3D Maximum Intensity Projection Research Articles

MEDS-Net: Multi-encoder based self-distilled network with bidirectional maximum intensity projections fusion for lung nodule detection

Early detection of lung cancer increases cure rates, making precise detection of lung nodules in computed tomography (CT) images crucial. However, creating an accurate computer-aided detection (CADe) system is challenging due to lung structure complexity and nodule heterogeneity. We present a lung nodule detection scheme, inspired by radiologist workflow, fusing CT scan sub-volumes with bidirectional maximum intensity projection (MIP) images within a single architecture. We have developed a novel multi-encoder-based network (MEDS-Net) using self-distillation to learn from three types of inputs: 3D sub-volume, forward, and backward MIP images. MEDS-Net utilizes three encoders to extract insights, passed to the decoder via attention units to suppress redundant features. The decoder employs a self-distillation mechanism, connecting to a distillation block with four auxiliary lung nodule detectors, accelerating convergence and enhancing learning ability. The auxiliary detectors are used during inference to reduce false positives. Our scheme, tested on 888 LIDC-IDRI dataset scans, achieved a 93.6% competition performance metric score, illustrating that fusing bidirectional MIP images with raw CT slices and auxiliary detectors empowers MEDS-Net to accurately detect lung nodules while minimizing false positives.

Differentiation between normal and abnormal kidneys using 99mTc-DMSA SPECT with deep learning in paediatric patients

To investigate the feasibility of using deep learning (DL) to differentiate normal from abnormal (or scarred) kidneys using technetium-99m dimercaptosuccinic acid (99mTc-DMSA) single-photon-emission computed tomography (SPECT) in paediatric patients. Three hundred and one 99mTc-DMSA renal SPECT examinations were reviewed retrospectively. The 301 patients were split randomly into 261, 20, and 20 for training, validation, and testing data, respectively. The DL model was trained using three-dimensional (3D) SPECT images, two-dimensional (2D) maximum intensity projections (MIPs), and 2.5-dimensional (2.5D) MIPs (i.e., transverse, sagittal, and coronal views). Each DL model was trained to determine renal SPECT images into either normal or abnormal. Consensus reading results by two nuclear medicine physicians served as the reference standard. The DL model trained by 2.5D MIPs outperformed that trained by either 3D SPECT images or 2D MIPs. The accuracy, sensitivity, and specificity of the 2.5D model for the differentiation between normal and abnormal kidneys were 92.5%, 90% and 95%, respectively. The experimental results suggest that DL has the potential to differentiate normal from abnormal kidneys in children using 99mTc-DMSA SPECT imaging.

Diagnostic and Practical Value of Abbreviated Contrast Enhanced Magnetic Resonance Imaging in Breast Cancer Diagnostics.

Although MRI is the most efficient method of detecting breast cancer, its standard protocol is time-consuming and expensive. The objective of this study was to compare the diagnostic accuracy of the modified innovative abbreviated MRI protocol (AMRP) and the standard magnetic resonance protocol (SMRP) when detecting breast cancer. The research involved 477 patients referred for breast MRI due to suspected lesions. They were randomly assigned to the AMRP group (N = 232) or the SMRP group (N = 245). The AMRP comprised one native (contrast-free) and four post-contrast dynamic sequences of T1-weighted volume imaging for breast assessment (VIBRANT) and 3d MIP (maximum intensity projection) lasting for eight minutes. All the patients underwent a core biopsy of their lesions and histopathological analysis. The groups were comparable regarding the pre-screening and post-diagnostic characteristics and were of average (±SD) age at breast cancer diagnosis of 53.6 ± 12.7 years. There was no significant difference between the two protocols in terms of specificity or sensitivity of breast cancer diagnosis. The sensitivity (95% Cis) of the AMRP was 99.05% (96.6-99.9%), and its specificity was 59.09% (36.4-79.3%), whereas the sensitivity of the SMRP was 98.12% (95.3-99.5%) and its specificity was 68.75% (50.0-83.9%). Most of the tumors comprised one solid lesion in one of the breasts (77.3%), followed by multicentric tumors (16%), bilateral tumors (4.3%), and multifocal tumors (1.7%). The average size of tumors was approximately 14 mm (ranging from 3 mm to 72 mm). Our innovative AMR protocol showed comparable specificity and sensitivity for the diagnosis of breast cancer when compared to SMRP, which is the "gold standard" for histopathological diagnosis. This can lead to great savings in terms of the time and cost of imaging and interpretation.

