging (n = 10).

Conclusions

4D phase contrast flow imaging in peripheral vascular stents is feasible and appears advantageous over conventional 3D contrast-enhanced MR angiography and 2D phase contrast flow imaging. It allows for in-stent flow visualization and flow quantification with varying quality depending on stent type.     

Lingering fat signals with CHESS in simultaneous imaging of both hands can be improved with rice pads in both 1.5 T and 3.0 T

Objectives

To investigate whether rice pads can eliminate lingering fat signals of the complex surface shape of both hands that occur with chemical shift selective (CHESS) at 1.5 T and 3.0 T.

Materials and methods

T1-weighted images were obtained with CHESS using 1.5 T and 3.0 T systems. The same imaging parameters were used with and without rice pads on the coronal plane of both hands in 10 healthy volunteers. The fat-suppression effects were classified into four categories and scored for images, and visual evaluations were performed by one radiologist and one radiologic technologist.

Results

At 1.5 T, the mean evaluation score was 1.55 for images obtained without rice pads and 3.50 for images obtained with rice pads. At 3.0 T, the mean evaluation score was 1.10 for images obtained without rice pads and 3.20 for images obtained with rice pads. With both systems, images obtained with the rice pads showed significantly better fat suppression effects than images obtained without rice pads (P < 0.0001, P < 0.0001).

Conclusions

It was confirmed that lingering fat signals are eliminated and good fat-suppressed images are obtained with the use of rice pads at 1.5 T and 3.0 T. Rice pads are therefore useful with at 1.5 T and 3.0 T, which are currently becoming more widely used.     

Potential contribution of multiplanar reconstruction (MPR) to computer-aided detection of lung nodules on MDCT

Purpose

To evaluate potential benefits of using multiplanar reconstruction (MPR) in computer-aided detection (CAD) of lung nodules on multidetector computed tomography (MDCT).

Materials and methods

MDCT datasets of 60 patients with suspected lung nodules were retrospectively collected. Using “second-read” CAD, two radiologists (Readers 1 and 2) independently interpreted these datasets for the detection of non-calcified nodules (≥4 mm) with concomitant confidence rating. They did this task twice, first without MPR (using only axial images), and then 4 weeks later with MPR (using also coronal and sagittal MPR images), where the total reading time per dataset, including the time taken to assess the detection results of CAD software (CAD assessment time), was recorded. The total reading time and CAD assessment time without MPR and those with MPR were statistically compared for each reader. The radiologists’ performance for detecting nodules without MPR and the performance with MPR were compared using jackknife free-response receiver operating characteristic (JAFROC) analysis.

Results

Compared to the CAD assessment time without MPR (mean, 69 s and 57 s for Readers 1 and 2), the CAD assessment time with MPR (mean, 46 s and 45 s for Readers 1 and 2) was significantly reduced (P < 0.001). For Reader 1, the total reading time was also significantly shorter in the case with MPR. There was no significant difference between the detection performances without MPR and with MPR.

Conclusion

The use of MPR has the potential to improve the workflow in CAD of lung nodules on MDCT.     

Value of contrast enhanced spoiled gradient (SPGR) MR and MIP MR imaging in diagnosis of peri-anal fistula

Purpose

To assess the value of the combination of contrast enhanced T1 spoiled gradient (SPGR) MR and maximum intensity projection (MIP) MR imaging in the complete pre-operative evaluation of peri-anal fistula.

Patients and methods

This prospective study contained 28 patients with clinical diagnosis of peri-anal fistula, they were performed MRI using the following sequences in both axial and coronal planes: Pre contrast T2FSE, T1FSE and Post contrast SPGR. MIP reformated images were done using the SPGR sequence. Fistulas were classified according to Parks (6) classification, they were evaluated regarding site, type, extensions, complications and diagnostic accuracy of each sequence. Our findings were correlated with operative findings.

Results

Fourteen patients had inter-sphincteric fistulas (50%), 8 patients had trans-sphincteric fistulas (28.6%) and 6 patients had supra-sphincteric fistulas (21.4%). Simple non branching tracts were found in 22 patients, branching tracts in 6 patients, abscess cavity in 5 patients, horseshoe extension in 4 patients. Overall diagnostic accuracy of post contrast T1 SPGR was 97.3% and MIP MR imaging was 100%. Post contrast T1 SPGR accurately evaluated all patients but missed one faint horseshoe extension and other fine para anal branches. MIP imaging accurately evaluated all the extensions and ramifications but was poor in depth orientation.

Conclusion

MRI is a reliable diagnostic modality in the evaluation of peri-anal fistulas. Post contrast T1 SPGR sequence with its high resolution images and excellent anatomical orientation provides almost all the necessary details for accurate evaluation. Although MIP images lack depth orientation their high sensitivity, rotational 2D and 3D capabilities exquisitely depict all the fine ramifications and extensions. The combination of both provides complete evaluation and highest possible diagnostic accuracy aiding successful surgical interventions, aiming to reduce complications and recurrences.     

Prevalence of venous sinus stenosis in Pseudotumor cerebri (PTC) using digital subtraction angiography (DSA)

Objectives

To study the prevalence of intracranial venous stenosis in Pseudotumor cerebri patients.

Patients and methods

Thirty patients were diagnosed having PTC according to Dandy criteria. All underwent general and neurological assessment. Radiological assessment included CT scan brain ±MRI brain without contrast, MRV. All underwent digital subtraction angiography (DSA) (venous phase) to confirm the validity of filling gaps seen at the level of MRV.

Results

MRV brain showed that 24 patients (80%) showed filling gaps. Digital subtraction cerebral angiography (venous phase) showed 9 patients (30%) had stenosis in their dural sinuses. MRV showed to be a good screening tool since it had 100% sensitivity and negative predictive value. However, since it has a moderate specificity (62%) with a positive predictive value (PPV) of only 35%, then lesions detected should be confirmed with digital subtraction cerebral angiography (venous phase) particularly those involving the transverse and sigmoid sinus.

Conclusion

Studying the intracranial venous system in patients with PTC is an important step in understanding the pathophysiology of the disease. Detection of venous sinus stenosis opens the way to a novel therapeutic option for refractory patients like venous sinus stenting.