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OBJECTIVES: To evaluate the diagnostic performance of simplified post-processing approaches for quantitative wrist 4D-CT in the assessment of scapholunate instability (SLI). METHODS: A prospective monocentric case-control study included 60 patients with suspected post-traumatic scapholunate ligament (SLL) tears and persistent pain. Of these, 40 patients exhibited SLL tears, subdivided into two groups of 20 each: one group with completely torn ligaments and the other with partially torn ligaments. The remaining 20 patients, whose SLLs were intact, served as controls. 4D-CT and CT arthrography were performed, and post-processed by two readers using three approaches: the standard method with full data assessment and dedicated software, partial data assessment with post-processing software (bone locking), and partial data assessment without post-processing software (no bone locking). The scapholunate gap (SLG) parameter was measured in millimeters to evaluate scapholunate diastasis during radioulnar deviation (RUD). The scapholunate ligament status on CT arthrography was considered the gold standard. RESULTS: The SLG-derived parameters (range, mean, and maximal values) were significantly increased in patients with both intact and torn scapholunate ligaments across all post-processing approaches (P values ranging from 0.001 to 0.004). SLG range was the best parameter for diagnosing SLL tears, with ROC AUC values ranging from 0.7 to 0.88 across the three post-processing methods. The interobserver reproducibility was better with the alternative approaches (ICC values 0.93-0.96) compared to the standard approach (ICC values 0.65-0.72). Additionally, post-processing time was shorter with the alternative approaches, especially when specific software was not used (reduced from 10 to three minutes). CONCLUSION: Simpler approaches to wrist 4D-CT data analysis yielded acceptable diagnostic performances and improved interobserver reproducibility compared to the standard approach.

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BACKGROUND AND PURPOSE: Parathyroid carcinoma is the rarest endocrine neoplasm with very few published data discussing its imaging appearance with primary focus on ultrasound imaging features. We present our 23 years institutional experience to highlight multimodality imaging evaluation at presentation and at recurrence. MATERIAL AND METHODS: Retrospective chart review of clinical and pathological diagnosis of parathyroid carcinoma patients presented for initial or recurrent disease management at M.D. Anderson Cancer Center between the period of January 2000 and February 2023 was performed. Imaging findings on US, CT, PET/CT, and technetium-99m sestamibi were analyzed for initial and local recurrent parathyroid carcinoma. We further assess patterns of distant recurrence and its location. RESULTS: Twenty three patients with pathological and clinical diagnosis of initial (14 patients) or recurrent parathyroid carcinoma (14 patients) were included in this study. US findings of parathyroid carcinoma were larger lesions, increased/irregular vascularity, and non-circumscribed margins. Multiphasic CT findings of parathyroid carcinoma included an arterially enhancing lesion that is hypoenhancing relative to the thyroid and demonstrates no washout on delayed imaging. Highly suggestive findings for recurrent disease included a hypoechoic solid nodule (91.67%) with increased vascularity on ultrasound (81.8%) with corresponding enhancement on CT. CONCLUSION: Parathyroid carcinoma is a rare malignancy often diagnosed after surgical resection. We provided CT and US imaging features that are helpful in suggesting the diagnosis of parathyroid carcinoma and detection of early local recurrence.

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Deviceless four-dimensional (4D) computed tomography (CT) allows the acquisition of respiratory signals from six features without requiring an external device for cine CT processing. This method has been recently introduced in radiation treatment planning of lung tumors. To validate deviceless 4D CT, it must be compared with conventional 4D CT, which requires an external monitoring device. We compared the two methods using a multicell 4D phantom that simulates patient's movement during respiration regarding the target volume (TV), target position (TP), and internal TV for lung tumor radiation therapy. We retrospectively obtained images of 10 patients who underwent radiation treatment planning of lung tumors and compared the two methods, as in the phantom study. For the phantom study, the mean TV, root mean square errors of the TP, and mean internal TV differences between the two methods ranged from -4.5% to 1.2%, 0.7 to 2.6 mm, and -1.1% to 3.4%, respectively. The corresponding results of the clinical study ranged from -1.5% to 14.9%, 0.1 to 5.9 mm, and -9.7% to 10.1%, respectively. The results of deviceless 4D CT for the clinical study were consistent with those of conventional 4D CT, except for target movements with high excursions. Therefore, deviceless 4D CT can be an alternative to conventional 4D CT for radiation treatment planning of lung tumors.