PSMA PET tumor-to-salivary glands ratio (PSG score) to predict response to Lu-177 PSMA radioligand therapy: An international multicenter retrospective study.

5043 Background: PSMA-targeted radioligand therapy can improve the outcome of patients with advanced mCRPC. However, patients do not respond uniformly and a PSA decline of ≥50% (PSA50) was achieved only in 46% of the patients in the VISION trial. We hypothesized that using the parotid glands instead of the liver as the reference organ enables more selective stratification. The aim of this study was to test PSMA PET tumor-to-Salivary Glands ratio (PSG score) to predict outcomes after Lu-177 PSMA. Methods: This was an international multicenter retrospective study using the established dataset consisting of 270 men with mCRPC treated with Lu-177 PSMA (Gafita A, Lancet Oncol 2021). First, we assessed baseline PSMA PET quantitatively (qPSG score) to calculate the tumor-to-salivary gland ratio (qPSG = SUVmean whole-body-tumor / SUVmean parotid glands) using a semi-automatic segmentation software (qPSMA). Patients were divided into three groups: high (qPSG > 1.5), intermediate (qPSG = 0.5 - 1.5), and low (qPSG < 0.5). Second, we assessed the reproducibility and the predictive value of the PSG score visually (vPSG score) graded by ten nuclear medicine physicians. Each reader read the baseline PSMA PET 3D maximum intensity projection (MIP) images, and classified the patients into three groups: (high) most of the lesions (> 80%) show higher uptake than parotid glands; (intermediate) neither “low” nor “high”; (low) most of the lesions (> 80%) show lower uptake than parotid glands. In case of disagreement, a majority vote was used. Outcome measures were PSA-progression free-survival (PSA-PFS), overall survival (OS), and PSA50. Results: 237 men were analyzed after excluding 33 men whose parotid glands were out of the scan range. The number of the patients in the high, intermediate, and low groups were 56/237 (23.6%), 163 (68.8%), and 18 (7.6%) for qPSG score, and 106/237 (44.7%), 96 (40.5%), and 35 (14.8%) for vPSG score, respectively. The inter- and intra-readers reproducibility of the vPSG score showed substantial (Fleiss’ weighted Kappa: 0.68) and almost perfect (Cohen's weighted Kappa (mean): 0.83) agreement, respectively. The median PSA-PFS of high, intermediate, and low groups were 7.2, 4.0, and 1.9 months (p < 0.001) for qPSG score and 6.7, 3.8, and 1.9 months (p < 0.001) for vPSG score, respectively. Higher PSA50 rate was observed in the high group followed by the intermediate and low groups (high vs intermediate vs low: [qPSG] 69.6% vs 38.7% vs 16.7%; [vPSG] 63.2% vs 33.3% vs 16.1%). The median OS was longer in the high group than in the intermediate + low (i.e., non-high) group by qPSG (15.0 vs. 11.7 months (p = 0.013)) and vPSG score (14.3 vs.11.0 months (p = 0.038)). Conclusions: The PSG score is a valuable predictive biomarker for response to Lu-177 PSMA. The vPSG score yielded substantial reproducibility and comparable predictive value to the qPSG score.

Predicting the outcome of mCPRC patients after Lu-177 PSMA therapy using semi-quantitative and visual criteria in baseline PSMA PET: An international multicenter retrospective study.

