Automated cleaning of tie point clouds following USGS guidelines in Agisoft Metashape professional (ver. 2.1.0).

The U.S. Geological Survey (USGS) has published a guideline to improve the quality of digital photogrammetric reconstructions created with the widely used Agisoft Metashape Professional software. The suggested workflows aim at filtering out low-quality tie points from the tie point cloud to optimize the camera model. However, the optimization procedure relies on an iteratively performed trial-and-error approach. If manually performed, the time expenditure required from the operator can be significant and the optimization process can be affected by the degree of diligence that is applied. To minimize the time expenditure and attentiveness required from the operator and to provide a framework for an improved reproducibility of camera model optimization workflows, we present here a python script serving as an extension for Agisoft Metashape Professional (tested on version 2.1.0) that automatizes the iterative point filtering procedure proposed by the USGS. As a result, the entire processing cycle can be performed largely unattended. •A graphical user interface allows to individually adjust important camera model optimization parameters.•Main tie point cloud quality measures can be directly assessed.•The reproducibility of the automated camera model optimization as tested in this study generally is above 99%.

Detection of Reduced Diameter of the Cochlear Nerve in Long-term Deaf Patients Quantified With Semiautomatic Measurement of Nerve Cross-sectional Area Using 3T MRI Data.

Hypothesis: High-resolution parallel transmit T2 sampling perfection with application optimized contrast using different flip angle evolution sequence with improved edge discrimination and semiautomatic determination of nerve cross-sectional area (CSA) can be used to evaluate nerve degeneration in the inner auditory canal (IAC) in long-term deaf patients. Background: In patients with hearing loss, temporal bone MRI is routinely acquired to evaluate the morphology of the nerves within the IAC. Earlier studies have shown that the diameter of the cochlear nerve can be used as prognostic marker for the auditory performance after cochlear implantation in postlingually deaf patients. Methods: Eighty-two consecutive MRI scans were analyzed using a semiautomatic tool to measure CSA of cranial nerves in the IAC. Results were correlated with patient history and audiology testing as well as with age and gender. Results: There was a significant reduced CSA of the cochlear nerve in ears with moderate-to-profound hearing loss and deafness compared with ears with normal hearing, but no significant difference in ears with mild-to-moderate hearing loss compared with normal hearing. In detail, normal hearing ears had a CSA of 1.23 ± 0.11 mm2, whereas ears with pantonal hearing loss of more than 40 dB had 1.02 ± 0.05 mm2 (P = 0.026). Maximal CSA of the facial nerve was not different among all groups (average, 1.04 mm2 ± 0.03; linear regression, P = 0.001) and stable with age. However, vestibular nerve CSA decreased significantly with age (average, 1.78 ± 0.05 mm2; linear regression, P = 0.128). Conclusions: In long-term deaf patients, smaller the diameter of cochlear nerve is the more severe the hearing loss is. The new semiautomatic tool can primarily be used to assess nerve diameter and possibly determine ears with nerve degeneration.

Morphometric magnetic resonance imaging (MRI) postprocessing in MRI-negative patients with first unprovoked seizure.

OBJECTIVE: The aim of the study was to evaluate the benefits of morphometric magnetic resonance imaging (MRI) postprocessing in patients presenting with a first seizure and negative MRI results and to investigate these findings in the context of the clinical and electroencephalographic data, seizure recurrence rates, and epilepsy diagnosis in these patients. METHODS: We retrospectively reviewed 97 MRI scans of patients with first unprovoked epileptic seizure and no evidence of epileptogenic lesion on clinical routine MRI. Morphometric Analysis Program (MAP; v2018), automated postprocessing software, was used to identify subtle, potentially epileptogenic lesions in the three-dimensional T1-weighted MRI data. The resulting probability maps were examined together with the conventional MRI images by a reviewer who remained blinded to the patients' clinical and electroencephalographical data. Clinical data were prospectively collected between February 2018 and May 2023. RESULTS: Among the apparently MRI-negative patients, a total of 18 of 97 (18.6%) showed cortical changes suggestive of focal cortical dysplasia. Within the population with positive MAP findings (MAP+), seizure recurrence rates were 61.1% and 66.7% at 1 and 2 years after the first unprovoked seizure, respectively. Conversely, patients with negative MAP findings (MAP-) had lower seizure recurrence rates of 27.8% and 34.2% at 1 and 2 years after the first unprovoked seizure, respectively. Patients with MAP+ findings were significantly more likely to be diagnosed with epilepsy than those patients with MAP- findings (χ2 [1, n = 97] = 14.820, p < .001, odds ratio = 21.371, 95% CI = 2.710-168.531) during a mean follow-up time of 22.51 months (SD = 16.7 months, range = 1-61 months). SIGNIFICANCE: MRI postprocessing can be a valuable tool for detecting subtle epileptogenic lesions in patients with a first seizure and negative MRI results. Patients with first seizure and MAP+ findings had high seizure recurrence rates, meeting the criteria for beginning epilepsy.