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Contrast enhancement at the margins/rim of embolization areas in hepatocellular-carcinoma (HCC) lesions treated with transarterial chemoembolization (TACE) might be an early prognostic indicator for HCC recurrence. The aim of this study was to evaluate the predictive value of rim perfusion for TACE recurrence as determined by perfusion CT (PCT). A total of 52 patients (65.6 ± 9.3 years) underwent PCT directly before, immediately after (within 48 h) and at follow-up (95.3 ± 12.5 days) after TACE. Arterial-liver perfusion (ALP), portal-venous perfusion (PVP) and hepatic-perfusion index (HPI) were evaluated in normal liver parenchyma, and on the embolization rim as well as the tumor bed. A total of 42 lesions were successfully treated, and PCT measurements showed no residually vascularized tumor areas. Embolization was not entirely successful in 10 patients with remaining arterialized focal nodular areas (ALP 34.7 ± 10.1 vs. 4.4 ± 5.3 mL/100 mL/min, p < 0.0001). Perfusion values at the TACE rim were lower in responders compared to normal adjacent liver parenchyma and edges of incompletely embolized tumors (ALP liver 16.3 ± 10.1 mL/100 mL/min, rim responder 8.8 ± 8.7 mL/100 mL/min, rim non-responder 23.4 ± 8.6 mL/100 mL/min, p = 0.005). At follow-up, local tumor relapse was observed in 17/42, and 15/42 showed no recurrence (ALP 39.1 ± 10.1 mL/100 mL/min vs. 10.0 ± 7.4 mL/100 mL/min, p = 0.0008); four patients had de novo disseminated disease and six patients were lost in follow-up. Rim perfusion was lower compared to adjacent recurring HCC and not different between groups. HCC lesions showed no rim perfusion after TACE, neither immediately after nor at follow-up at three months, both for mid-term responders and mid-term relapsing HCCs, indicating that rim enhancement is not a sign of reactive hyperemia and not predictive of early HCC recurrence.

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PURPOSE: The accuracy of target delineation for node-positive thoracic tumors is dependent on both four-dimensional computed tomography (4D-CT) and contrast-enhanced three-dimensional (3D)-CT images; these scans enable the motion visualization of tumors and delineate the nodal areas. Combining the two techniques would be more effective; however, currently, there is no standard protocol for the contrast media injection parameters for contrast-enhanced 4D-CT (CE-4D-CT) scans because of its long scan durations and complexity. Thus, we aimed to perform quantitative and qualitative assessments of the image quality of single contrast-enhanced 4D-CT scans to simplify this process and improve the accuracy of target delineation in order to replace the standard clinical modality involved in administering radiotherapy for thoracic tumors. METHODS: Ninety consecutive patients with thoracic tumors were randomly and parallelly assigned to one of nine subgroups subjected to CE-4D-CT scans with the administration of contrast agent volume equal to the patient's weight but different flow rate and scan delay time (protocol A1: flow rate of 2.0 ml/s, delay time of 15 s; A2: 2.0 ml/s, 20 s; A3: 2.0 ml/s, 25 s; B1: 2.5 ml/s, 15 s; B2: 2.5 ml/s, 20 s; B3: 2.5 ml/s, 25 s; C1: 3.0 ml/s, 15 s; C2: 3.0 ml/s, 20 s; C3: 3.0 ml/s, 25 s). The Hounsfield unit (HU) values of the thoracic aorta, pulmonary artery stem, pulmonary veins, carotid artery, and jugular vein were acquired for each protocol. Both quantitative and qualitative image analysis and delineation acceptability were assessed. RESULTS: The results revealed significant differences among the nine protocols. Enhancement of the vascular structures in mediastinal and perihilar regions was more effective with protocol A1 or A2; however, when interested in the region of superior mediastinum and supraclavicular fossa, protocol C2 or C3 is recommended. CONCLUSION: Qualitatively acceptable enhancement on contrast-enhanced 4D-CT images of thoracic tumors can be obtained by varying the flow rate and delay time when minimal contrast agent is used.