32 Background: The aim of this study was to assess the use of the baseline PSMA parotids uptake as a reference to determine eligibility for Lu-177 PSMA radioligand therapy (RLT) by using semi-quantitative and standardized visual criteria. Methods: We conducted a retrospective cohort study using a multicenter dataset 270 men with mCRPC treated with Lu-177 PSMA (Gafita A, Lancet Oncol 2021). For quantitative analysis, semi-automatic segmentation software (qPSMA) divided men into three groups according to the SUVmean ratio of whole-body-tumor to parotid glands: (high) > 1.5; (intermediate) 0.5 - 1.5; (low) < 0.5. For visual analysis, ten nuclear medicine physicians with (n = 5) and without (n = 5) clinical experience in Lu-177 PSMA RLT ( > 50 cases) read each baseline PSMA PET 3D maximum intensity projection (MIP) images, and classified the patients into three groups: (high) most ( > 80%) of the lesions show higher uptake than parotid glands; (intermediate) neither “low” nor “high”; (low) most ( > 80%) of the lesions show lower uptake than parotid glands. In case of inter-reader disagreement, a majority vote was used. Outcome measures included PSA-progression free-survival (PSA-PFS), overall survival (OS), and PSA decline of ≥50% (PSA50). Fisher’s exact test and Kaplan–Meier analysis with the log-rank test was performed for PSA50 and survival analysis, respectively. Results: 237 men were analyzed after excluding 33 men with more than half of the parotid glands out of the PET scan field-of-view. The number of the patients in the high, intermediate, and low groups were 106/237 (44.7%), 96 (40.5%), and 35 (14.8%) for visual criteria, and 56 (23.6%), 163 (68.8%), and 18 (7.6%) for quantitative analysis, respectively. The inter- and intra-readers reproducibility of the visual scoring showed substantial (Fleiss’ weighted Kappa: 0.68) and almost perfect (Cohen's weighted Kappa (mean): 0.83) agreement, respectively. The median PSA-PFS was 6.7, 3.8, and 1.9 months (p < 0.001); and 7.2, 4.0, and 1.9 months (p < 0.001) in the high, intermediate, and low expression groups by visual and quantitative criteria, respectively. The PSA50 was 63.2%, 33.3%, and 17.1% (p < 0.001), and 69.6%, 38.7%, and 16.7% (p < 0.001) in the high, intermediate, and low expression groups by visual and quantitative criteria, respectively. OS was longer in the high PSMA expression group than in the intermediate + low (i.e., non-high) group by visual (14.3 vs.11.0 months (p = 0.038)) and quantitative criteria (15.0 vs. 11.7 months (p = 0.013)). Conclusions: Tumor-to-parotid uptake using a simple visual or semi-quantitative measure is a valuable prognostic biomarker for response in men with mCRPC treated with Lu-177 PSMA RLT.

DOP13 The Arborisation index: An MRI-based measure of mesenteric hyperaemia in Crohn’s Disease

Abstract Background Robust and sensitive therapeutic targets are key in effective management of Inflammatory Bowel Disease1. Mesenteric hyperaemia is a recognized sign of active disease and in cross-sectional image is described as the comb sign. Although it is subjectively described, no automated quantitative MRI-based measures have been developed. We aim to develop an automated methodology using contrast-less time of flight (TOF) Magnetic resonance angiography (MRA). Methods A MATLAB algorithm was developed to track the vessels on a 3D maximum intensity projection of a TOF MRA data set and calculate an arborization Index which is the number of branching points in the intrabdominal vessels (figure 1). 2D TOF scans were acquired in the transverse plane between the top of the hip joint and L4 vertebra using a 3T Ingenia Wide bore scanner (Philips, The Netherlands). The primary outcome was a comparison of the arborization index between Crohn’s disease (CD) and healthy volunteers (HV) groups. A planned sub-analysis was undertaken across CD and HV matched for BMI to investigate the effect of visceral fat on the arborization index. Repeated measures were undertaken to evaluate the variability of the quantification method. No contrast agents were used for the TOF MRA scans. Biological variations within each group and test-retest repeatability were assessed using the coefficient of variation (CV). Statistical analysis with unpaired, two-tailed t-tests were conducted and differences were considered significant when the p-value ≤0.05. All absolute values are presented as mean ±standard deviation (SD). Results In this prospective pilot study, 7 CD patients (C-Reactive Protein=5.2±6.1 mg/L, Faecal Calprotectin 611±981μg/g, BMI=23±3 kg/m2) and 15 HVs (BMI=29±7 kg/m2) were recruited. Patients showed a significantly higher arborization index when compared to HVs (mean arborization in HV=94±21 and CD=139±26; p-value=0.002). The difference in arborization index persisted in a sub-analysis of 7 HVs (BMI=24±2 kg/m2) and 7 CD patients (mean arborization in matched HVs=101±22 vs mean index in CD=139±26; p=0.01) (Figure 2). The CV was 23% for HVs and 18% for CD indicating biological variation. Test-retest variability calculated from multiple TOF scans of the same subjects gave a mean CV of 6±5% for both groups combined. Conclusion Our preliminary data suggest that the arborization index may be a useful measure of hypervascularity and hence intestinal inflammation in Inflammatory Bowel Disease. Further validation to standard disease activity measures is needed across larger cohorts to better investigate the utility of this potential biomarker as a non-invasive measure of disease activity and its reversibility to IBD therapies. Reference 1.Turner,D.,et al.Gastro.2021;160(5):1570–1583.

A preliminary investigation of re-evaluating the irradiation dose in hepatocellular carcinoma radiotherapy applying 4D CT and deformable registration.