Flat panel CT versus multidetector CT in skull base imaging: are there differences in image quality?

BACKGROUND: Purpose of this study was to compare image quality of the skull base in standard 20s protocol flat panel computed tomography (FPCT) with the new time and dose improved 10s protocol as well as with 128 slice multidetector computed tomography (MDCT). METHODS: 10 whole skull preparations were scanned with either 128 slice MDCT(SOMATOM Definition AS+, Siemens, Erlangen) or FPCT (AXIOM-Artis, Siemens, Erlangen) using 10s or 20s protocol. RESULTS: FPCT provides significantly better image quality and improved delimitation of clinically relevant structures in the anterior, temporal and posterior skull base compared to 128 slice MDCT. The 20s FPCT protocol yielded best delimitability of evaluated skull base structures. However, the shorter, dose saving 10s FPCT protocol was still significantly superior to 128 slice MDCT regarding delimitability of skull base structures and additionally showed no significant inferiority compared with the 20s FPCT protocol. CONCLUSIONS: The 10s FPCT protocol yields a significantly better image quality at a comparable radiation dose exposure in imaging skull base structures compared to MDCT. TRIAL REGISTRATION: 371/2017BO2.

Implementation and Assessment of a Laparotomy-Assisted Three-Port Fetoscopic Spina Bifida Repair Program.

Open spina bifida (OSB) is a congenital, non-lethal malformation with multifactorial etiology. Fetal therapy can be offered under certain conditions to parents after accurate prenatal diagnostic and interdisciplinary counseling. Since the advent of prenatal OSB surgery, various modifications of the original surgical techniques have evolved, including laparotomy-assisted fetoscopic repair. After a two-year preparation time, the team at the University of Giessen and Marburg (UKGM) became the first center to provide a three-port, three-layer fetoscopic repair of OSB via a laparotomy-assisted approach in the German-speaking area. We point out that under the guidance of experienced centers and by intensive multidisciplinary preparation and training, a previously described and applied technique could be transferred to a different setting.

Morphometric correlates in patients with functional seizures with and without comorbid epilepsy.

OBJECTIVE: Functional seizures (FS) or psychogenic, non-epileptic seizures (PNES) are episodic alterations of behaviour with similar semiology to epileptic seizures but which are not caused by epileptic brain activity. Epilepsy patients show a high risk in developing FS; therefore, the purpose of this study is to examine morphometric correlates in patients with FS as well as in epilepsy patients with FS by comparing them separately to healthy controls (HC). METHODS: Twenty-one clinical three-dimensional (3D) T1-magnetic resonance imaging (MRI) scans of patients with FS (FS group) and 15 patients with FS and epilepsy (EFS group) were retrospectively compared with one control group of 21 age- and gender-matched HC. Two separate general linear model analyses were conducted via FreeSurfer version 6.0. RESULTS: The study population consisted of 21 FS patients (66.7% females, n = 14) with a median age at the time of the scan of 24 years (range 17-44 years); 15 EFS patients (80% females, n = 12) with a median age at the time of the scan of 27 years (range 16-43 years); and 21 healthy subjects (66.7% females, n = 14) with a median age at the time of the scan of 24 years (range 19-38 years). Both patient groups showed an increased Cth in the right prefrontal lobe: in the FS group in the right superior frontal, rostral middle frontal gyri and the right orbitofrontal cortex and, in the EFS group, in the right superior frontal gyrus and the right orbitofrontal cortex. Decreases in Cth were present in the right lateral occipital lobe in the FS group, while also in both hemispheres in the EFS group, namely the left paracentral, superior frontal, caudal middle frontal, lateral occipital and right superior frontal gyri. Neither group showed changes in curvature. CONCLUSION: These results suggest alterations in regions of emotional processing and executive control in patients with FS regardless of the presence of epilepsy.