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OBJECTIVES: To investigate the incremental value of Sestamibi SPECT combined with a non-enhanced and contrast-enhanced CT, using SPECT/CT, for the preoperative localisation of small parathyroid adenomas (PTA). METHODS: Retrospectively, 147 patients surgically cured from primary hyperparathyroidism, as verified by biochemistry 6 months postoperatively, were included. All patients had preoperatively undergone a dual time 99mTechnetium-Sestamibi SPECT (S) with multiphase CT including native (N), arterial (A) and venous (V) phases. Independently, two radiologists blinded from both the surgical and the preoperative imaging reports, sequentially performed PTA localisation starting with either [A] or [V], thereafter [A + N] or [V + N] and finally with the complete [A + N + S] or [V + N + S]. PTA localisation was reported for each image-set. The readers results were combined and the diagnostic performance for each image set was determined. Sensitivity was also calculated for the different quartiles of PTA weight distribution. RESULTS: The median adenoma weight was 315 mg. No statistically significant differences in diagnostic performance between arterial and venous based image sets were found. The net effect of adding [N] was to increase specificity. Sestamibi SPECT significantly increased the overall diagnostic accuracy for arterial- and venous-based image sets, p = 0.0008 and p = 0.001, respectively. [A + N + S] was found to have the highest diagnostic performance with 86.5% sensitivity and 94.9% overall accuracy. [A + N + S] was particularly advantageous for locating PTA in the lower weight quartiles. CONCLUSIONS: Native CT-phase and dual time point Sestamibi SPECT increase specificity and sensitivity, respectively. These, in combination with a single contrast-enhanced CT-phase is the most optimal examination protocol for preoperative localisation of PTA using SPECT/CT.

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We report the case of a 64-year-old female diagnosed with severe pulmonary hypertension due to the unilateral absence of a pulmonary artery. The four-dimensional computed tomography scan is a useful modality for revealing detailed anatomical findings for differential diagnoses and surgical decision-making. The patient had severe pulmonary hypertension with a mean pulmonary artery pressure (PAP) of 74 mmHg and was treated with triple upfront combination therapy, leading to significant improvement in pulmonary haemodynamics (to 27 mmHg in mean PAP) and functional capacity (WHO functional class, from III to II; 6-min walk distance, from 211 to 276 m).

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OBJECTIVE: To investigate differences between reconstruction algorithms in quantitative perfusion values and time-attenuation curves in computed tomography perfusion (CTP) examinations of the upper abdomen. METHODS: Twenty-six CTP examinations were reconstructed with filtered back projection and an iterative reconstruction algorithm, advanced modeled iterative reconstruction (ADMIRE), with different levels of noise-reduction strength. Using the maximum-slope model, quantitative measurements were obtained: blood flow (mL/min/100 mL), blood volume (mL/100 mL), time to peak (s), arterial liver perfusion (mL/100 mL/min), portal venous liver perfusion (mL/100 mL/min), hepatic perfusion index (%), temporal maximum intensity projection (Hounsfield units (HU)) and temporal average HU. Time-attenuation curves for seven sites (left liver lobe, right liver lobe, hepatocellular carcinoma, spleen, gastric wall, pancreas, portal vein) were obtained. Mixed-model analysis was used for statistical evaluation. Image noise and the signal:noise ratio (SNR) were compared between four reconstructions, and statistical analysis of these reconstructions was made with a related-samples Friedman's two-way analysis of variance by ranks test. RESULTS: There were no significant differences for quantitative measurements between the four reconstructions for all tissues. There were no significant differences between the AUC values of the time-attenuation curves between the four reconstructions for all tissues, including three automatic measurements (portal vein, aorta, spleen). There was a significant difference in image noise and SNR between the four reconstructions. CONCLUSIONS: ADMIRE did not affect the quantitative measurements or time-attenuation curves of tissues in the upper abdomen. The image noise was lower, and the SNR higher, for iterative reconstructions with higher noise-reduction strengths.

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INTRODUCTION: Recurrent hyperparathyroidism is difficult to manage due to the difficulty in finding the missing adenoma. Herein we present a case of recurrent hyperparathyroidism from ectopic adenomas which basic investigations failed to locate but were finally localized by a 4DCT following selective venous sampling (SVS) of parathyroid hormone (PTH). PRESENTATION OF CASE: A young female presented with recurrent hyperparathyroidism. She had severe primary hyperparathyroidism and temporary normocalcemia after first parathyroidectomy. Her hypercalcemia recurred and required second operation. However, the second operation was unsuccessful due to the pre-operation ultrasound, computed tomography (CT) neck, and sestamibi failed to identify the culprit parathyroid adenoma. After the second operation, positron emission tomography (PET), CT neck and sestamibi failed to identify the tumor but a sequence of SVS PTH and four-dimensional computed tomography (4DCT) successfully identified several ectopic adenomas. DISCUSSION: Ectopic parathyroid tissue is the most common cause of recurrent hyperparathyroidism but precisely locating these ectopic glands is often challenging. Despite modern modalities such as PET scans, the success rate is not impressive. SVS PTH is a good method to regionalize the ectopic source of PTH. With the more specified area, fine-tuning imaging with a 4DCT can identify the specific location of the ectopic parathyroid tissue. CONCLUSION: A sequence of SVS PTH followed by 4DCT could identify the exact location of ectopic parathyroid adenomas in a patient when conventional non-invasive imaging studies failed.