PurposeTo investigate the effect of breathing motion on dose distribution for hepatocellular carcinoma (HCC) patients using four‐dimensional (4D) CT and deformable registration.MethodsFifty HCC patients who were going to receive radiotherapy were enrolled in this study. All patients had been treated with transarterial chemoembolization beforehand. Three‐dimensional (3D) and 4D CT scans in free breathing were acquired sequentially. Volumetric modulated arc therapy (VMAT) was planned on the 3D CT images and maximum intensity projection (MIP) images. Thus, the 3D dose (Dose‐3D) and MIP dose (Dose‐MIP) were obtained, respectively. Then, the Dose‐3D and Dose‐MIP were recalculated on 10 phases of 4D CT images, respectively, in which the end‐inhale and end‐exhale phase doses were defined as Dose‐3D‐EI, Dose‐3D‐EE, Dose‐MIP‐EI, and Dose‐MIP‐EE. The 4D dose (Dose‐4D‐3D and Dose‐4D‐MIP) were obtained by deforming 10 phase doses to the end‐exhale CT to accumulate. The dosimetric difference in Dose‐3D, Dose‐EI3D, Dose‐EE3D, Dose‐4D‐3D, Dose‐MIP, Dose‐EIMIP, Dose‐EEMIP, and Dose‐4D‐MIP were compared to evaluate the motion effect on dose delivery to the planning target volume (PTV) and normal liver.ResultsCompared with Dose‐3D, PTV D99 in Dose‐EI3D, Dose‐EE3D and Dose‐4D‐3D decreased by an average of 6.02%, 1.32%, 2.43%, respectively (P < 0.05); while PTV D95 decreased by an average of 3.34%, 1.51%, 1.93%, respectively (P < 0.05). However, CI and HI of the PTV in Dose‐3D was superior to the other three distributions (P < 0.05). There was no significant differences for the PTV between Dose‐EI and Dose‐EE, and between the two extreme phase doses and Dose‐4D (P> 0.05). Negligible difference was observed for normal liver in all dose distributions (P> 0.05).ConclusionsFour‐dimensional dose calculations potentially ensure target volume coverage when breathing motion may affect the dose distribution. Dose escalation can be considered to improve the local control of HCC on the basis of accurately predicting the probability of radiation‐induced liver disease.

Slice-stacking T2-weighted MRI for fast determination of internal target volume for liver tumor.

To investigate the feasibility of generating maximum intensity projection (MIP) images to determine internal target volume (ITV) using slice-stacking MRI (SS-MRI) technique. Slice-stacking is a technique which applies a multi-slice MRI acquisition to generate a 3D MIP for ITV contouring, without reconstructing 4D-MRI. 4D digital extended cardiac-torso (XCAT) phantom was used to generate MIP images with sequential 2D HASTE sequence, with different tumor diameters (10, 30 and 50 mm) and with simulated regular and irregular (patient) breathing motions. A reference MIP was generated using all acquisition images. Consecutive repetitions were then used to generate MIP to analyze the relationship between Dice's similarity coefficient (DSC) and the number of repetitions, and the relationship between the relative ITV volume difference and the number of repetitions. Images from XCAT phantom and from three hepatic carcinoma patients were collected in this study to demonstrate the feasibility of this technique. For both regular and irregular breathing motion, the average DSC of ITV is >0.94 and the average relative ITV volume difference is <10% (approximately 0.15 cm3) when using 5 repeated scanning images to reconstruct MIP for tumor diameter of 10 mm. As tumor diameter increases, the DSC of ITV is >0.97 and the relative ITV volume difference is <5% for regular breathing motion, and the DSC of ITV is >0.97 and the relative ITV volume difference is <5.5% for irregular breathing motion when using 5 repeated scanning images to reconstruct MIP. In patient image study, the mean relative ITV volume difference is <3% and the mean DSC is 0.99 when using 5 repeated scanning images to reconstruct MIP. The number of scans required to generate tumor ITV for slice-stacking method (5-7 repetition) is 3-4 times less than that of 4D-MRI (15-20 repetitions). It is feasible to generate a fast clinically acceptable ITV using slice-stacking method with sequential 2D MR images.