Temporal encephaloceles and coexisting epileptogenic lesions.

OBJECTIVE: This study was performed to identify coexisting structural lesions in patients with epilepsy and known temporal encephaloceles (TEs). METHODS: Forty-seven structural magnetic resonance imaging (MRI) scans of patients with epilepsy and radiologically diagnosed TEs were retrospectively reviewed visually and using an automated postprocessing software, the Morphometric Analysis Program v2018 (MAP18), to depict additional subtle, potentially epileptogenic lesions in the 3D T1-weighted MRI data. All imaging findings were evaluated in the context of clinical and electroencephalographical findings. RESULTS: The study population consisted of 47 epilepsy patients (38.3% female, n = 18). The median age at the time of the scan was 40 years (range 12-81 years). Twenty-one out of 47 MRI scans (44.7%) showed coexisting lesions in the initial MRI evaluation; in 38.3% (n = 18) of patients, those lesions were considered probably epileptogenic. After postprocessing, probable epileptogenic lesions were identified in 53.2% (n = 25) of patients. Malformations of cortical development had initially been reported in 17.0% (n = 8) of patients with TEs, which increased to 38.3% (n = 18) after postprocessing. TEs and other epileptogenic lesions were considered equally epileptogenic in 21.3% (n = 10) of the cases in the initial MR reports and 25.5% (n = 12) of the cases after postprocessing. SIGNIFICANCE: Temporal encephaloceles are a potential cause of MRI-negative temporal lobe epilepsy. According to our data, TEs can occur with other lesions, suggesting that increased awareness is also required in patients with lesional epilepsy. TEs may not always be epileptogenic; hence, their occurrence with other structural pathologies may influence the presurgical evaluation and surgical approach. Finally, TEs can be associated with malformations of cortical development, which may indicate a common developmental etiology of those lesions.

[The Complexity of SARS-CoV-2 Infection in the Clinical Setting of Obstetrics - Discussion Based on a Case Study]. / Die Komplexität der SARS-CoV-2-Infektion im klinischen Alltag der Geburtshilfe ­ Auseinandersetzung anhand eines Fallbeispiels.

Since the beginning of the pandemic, SARS-CoV-2 infection has dominated clinical practice. In the treatment of high-risk populations, there has long been uncertainty about the extent and consequences of infection. This high-risk population includes pregnant patients. The establishment of clinical registry studies was able to contribute an assessment of the pandemic situation for this collective within a very short time and with enormous effort. Based on a clinical case, the following report describes the association between SARS-CoV-2 infection of a pregnant patient with clinical signs of preeclampsia to the development of posterior reversible encephalopathy syndrome (PRES). Based on the case, the differential diagnostic workup between fulminant course of infection and preeclampsia is presented. The article presents the current data on the occurrence of PRES in pregnancy in the context of SARS-CoV-2 infection and addresses possible differential diagnoses. Interdisciplinary care of the patient allows an overview of aspects of each specialty to be presented.

Temporal encephaloceles in epilepsy patients and asymptomatic cases: Size may indicate epileptogenicity.