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The purpose of this work was to determine the actual dose received by normal tissues during four-dimensional radiation therapy (4DRT) composed of ten phases of four-dimensional computer tomography (4DCT) images. The analysis was performed by tracking the hepatocellular carcinoma SBRT. Data were acquired from the tracking of each phase with the beam aperture for 28 hepatocellular carcinoma patients, and the data were used to generate a cumulative plan, which was compared to a three-dimensional (3D) plan formed from a merged target volume based on 4DCT images in a radiation treatment planning system (TPS). The change in normal tissue dose was evaluated in the plan using the parameters V5, V10, V15, V20, V25, V30, V35, and V40 (volumes receiving 5, 10, 15, 20, 25, 30, 35, and 40 Gy, respectively) in the dose-volume histogram for the liver; the mean dose was analyzed for the following tissues: liver, left kidney, and right kidney. The maximum dose was analyzed for the following tissues: bowel, duodenum, esophagus, stomach, and heart. There was a significant difference in the dose between the 4D planning target volume (PTV) (average 115.71 cm3 ) and ITV (169.86 cm3 ). The planning objective was for 95% of the volume of the PTV to be covered by the prescription dose, but the mean dose for the liver, left kidney and right kidney had an average decrease of 23.13%, 49.51%, and 54.38%, respectively. The maximum dose for the bowel, duodenum, esophagus, stomach, and heart had an average decrease of 16.77%, 28.07%, 24.28%, 4.89%, and 4.45%, respectively. Compared to 3D RT, the radiation volume for the liver V5, V10, V15, V20, V25, V30, V35, and V40 using the 4D plans had a significant decrease (P ï¹¤ 0.05). The 4D method creates plans that permit sparing of the normal tissues more than the commonly used ITV method, which delivers the same dosimetric effects to the target.

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PURPOSE: To investigate the impact of intra- and inter-fractional esophageal motion on dosimetry and observed toxicity in a phase I dose escalation study of accelerated radiotherapy with concurrent chemotherapy for locally advanced lung cancer. METHODS AND MATERIALS: Patients underwent computed tomography imaging for radiotherapy treatment planning (CT1 and 4DCT1) and at 2 weeks (CT2 and 4DCT2) and 5 weeks (CT3 and 4DCT3) after initiating treatment. Each computed tomography scan consisted of 10-phase 4DCTs in addition to a static free-breathing or breath-hold computed tomography. The esophagus was independently contoured on all computed tomographies and 4DCTs. Both CT2 and CT3 were rigidly registered with CT1 and doses were recalculated using the original intensity-modulated radiation therapy plan based on CT1 to assess the impact of interfractional motion on esophageal dosimetry. Similarly, 4DCT1 data sets were rigidly registered with CT1 to assess the impact of intrafractional motion. The motion was characterized based on the statistical analysis of slice-by-slice center shifts (after registration) for the upper, middle, and lower esophageal regions, respectively. For the dosimetric analysis, the following quantities were calculated and assessed for correlation with toxicity grade: the percent volumes of esophagus that received at least 20 Gy (V20) and 60 Gy (V60), maximum esophageal dose, equivalent uniform dose, and normal tissue complication probability. RESULTS: The interfractional center shifts were 4.4 ± 1.7 mm, 5.5 ± 2.0 mm and 4.9 ± 2.1 mm for the upper, middle, and lower esophageal regions, respectively, while the intrafractional center shifts were 0.6 ± 0.4 mm, 0.7 ± 0.7 mm, and 0.9 ± 0.7 mm, respectively. The mean V60 (and corresponding normal tissue complication probability) values estimated from the interfractional motion analysis were 7.8% (10%), 4.6% (7.5%), 7.5% (8.6%), and 31% (26%) for grade 0, grade 1, grade 2, and grade 3 toxicities, respectively. CONCLUSIONS: Interfractional esophageal motion is significantly larger than intrafractional motion. The mean values of V60 and corresponding normal tissue complication probability, incorporating interfractional esophageal motion, correlated positively with esophageal toxicity grade.