Role of magnetic resonance venography in the evaluation of cerebral venous thrombosis in a tertiary care hospital in rural Tamil Nadu

Background: Cerebral venous sinus thrombosis (CVST) is a common medical problem in India which has serious clinical consequences. MR venographic technique is one of the modalities of choice for diagnosis and evaluation of dural sinus and cerebral venous thrombosis wherever MRI facility is available. The present study was conducted to evaluate the spectrum of magnetic resonance venography in the diagnosis of cerebral venous sinus thrombosis. Material and Methods: It was a record-based study, in which case records of CVST patients who attended the department of radiodiagnosis was reviewed. Total cases included were 30 over the period of 2 years. A complete clinical history of patients followed by general physical examination and detailed central nervous system with examination of other significant system was done. Non contrast MR imaging including T1 sagittal, T2 axial, Fluid Attenuated Inversion Recovery (FLAIR) coronal, axial diffusion weighted images(DWI), Susceptibility weighted images (SWI), 3D T1 Fast field echo (FFE), 2D Time of Flight (TOF) Source images and 3D maximum intensity projection(MIP) images were acquired and evaluated for presence of venous thrombosis as indicated. Data analysis was done. Results: The results of the study showed that the incidence of CVST was more in female population. The peak incidence of CVST was found in the age group of 21 to 40 years. Headache was the commonest clinical feature seen in 09 patients (30%). The superior sagittal sinus is commonly involved in CVST, which is seen in 19 patients (63.33%), the next commonest sinus involved is right transverse sinus in 10 patients (33.3%) followed by right sigmoid sinus in 09 patients (30.0%). Conclusion: This study concluded that MRI and MRV are valuable imaging modalities for the diagnosis of CVST. MRI and non contrast MRV should be recommended as they are safer, non-invasive, non-ionizing and highly accurate modalities.

Distribution of Medial Calcification and Luminal Stenosis in Symptomatic Patients with Hemodialysis and Peripheral Artery Disease Using 3D Computed Tomography Angiography

Background: Vascular calcification, including medial and intimal calcification leading to luminal stenosis of the lower extremities are commonly associated with hemodialysis (HD), whereas their distribution has not been assessed comprehensively. Three-dimensional (3D) computed tomography angiography (CTA) may be a powerful imaging tool for detection of vascular calcification and arterial stenosis with high spatial resolution in HD patients and peripheral artery disease (PAD). Objectives: The aim of this study was to investigate the distribution of medial calcification and luminal stenosis in symptomatic patients with HD and PAD using 3D CTA. Patients and Methods: Forty-seven patients with HD and symptomatic PAD underwent 3D CTA of the lower extremities. We used 3D maximum intensity projection with and without subtraction by precontrast from postcontrast images in order to assess the medial calcification and luminal stenosis in the common, external, and internal iliac arteries, superficial femoral arteries, and lower limb arteries. Results: The external iliac artery (EIA) was significantly spared from both medial calcification and luminal stenosis, while the internal iliac, superficial femoral artery (SFA), and tibioperoneal arteries had either arterial disorders. Conclusion: The characteristic distribution of medial calcification and luminal stenosis, such as spared EIA and SFA involvement, is observed in patients with HD and symptomatic PAD by 3D CTA.

Comparison of Morphology of Intracranial Aneurysms on Computed Tomography Angiography with Digital Subtraction Angiography and Intraoperative Findings– A Single Centre Experience

Introduction: Multi-Detector Computed Tomography (MDCT) angiography is a non-invasive technique in emergency screening of Subarachnoid Haemorrhage (SAH) for accurately detecting aneurysms. Digital Subtraction Angiography (DSA) remains the gold standard for diagnosis of intracranial aneurysm. Computed Tomography Angiography (CTA) is being increasingly used for this purpose and can presently replace DSA as the most reliable means to detect intracranial aneurysms in SAH. Aim: To characterise the morphology of intracranial aneurysms with CTA and to compare it with DSA and intraoperative findings. Materials and Methods: This analytical study includes patients suspected to have intracranial aneurysm and underwent CTA on 16 slice MDCT scanner. Post-processing Multiplanar Reconstructions (MPR), 3D Volume Rendering (VR) and Maximum Intensity Projection (MIP) were performed. The findings of CTA findings were compared with DSA and intraoperative/indocyanine angiography images obtained by Leica neurosurgical operating microscope, wherever possible. Morphological parameters: size (dome, neck, height, dome to neck ratio, aspect ratio in saccular and length, diameter in fusiform), shape, lobulation, tit, location, thrombosis/ calcification, blood vessels arising, ruptured or not, grade of SAH (modified CT Fischer score) and vasospasm (grade, number/location of vasospastic segments) were assessed and compared with DSA and intraoperative findings. Results: In 71 patients, 97 intracranial aneurysms were studied. Saccular aneurysm was the most common and anterior communicating artery (ACOM) was the most common location. Significant correlation of dome: neck and aspect ratios between CTA and DSA (p=0.0089) was noted. The sensitivity, Positive Predictive Value (PPV) and accuracy of CTA for aneurysm >3 mm was 100%. Two aneurysms <3 mm were missed on CTA, but detected by DSA. Therefore, for aneurysms <3 mm in size, sensitivity was 92.86%, with a PPV and accuracy of 96.3% and 89.66%, respectively. Overall sensitivity of CTA irrespective of size was 97.9%, with 97.9% PPV and 95.9% accuracy was observed. Conclusion: MDCTA with 3D reconstructions and volume rendering is the ideal first line imaging modality in non-traumatic SAH for detection of aneurysm with a high degree of accuracy. DSA can be used to diagnose tiny aneurysms <3 mm if missed on CTA, if there is a high degree of suspicion.