OBJECTIVE: This study was undertaken to identify temporal encephaloceles (TEs) and examine their characteristics in patients with temporal lobe epilepsy (TLE) and extratemporal lobe epilepsy (ETLE), as well as in asymptomatic cases. METHODS: Four hundred fifty-eight magnetic resonance imaging scans were examined retrospectively to identify TE in 157 patients with TLE, 150 patients with ETLE, and 151 healthy controls (HCs). RESULTS: At least one TE was identified in 9.6% of the TLE patients (n = 15, 95% confidence interval [CI] = 5.3%-15.3%), in 3.3% of patients with ETLE (n = 5, 95% CI = 1.1%-7.6%), and in 2.0% of the HCs (n = 3, 95% CI = .4%-5.7%), indicating a significantly higher frequency in patients with TLE compared to ETLE and HC subjects (p = .027, p = .005). Examining the characteristics of TEs in both asymptomatic and epilepsy patients, we found that TEs with a diameter of less than 6.25 mm were more likely to be asymptomatic, with a sensitivity of 91.7% and a specificity of 73.3% (area under the curve = .867, 95% CI = .723-1.00, p = .001). SIGNIFICANCE: Temporal encephaloceles may occur without presenting any clinical symptoms. Patients with TLE show a higher frequency of TEs compared to the ETLE and HC groups. According to our study, TE size could be used to suggest potential epileptogenicity.

Harnessing Real-World Data to Inform Decision-Making: Multiple Sclerosis Partners Advancing Technology and Health Solutions (MS PATHS).

Background: Multiple Sclerosis Partners Advancing Technology and Health Solutions (MS PATHS) is the first example of a learning health system in multiple sclerosis (MS). This paper describes the initial implementation of MS PATHS and initial patient characteristics. Methods: MS PATHS is an ongoing initiative conducted in 10 healthcare institutions in three countries, each contributing standardized information acquired during routine care. Institutional participation required the following: active MS patient census of ≥500, at least one Siemens 3T magnetic resonance imaging scanner, and willingness to standardize patient assessments, share standardized data for research, and offer universal enrolment to capture a representative sample. The eligible participants have diagnosis of MS, including clinically isolated syndrome, and consent for sharing pseudonymized data for research. MS PATHS incorporates a self-administered patient assessment tool, the Multiple Sclerosis Performance Test, to collect a structured history, patient-reported outcomes, and quantitative testing of cognition, vision, dexterity, and walking speed. Brain magnetic resonance imaging is acquired using standardized acquisition sequences on Siemens 3T scanners. Quantitative measures of brain volume and lesion load are obtained. Using a separate consent, the patients contribute DNA, RNA, and serum for future research. The clinicians retain complete autonomy in using MS PATHS data in patient care. A shared governance model ensures transparent data and sample access for research. Results: As of August 5, 2019, MS PATHS enrolment included participants (n = 16,568) with broad ranges of disease subtypes, duration, and severity. Overall, 14,643 (88.4%) participants contributed data at one or more time points. The average patient contributed 15.6 person-months of follow-up (95% CI: 15.5-15.8); overall, 166,158 person-months of follow-up have been accumulated. Those with relapsing-remitting MS demonstrated more demographic heterogeneity than the participants in six randomized phase 3 MS treatment trials. Across sites, a significant variation was observed in the follow-up frequency and the patterns of disease-modifying therapy use. Conclusions: Through digital health technology, it is feasible to collect standardized, quantitative, and interpretable data from each patient in busy MS practices, facilitating the merger of research and patient care. This approach holds promise for data-driven clinical decisions and accelerated systematic learning.

Image quality of flat-panel computed tomography using 2 different acquisition times versus multidetector computed tomography in whole-head temporal bone specimen.

PURPOSE: Imaging of temporal bone and skull base acquire high resolution due to the small anatomic structures with high clinical relevance. The purpose of this study was to compare image quality of the temporal bone in standard 20 s protocol flat-panel computed tomography (FPCT) with the new time- and dose improved 10 s protocol as well as with 128 slice multidetector computed tomography (MDCT). The aim was to evaluate the new time- and dose improved 10 s protocol. METHODS: 10 whole-skull preparations-20 temporal bones-were scanned with either 128 slice MDCT CT (SOMATOM Definition AS + , Siemens, Erlangen) or FPCT (AXIOM-Artis, Siemens, Erlangen) using 10 s or 20 s protocol. RESULTS: We show here that overall FPCT provides significantly better image quality and improved delimitation of clinically relevant structures in the temporal bone compared to 128 slice MDCT. Especially the shorter, dose saving 10 s protocol of the FPCT is still superior to 128 slice MDCT. The 20 s FPCT protocol was only significantly superior in identification of the cochlear apical turn and can thereby be used specifically in clinical cases with pathologies in this area. CONCLUSIONS: The 10 s FPCT protocol yields a significantly better image quality than MDCT in imaging finer structures of the temporal bone.