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PURPOSE: The accuracy and precision of computed tomography (CT) pulmonary ventilation imaging with conventional CT scanners are limited by breathing variations. We propose a method to correct for the effect of breathing variations in CT ventilation imaging based on external respiratory signals acquired throughout a scan. METHODS: The proposed method is based on: (a) calculating voxel-by-voxel abdominal surface motion ranges using four-dimensional (4D) CT image datasets spatiotemporally correlated with external respiratory monitor data, and (b) applying the correction factor, which is defined as the ratio of the overall mean of the abdominal surface motion range in the lungs to that of each voxel, to the CT ventilation value. The performance of the proposed method was investigated by comparing voxel-wise correlations of the uncorrected and corrected CT ventilation images with single-photon emission CT (SPECT) ventilation images as a ground truth for nine patients. CT ventilation images were calculated by deformable image registration of the 4D-CT image datasets, followed by calculation of regional volume changes. A Steiger's Z-test was used to determine the statistical significance of the difference between the correlations for the uncorrected and corrected CT ventilation images. RESULTS: The proposed correction method resulted in significant increases (P < 0.05) in the correlation between CT and SPECT ventilation in three patients, trends toward significant increase (P: 0.13-0.18) in two patients, no significant differences in three patients, and a significantly decreased correlation in one patient. The average standard deviation of the abdominal surface motion range in three patients showing significant increases was 0.27 (range 0.10-0.37), which was greater than 0.17 (range 0.07-0.38) in the other six patients. CONCLUSIONS: The proposed method to correct for the effect of breathing variations could be readily implemented and has the potential to improve the accuracy of CT ventilation imaging as demonstrated in a nine-patient study.

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INTRODUCTION: To assess laryngeal motion in early glottic cancer in order to determine safe margins for partial larynx volumetric modulated arc therapy (PL-VMAT), and to quantify dosimetric advantages of PL-VMAT. METHODS: This prospective study included T1-2N0 glottic cancers treated with whole larynx VMAT (WL-VMAT). Pre- and mid-treatment 4D-computed tomography (4D-CT) and dynamic magnetic resonance imaging (MRI) allowed for assessment of larynx swallowing and respiratory motion. For 10 patients with lateralized lesions, PL-VMAT plans were calculated using margins derived from 4D-CT analysis. RESULTS: Twenty patients were accrued from 2014 to 2016. Mean amplitude of larynx swallowing excursion was 23 mm and 6 mm in the superior and anterior directions, respectively. Mean respiratory motion reached 4 mm and 2 mm in superior-inferior and antero-posterior directions, respectively. Pre-treatment 4D-CT analysis identified one patient with planning CT acquired during swallowing. Mid-treatment 4D-CT revealed larynx shift relative to vertebrae in 30% of cases. PL-VMAT allowed for significant reduction of mean doses to ipsilateral carotid, contralateral carotid, thyroid gland, contralateral arytenoid and larynx. Using 8 mm internal margin for PL-VMAT, swallowing resulted in clinical target volume excursion beyond 95% isodose line during ≤1.5% of total treatment time in all patients. CONCLUSION: Although swallowing motion is rare, rapid and easily suppressed by patients, there is a risk of systematic miss-targeting if planning CT is acquired during swallowing. Larynx position shift relative to vertebrae occurs in 1/3 of patients over the course of radiotherapy. With soft-tissue image guidance and margins accounting for respiratory motion, PL-VMAT allows safe reduction of dose to organs at risk.