Visualization of Inflammation at Early Stage of Lung Cancer in Xenografted Temporally Immunosuppression Rats by Ferrioxamine Magnetic Resonance Imaging.

Physiological responses such as chronic inflammation and angiogenesis could be used as biomarkers for early detection of cancer with noninvasive imaging modalities. The present study reports the application of magnetic resonance imaging instrument to image the binding of ferrioxamine with hemin that allows visualizing the chronic inflammation foci of lung tissue of immunocompromised rats xenografted using small cell lung carcinoma. A low concentration of ferrioxamine (0.05 ± 0.02 μM·kg−1 of rat weight) deposited on tissue outside the vasculature was found to diffuse across the capillary walls to the interstitial space and inflammation foci, which provided a clear enhancement of T1-weighted gradient-echo sequence images. Ferrioxamine imaging allowed the determination of inflammatory sites and their localization in 3D fat-suppressed maximum intensity projections. The smallest dimension of foci that can be clearly determined is about 0.1 mm3. In concomitant to the in vivo imaging, analysis of histological tissue section showed the development of inflammatory sites. This study provides evidence that medical imaging instrument such as MRI scanner allows researchers to correlate images taken with MRI with those using high-resolution microscopy. Moreover, ferrioxamine is a useful molecular probe for determining chronic inflammation particularly at the very early stages of cancer.

Delayed intravenous contrast-enhanced 3D FLAIR MRI in Meniere’s disease: correlation of quantitative measures of endolymphatic hydrops with hearing

ObjectiveUsing three-dimensional fluid-attenuated inversion recovery magnetic resonance imaging (3D-FLAIR MRI), our goal was to correlate quantifiable measures of endolymphatic hydrops (EH) with auditory function in the setting of Meniere’s disease (MD). Materials and methodsForty-one ears were analyzed in 21 subjects (12 ears with MD, 29 without MD). Vestibular endolymphatic space size measurements obtained with two different techniques were referenced against clinical data. ResultsEH was better evaluated on 3D maximum intensity projections (MIPs) than on two-dimensional (2D) images. Using MIPs, quantitative assessments EH correlated with severity of hearing impairment. Conclusion3D MIPs were superior to 2D images for evaluating EH in the setting of MD.

Comparison of 3D Maximum intensity projection (MIP) reconstruction and 2D T2 Half-Fourier Acquisition Single-Shot Turbo Spin-Echo (HASTE) sequence in magnetic resonance cholangiopancreatography

Introduction: Magnetic resonance cholangiopancreatography (MRCP) is a method that allows noninvasive visualization of pancreatobiliary tree and does not require contrast application. It is a modern method based on heavily T2-weighted imaging (hydrography), which uses bile and pancreatic secretions as a natural contrast medium. Certain weaknesses in quality of demonstration of pancreatobiliary tract can be observed in addition to its good characteristics. Our aim was to compare the 3D Maximum intensity projection (MIP) reconstruction and 2D T2 Half-Fourier Acquisition Single-Shot Turbo Spin-Echo (HASTE) sequence in magnetic resonance cholangiopancreatography.Methods: During the period of one year 51 patients underwent MRCP on 3T „Trio“ system. Patients of different sex and age structure were included, both outpatient and hospitalized. 3D MIP reconstruction and 2D T2 haste sequence were used according to standard scanning protocols.Results: There were 45.1% (n= 23) male and 54.9% (n=28) female patients, age range from 17 to 81 years. 2D T2 haste sequence was more susceptible to respiratory artifacts presence in 64% patients, compared to 3D MIP reconstruction with standard error (0.09), result significance indication (p=0.129) and confidence interval (0.46 to 0.81). 2D T2 haste sequences is more sensitive and superior for pancreatic duct demonstration compared to 3D MIP reconstruction with standard error (0.07), result significance indication (p=0.01) and confidence interval (0.59 to 0.87)Conclusion: In order to make qualitative demonstration and analysis of hepatobiliary and pancreatic system on MR, both 2D T2 haste sequence in transversal plane and 3D MIP reconstruction are required.