Dose Optimization of Perfusion-derived Response Assessment in Hepatocellular Carcinoma Treated with Transarterial Chemoembolization: Comparison of Volume Perfusion CT and Iodine Concentration.

RATIONALE AND OBJECTIVES: We assessed the value of iodine concentration (IC) as a perfusion-derived response marker for hepatocellular carcinoma (HCC) treated with transarterial chemoembolization (TACE) in comparison with volume perfusion computed tomography (VPCT) parameters. MATERIALS AND METHODS: Forty-one HCC lesions in 32 patients examined before and after TACE were analyzed retrospectively. VPCT-parameters were calculated and lesion iodine-maps were computed using subtraction of the baseline and the scan 7 seconds after aortic peak enhancement from the corresponding 80 kVp-VPCT data set. Modified RECIST was used as standard response criteria. Comparisons were performed using Student's t test for normal distributed data and Mann-Whitney U test for non-normal distributed data. Additionally, correlation analysis, receiver operating characteristics (ROC) and interreader agreement were assessed. RESULTS: In responding lesions, mean pre-TACE IC and blood flow (BF) were 131.2 mg/100 mL and 96.7 mL/100 mL/min, decreasing to IC 25.6 mg/100 mL (P < 0.001) and BF 28.5 mL/100 mL/min (P < 0.001) post-TACE. In nonresponding lesions, the values remained almost unchanged: pre-TACE: mean BF 79.3 mL/100 mL/min and mean IC 90.4 mg/100 mL; post-TACE: mean BF 71.3 mL/100 mL/min (n.s.) and mean IC 105.4 mg/100 mL (n.s.). Differences in IC-values revealed a high sensitivity/specificity of 96.7%/81.8%. IC and VPCT-parameters showed strong, positive correlations. Mean volume CT dose index for VPCT was 63.4 mGy and 4.9 mGy for iodine maps. CONCLUSION: Thus, IC is a meaningful perfusion marker for local therapy response monitoring in HCC that can be acquired with low radiation dose. This information is important for further therapy response applications using dual and single energy CT.

Positioning a Novel Transcutaneous Bone Conduction Hearing Implant: a Systematic Anatomical and Radiological Study to Standardize the Retrosigmoid Approach, Correlating Navigation-guided, and Landmark-based Surgery.

HYPOTHESIS: Anatomical and radiological evaluation improves safety and accuracy of the retrosigmoid approach for positioning a transcutaneous bone conduction implant and provides anatomical reference data for standardized, landmark-based implantation at this alternative site. BACKGROUND: The primary implantation site for the floating mass transducer of a novel bone conduction hearing implant is the mastoid. However, anatomical limitations or previous mastoid surgery may prevent mastoid implantation. Therefore, the retrosigmoid approach has been introduced as an alternative. METHODS: Mastoid and retrosigmoid implantation sites were radiologically identified and evaluated in preoperative computed tomography scans of anatomical head specimens. Navigation-guided implantation was then performed in the retrosigmoid site (n = 20). The optimal retrosigmoid position was determined in relation to both the asterion and the mastoid notch as surgical landmarks in an anatomical coordinate system. RESULTS: Preoperative radiological analysis revealed spatial limitations in the mastoid in 45% of the specimens. Navigation-guided retrosigmoid implantation was possible without affecting the sigmoid sinus in all the specimens. The optimal implantation site was located 1.9 ±â€Š0.1 cm posterior/1.7 ±â€Š0.1 cm inferior to the asterion and 3.3 ±â€Š0.2 cm posterior/2.1 ±â€Š0.1 cm superior to the mastoid notch.Retrosigmoid skull thickness was 6.6 ±â€Š0.4 mm, measured anatomically, 7.0 ±â€Š0.4 mm, measured radiologically and 6.7 ±â€Š0.5 mm, measured with the navigation software. CONCLUSION: The navigation-guided retrosigmoid approach seemed to be a reliable procedure in all the specimens. Measurements of bone thickness revealed the need for spacers in 95% of the specimens. Reference coordinates of the optimal implantation site are provided and can confirm image-guided surgery or facilitate orientation if a navigation system is not available.

Advanced diffusion-weighted imaging in patients with optic neuritis deficit - value of reduced field of view DWI and readout-segmented DWI.

Objective The objective of this article is to evaluate advanced techniques of diffusion-weighted imaging (DWI) and apparent diffusion coefficient (ADC) measurements of the optic nerve in patients with optic neuritis. Methods In this prospective and institutional review board-approved trial, we examined 15 patients with acute visual loss and clinical signs of optic neuritis including thin-slice multi-shot segmented readout of long variable echo trains (rs-EPI, RESOLVE) DWI and reduced field-of view DWI using a parallel transmit system (rFOV-EPI). Conventional single-shot echo-planar DWI (ss-EPI) of the whole brain was available in 13 patients. Subjective image quality was compared using a four-point scale and objective ADC measurements were performed in comparison with the non-affected side. Results In the intraorbital segment, subjective image quality was significantly higher in rFOV-EPI (score 3.3 ± 0.8) compared with rs-EPI (score 2.1 ± 0.8) and ss-EPI (score 0.9 ± 0.8). Diagnosis was hampered in the canalicular segment ( n = 3) and the intracranial segment ( n = 1) in all applied DWI techniques. ADC measurements of the affected side differed significantly in all DWI sequences ss-EPI (sensitivity 54%, accuracy 77%), rs-EPI (sensitivity 71%, accuracy 86%), and rFOV-EPI (sensitivity 73%, accuracy 87%). Conclusion Optic neuritis in the intraorbital segment can be detected with high sensitivity without the need for contrast application. Using rFOV-EPI improves subjective image quality compared with rs-EPI and ss-EPI. Due to its higher spatial resolution, rFOV-EPI was the preferred technique in our study and can ensure the diagnosis in the intraorbital segment. However, artefacts occur in the canalicular and intracranial segment of the optic nerve, therefore contrast-enhanced T1-weighted images must still be considered as the gold standard.

Prognostic value of perfusion CT in hepatocellular carcinoma treatment with sorafenib: comparison with mRECIST in longitudinal follow-up.

Background Targeted therapies are of increasing clinical importance and classic radiologic therapy response-criteria often fail to detect early therapeutic response or failure. For hepatocellular carcinoma (HCC), this is of major importance as therapeutic options are limited. Purpose To investigate the impact of sorafenib-treatment on intralesional perfusion using perfusion computed tomography (PCT) in HCC and to correlate the observed changes with mRECIST and the course of serum alpha-fetoprotein (AFP) for identification of their prognostic value. Material and Methods PCT was performed before and after two months of sorafenib treatment in 28 consecutive HCC patients and AFP levels were registered. Changes in tumor perfusion parameters blood flow (BF), blood volume (BV), mean transit time (MTT), volume transfer constant (Ktrans), arterial liver perfusion (ALP), and hepatic perfusion index (HPI) were registered in one target lesion. mRECIST measurements were performed at baseline and after two and four months during sorafenib treatment. Results According to mRECIST, after two months of treatment, all patients showed stable disease (SD), whereas after four months, 13 patients (46%) showed SD and 15 patients (54%) showed progressive disease (PD). A significant decrease was found in perfusion parameters BF, BV, Ktrans, ALP, and HPI in patients with SD as well as a significant increase in MTT ( P < 0.05) after two months compared to baseline, while patients with PD showed a significant increase in HPI, BF, and BV. There were no correlations between AFP and mRECIST or perfusion parameters. Conclusion Decreased intralesional BF and HPI after two months of sorafenib treatment predicts disease stabilization after four months, whereas AFP dynamics were of limited value.