Application of a novel metal artifact correction algorithm in flat-panel CT

Ziele: To evaluate the possibilities in applying a novel algorithm to correct for beam hardening artifacts caused by metal implants in computed tomography performed on a flat panel equipped c-arm angiography system (FP-CT). Methode: 35 datasets of cerebral FP-CT acquisitions (XperCT, Allura Xper FD 20/20, Philips) with present implants (32 patients; 27 FP-CT after coil-embolization; 8 after aneurysm clipping, these with intravenous application of contrast media) have been reconstructed applying smooth (soft tissue) and sharp (implant) kernels with and without a novel reconstruction filter for metal artifact correction, resulting in high-resolution isotropic datasets (edge length: 0.15 mm for sharp kernel and 0.3 mm for smooth kernel, respectively). Image viewing was performed in multiplanar reformations (MPR) in both average and maximum intensity projection (MIP) mode, sharp kernel images additionally in 3D MIP and 3D volume rendering (VR) on a dedicated radiological workplace (PACS IW, GE). Two independent radiologists performed image rating following a defined scale in direct comparison of the image data with and without metal artifact correction, weighted kappa statistics were calculated. Ergebnis: Inter-rater agreement was at least substantial in all regards. Soft tissue image quality at the level of the implants was substantially improved; the additional metal artifact correction algorithm did not induce relevant falsification of the data. In addition, two factors were identified to be having an influence on the quality of the results: Firstly, volume/amount of the implants; secondly, orientation of a non-spherical implant relatively to the plane of acquisition. Schlussfolgerung: Adding metal artifact correction to FP-CT may in future help to spread the applicability of this technique, especially regarding non-invasive follow-up after clipping or coil embolization of intracranial aneurysms with FP-CT with intravenous application of contrast media.

DYNAMIC MRI FOR TUMOR ENHANCEMENT: AN EXPERIMENTAL BREAST CANCER MODEL

Dynamic contrast-enhanced magnetic resonance imaging (MRI) with post-processing is routinely used for the analysis of tumors. However, although breast MRI has gained broad clinical recognition, the relationship between imaging findings and tumor pathogenesis has yet to be fully elucidated. We grafted tumors on rats, to examine dynamic MRI images of the tumors, using post-processing subtraction with 3D maximum intensity projection (sMIP). We established a preliminary platform for analysis to compare hemodynamic-based images with histopathological findings and to further biomolecular research. This platform could facilitate future research on the mechanisms of breast tumor enhancement using MRI, improvements to MRI analysis and reduction of the false positive rate, and the development of novel drugs and contrast media.

Application of 4D-CTA using 320-row area detector computed tomography on spinal arteriovenous fistulae: initial experience

Time-resolved computed tomography angiography (4D-CTA) using a 320-row area detector CT scanner has recently been applied in the evaluation of cranial vascular disorders. However, application of 4D-CTA to spinal vascular disorder evaluation has never before been described. The authors herein report their initial experience of 4D-CTA in the evaluation of spinal arteriovenous fistulas (AVFs) and compare this novel modality with other imaging modalities. Four consecutive patients with spinal AVF underwent time-resolved contrast-enhanced magnetic resonance angiography (trMRA), 4D-CTA, and selective catheter angiography (CA). In 4D-CTA, volume data was transformed into 3D volume-rendered images and maximum intensity projection. These images were also evaluated by time-resolved serial phases. Then, images of each modality were compared, focusing on the detection of perimedullary draining veins and the prediction of AVF location and drainage flow direction. All modalities successfully detected perimedullary draining veins in all cases. Location of the AVF was detected in all cases by CA. trMRA and 4D-CTA detected the AVF in three out of the four cases. With regard to flow direction, while 4D-CTA successfully depicted ascending or descending drainage flow in the spinal canal, CA failed to detect the flow direction in one case while trMRA failed in two cases. In the case with epidural AVF, 4D-CTA was the only technique to detect the flow direction of perimedullary drainage. Although this is only an initial experience of the application of 4D-CTA to spinal vascular diseases, 4D-CTA was capable of detecting the dynamic vascular flow of spinal AVFs. The authors believe that 4D-CTA can be a useful option in the evaluation of spinal AVFs.