Parallel-transmit-accelerated 2D Selective RF Excitation MR of the Temporal Bone: Enhanced Resolution of Labyrinthine and IAC Structures.

RATIONALE AND OBJECTIVES: The purpose of this study was to compare a standard T2 SPACE sequence (standard-SPACE) used in temporal bone imaging at 3 T with a new parallel-transmit-accelerated 2D-selective radio frequency excitation technique for SPACE which was either time-improved or resolution-improved. MATERIALS AND METHODS: Thirty-two consecutive patients were examined in this IRB-approved study using a standard T2 SPACE sequence, and then a time-improved zoomed SPACE sequence (short z-SPACE) with identical resolution but accelerated image acquisition and a resolution-improved zoomed SPACE sequence (high-resolution z-SPACE) with identical acquisition time but higher resolution at a 3-T magnetic resonance imaging system. Signal-to-noise ratio (SNR) was measured within selected regions of interest. Image quality of anatomic temporal bone structures was determined by two independent readers using a four-point visual scale. RESULTS: Significant image quality improvement (p < 0.05) was observed in short z-SPACE and high-resolution z-SPACE, especially in structures of the cochlea and also regarding the delineation of the cranial nerves within the internal auditory canal. SNR measurements showed a lower SNR in the short z-SPACE and high-resolution z-SPACE sequences compared with standard-SPACE. CONCLUSION: At 3 T parallel transmission using the zoomed SPACE sequences improves the delineation of small anatomical structures within the temporal bone significantly. It is especially helpful in depicting cochlear and internal auditory canal anatomy and can therefore improve imaging in patients with temporal bone pathologies.

Comparison of volume perfusion computed tomography and contrast-enhanced ultrasound for assessment of therapeutic effect of transarterial chemoembolization in patients with hepatocellular carcinoma: a preliminary report.

BACKGROUND: Evaluation of transarterial chemoembolization (TACE) by using contrast-enhanced ultrasound (CEUS) and volume perfusion computed tomography (VPCT) as methods that display tumor vascularization. PURPOSE: To assess early results of TACE in patients with hepatocellular carcinoma (HCC) using CEUS and VPCT. MATERIAL AND METHODS: Twenty patients with HCC underwent CEUS and VPCT in the pre- and post-TACE setting (1 day). Hepatic perfusion index (HPI), arterial liver perfusion (ALP), blood flow (BF), and blood volume (BV) were measured with VPCT. Peak intensity (PI), time-to-peak (TTP), and regional blood flow (RBF) were measured with CEUS. Sensitivity, specificity, negative and positive predictive values, and cutoff values for these parameters were calculated. Immediate tumor response after TACE was classified as responder or non-responder. Results were compared with those at follow-up after 2 and 4 months (FU2mo/FU4mo) following modified RECIST. RESULTS: CEUS and VPCT showed comparable immediate post-TACE results in 20/20 cases. Complete response was confirmed in 10/20 patients at FU2mo and in 9/20 at FU4mo. For responders, reduction in HPI, ALP, BV, and BF at day 1 post TACE proved significant (P < 0.001). For non-responders, the course of all VPCT parameters proved non-significant. A cutoff of 40% reduction in HPI and a reduction in ALP of >29.6%, in BV of >41.4%, or in BF of >53.1% was indicative of response according to FU2mo. For responders only, changes in PI (P < 0.001), TTP (P < 0.01), and BF (P < 0.01) proved significant whereas for non-responders, all CEUS parameters proved non-significant. CONCLUSION: CEUS performs equally to VPCT for assessment of early response to TACE in HCC by a lesion-by-lesion assessment and showed prognostic value at mid-term.

Reproducibility of VPCT parameters in the normal pancreas: comparison of two different kinetic calculation models.