Assessment of ureteric obstruction with 16-MDCT: Curved planar reformats versus three-dimensional volume-rendered images and their corresponding maximum intensity projections

AimTo compare the sensitivity and diagnostic accuracy of curved planar reformation (CPR) image on the one hand versus combined volume-rendered (VR) image and its corresponding maximum intensity projection (MIP) image on the other hand for determination of the cause and level of ureteral obstruction. Materials and methodsThe study included 60 patients with clinical and sonographic manifestations of ureteral obstruction who underwent two-phase multidetector CT urography (MDCTU) using a 16-slice machine. A total of 82 ureters were examined. CPR images were performed to display the entire course of ureters in the same image. 3D VR reformats and their corresponding MIP were used to enhance visualization of opacified ureters. The sensitivity and accuracy of CPR, and combined 3D VR and MIP for diagnosis of ureteral obstruction were calculated and compared in reference to the gold standard. ResultsThe cause of ureteral obstruction was calculous in 28/82 ureters (34.14%), and noncalculous in 50/82 (61%). The lower third ureter was the most affected level in 48/82 ureters (58.5%). The total sensitivity and accuracy of CPR for the cause of the ureteric obstruction (97.5% and 95.3%, respectively) were higher than those of 3D VR and its corresponding MIP (75% and 73.2%, respectively). CPR also was more sensitive and accurate (total sensitivity of 100% and accuracy of 100%) compared with those of combined 3D VR and its corresponding MIP (79.5% and 75.9%, respectively) for the level of ureteral obstruction. ConclusionsCPR had superior diagnostic accuracy than 3D VR and MIP in detecting the cause and level of ureteral obstruction.

Morphological features and clinical feasibility of thoracic duct: Detection with nonenhanced magnetic resonance imaging at 3.0 T

To evaluate the detection of the thoracic duct using nonenhanced magnetic resonance imaging (MRI) and to determine the influence of some related disorders on the lymphatic duct. Highly fluid-sensitive sequence and fat-suppressed T2-weighted imaging (FS-T2WI) were performed in a total of 139 cases. The axial and coronal images were used to locate the thoracic duct and the measurement and evaluation of its dimensions were performed using a 3D maximum intensity projection (MIP) reconstruction image. The differences in the dimensions among control, portal hypertension, and common bile duct obstruction groups were compared using one-way analysis of variance. The cisterna chyli was shown in 91% of cases on FS-T2WI, while the thoracic duct appeared in 70% of the MIP images. The common configuration of the cisterna chyli was tubular or saccular in 73%. Eighty thoracic ducts had a slight turn declining to the left at the level of T8-10. There was a significant difference in the transverse diameter of the thoracic duct between the portal hypertension group and other groups (F = 5.638, P = 0.005). Nonenhanced MRI is feasible for locating and depicting the morphological features of the thoracic duct. Portal hypertension may influence the dimension of the thoracic duct.

SU‐GG‐J‐142: Investigation of MIP PET in Motion‐Encompassing Methods to Account for Respiratory Motion in Radiotherapy

Purpose: Radiation treatment planning with PET/CT has been shown to be beneficial and leads to smaller variations in target delineation than using CT only. This study investigates the 3D maximum intensity projection (MIP) PET images derived from respiratory‐gated 4D PET as a complement to the MIP CT derived from a 4D CT dataset and their use in treatment planning as a means to account for respiratory motion in free‐breathing radiotherapy for lung and abdomen tumors. Methods and materials: 21 PET/CT patient datasets with 31 lesions were acquired. The patient respiratory motion was monitored by the Real‐time Position Management system. PET listmode data were phase‐binned into 5 frames and reconstructed. 3D MIP PET images were derived from the 5‐bin 4D PET datasets. Tumor volumes were determined by an automatic segmentation method and compared for the MIP PET and static PET images. The tumor motion amplitude was determined by measuring the centroid in phase‐gated images. The impact of tumor size and motion amplitude were investigated. In addition, PET data were binned into 10 frames to study the noise change in MIP PET. The comparison between the MIP PET and MIP CT is under study. Results: Compared to static PET, the tumor volumes in the MIP PET increased by 10% 14%, with a maximum increase of 44%. The volume increases are larger for the smaller tumors sizes and larger motion amplitudes. The image noise of the MIP PET is higher than in static PET and increases with number of phase bins. Conclusion: The MIP PET has a potential to complement MIP CT to inform the radiation treatment planning for motion‐encompassing radiotherapy by accounting for respiratory motion.