RATIONALE AND OBJECTIVES: To assess the reproducibility of volume computed tomographic perfusion (VPCT) measurements in normal pancreatic tissue using two different kinetic perfusion calculation models at three different time points. MATERIALS AND METHODS: Institutional ethical board approval was obtained for retrospective analysis of pancreas perfusion data sets generated by our prospective study for liver response monitoring to local therapy in patients experiencing unresectable hepatocellular carcinoma, which was approved by the institutional review board. VPCT of the entire pancreas was performed in 41 patients (mean age, 64.8 years) using 26 consecutive volume measurements and intravenous injection of 50 mL of iodinated contrast at a flow rate of 5 mL/s. Blood volume(BV) and blood flow (BF) were calculated using two mathematical methods: maximum slope + Patlak analysis versus deconvolution method. Pancreas perfusion was calculated using two volume of interests. Median interval between the first and the second VPCT was 2 days and between the second and the third VPCT 82 days. Variability was assessed with within-patient coefficients of variation (CVs) and Bland-Altman analyses. Interobserver agreement for all perfusion parameters was calculated using intraclass correlation coefficients (ICCs). RESULTS: BF and BV values varied widely by method of analysis as did within-patient CVs for BF and BV at the second versus the first VPCT by 22.4%/50.4% (method 1) and 24.6%/24.0% (method 2) measured in the pancreatic head and 18.4%/62.6% (method 1) and 23.8%/28.1% (method 2) measured in the pancreatic corpus and at the third versus the first VPCT by 21.7%/61.8% (method 1) and 25.7%/34.5% (method 2) measured also in the pancreatic head and 19.1%/66.1% (method 1) and 22.0%/31.8% (method 2) measured in the pancreatic corpus, respectively. Interobserver agreement measured with ICC shows fair-to-good reproducibility. CONCLUSIONS: VPCT performed with the presented examinational protocol is reproducible and can be used for monitoring purposes. Best reproducibility was obtained with both methods for BF and with method 2 also for BV data for both follow-up studies.

Feasibility and evaluation of dual-source transmit 3D imaging of the orbits: Comparison to high-resolution conventional MRI at 3T.

PURPOSE: To prospectively compare the image quality and diagnostic performance of orbital MR images obtained by using a dual-source parallel transmission (pTX) 3D sequence (Sampling Perfection with Application optimized Contrasts using different flip angle Evolution, SPACE) with the image quality of conventional high-resolution standard protocol for clinical use in patients at 3T. MATERIALS AND METHODS: After obtaining institutional review board approval and patient consent, 32 patients with clinical indication for orbital MRI were examined using a high-resolution conventional sequences and 3D pTX SPACE sequences. Quantitative measurements, image quality of the healthy orbit, incidence of artifacts, and the subjective diagnostic performance to establish diagnosis was rated. Statistical significance was calculated by using a Student's t-test and nonparametric Wilcoxon signed rank test. RESULTS: Length measurements were comparable in the two techniques, 3D pTX SPACE resulted in significant faster image acquisition with higher spatial resolution and less motion artifacts as well as better delineation of the optic nerve sheath. However, estimated contrast-to-noise and signal-to-noise and overall image quality as well as subjective scores of the conventional TSE imaging were rated significantly higher. The conventional MR sequences were the preferred techniques by the readers. CONCLUSION: This study demonstrates the feasibility of 3D pTX SPACE of the orbit resulting in a rapid acquisition of isotropic high-resolution images. Although no pathology was missed in 3D pTX SPACE, conventional MRI techniques showed the higher diagnostic confidence in our study, presumably due to the higher signal-to-noise and contrast-to-noise ratios. We observed high-resolution TSE imaging to be the preferred technique, 3D pTX SPACE cannot replace conventional MRI so far.

Modern multimodality diagnosis of portal vein infiltration in hepatocellular carcinoma and expected changes during current therapies.

Diagnosis of malignant portal vein infiltration and especially differentiation from bland thrombosis is challenging for most imaging techniques. The use of contrast-enhanced real-time modern imaging modalities like contrast-enhanced ultrasound (CEUS), volume perfusion CT (VPCT), or dynamic contrast-enhanced MRI (DCE-MRI) with dedicated postprocessing tools provides additional support in difficult cases and is therefore recommended.The purpose of this review is to present a practical overview of strengths and limitations of modern imaging techniques in the diagnosis of malignant infiltration of the portal vein by hepatocellular carcinoma and to describe subsequent changes during therapy.