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PURPOSE: Magnetic resonance imaging-guided radiation therapy has entered clinical practice at several major treatment centers. Treatment of early-stage non-small cell lung cancer with stereotactic body radiation therapy is one potential application of this modality, as some form of respiratory motion management is important to address. We hypothesize that magnetic resonance imaging-guided tri-cobalt-60 radiation therapy can be used to generate clinically acceptable stereotactic body radiation therapy treatment plans. Here, we report on a dosimetric comparison between magnetic resonance imaging-guided radiation therapy plans and internal target volume-based plans utilizing volumetric-modulated arc therapy. MATERIALS AND METHODS: Ten patients with early-stage non-small cell lung cancer who underwent radiation therapy planning and treatment were studied. Following 4-dimensional computed tomography, patient images were used to generate clinically deliverable plans. For volumetric-modulated arc therapy plans, the planning tumor volume was defined as an internal target volume + 0.5 cm. For magnetic resonance imaging-guided plans, a single mid-inspiratory cycle was used to define a gross tumor volume, then expanded 0.3 cm to the planning tumor volume. Treatment plan parameters were compared. RESULTS: Planning tumor volumes trended larger for volumetric-modulated arc therapy-based plans, with a mean planning tumor volume of 47.4 mL versus 24.8 mL for magnetic resonance imaging-guided plans ( P = .08). Clinically acceptable plans were achievable via both methods, with bilateral lung V20, 3.9% versus 4.8% ( P = .62). The volume of chest wall receiving greater than 30 Gy was also similar, 22.1 versus 19.8 mL ( P = .78), as were all other parameters commonly used for lung stereotactic body radiation therapy. The ratio of the 50% isodose volume to planning tumor volume was lower in volumetric-modulated arc therapy plans, 4.19 versus 10.0 ( P < .001). Heterogeneity index was comparable between plans, 1.25 versus 1.25 ( P = .98). CONCLUSION: Magnetic resonance imaging-guided tri-cobalt-60 radiation therapy is capable of delivering lung high-quality stereotactic body radiation therapy plans that are clinically acceptable as compared to volumetric-modulated arc therapy-based plans. Real-time magnetic resonance imaging provides the unique capacity to directly observe tumor motion during treatment for purposes of motion management.

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RATIONALE AND OBJECTIVES: To evaluate the role of perfusion CT for monitoring inflammatory activity in patients with aortitis and chronic periaortitis undergoing immunosuppressive therapy. MATERIALS AND METHODS: Seventeen symptomatic patients (median age 68.5 years) who underwent perfusion-based computed tomography (CT) monitoring after diagnostic contrast-enhanced CT were retrospectively included in this study. Blood flow (BF), blood volume (BV), volume transfer constant (k-trans), time to peak, and mean transit time were determined by setting circular regions of interest in prominently thickened parts of the vessel wall or perfused surrounding tissue at sites where the perfusion CT color maps showed a maximum BF value. Differences in CT perfusion and, morphological parameters, C-reactive protein (CRP), and erythrocyte sedimentation rate (ESR) were tested for significance during therapy. RESULTS: In all patients BF and BV dropped at second perfusion CT (P < 0.05). In aortitis patients, CRP dropped from 3.86 ± 5.31 mg/dL to 0.9 ± 1.37 mg/dL and in periaortitis patients from 1.78 ± 2.25 mg/dL to 0.79 ± 1.55 mg/dL, whereas ESR dropped from 45.71 ± 37.59 seconds to 8.57 ± 3.1 seconds and 36.78 ± 34.67 seconds to 17.22 ± 21.82 seconds in aortitis and in periaortitis, respectively. CONCLUSIONS: The course of perfusion CT parameters in aortitis and chronic periaortitis undergoing immunosuppressive therapy dropped at different extent after therapy.

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Stereotactic radiosurgery has long been recognized as the optimal form of management for high-grade arteriovenous malformations not amenable to surgical resection. Radiosurgical plans have generally relied upon the integration of stereotactic magnetic resonance angiography (MRA), standard contrast-enhanced magnetic resonance imaging (MRI), or computed tomography angiography (CTA) with biplane digital subtraction angiography (DSA). Current options are disadvantageous in that catheter-based biplane DSA is an invasive test associated with a small risk of complications and perhaps more importantly, the two-dimensional nature of DSA is an inherent limitation in creating radiosurgical contours. The necessity of multiple scans to create DSA contours for radiosurgical planning puts patients at increased risk. Furthermore, the inability to import two-dimensional plans into some radiosurgery programs, such as Cyberknife TPS, limits treatment options for patients. Defining the nidus itself is sometimes difficult in any of the traditional modalities as all draining veins and feeding arteries are included in the images. This sometimes necessitates targeting a larger volume, than strictly necessary, with stereotactic radiosurgery for treatment of the AVM. In this case report, we show the ability to use a less-invasive and three-dimensional form of angiography based on time-lapsed CTA (4D-CTA) rather than traditional DSA for radiosurgical planning. 4D-CTA may allow generation of a series of images, which can show the flow of contrast through the AVM. A review of these series may allow the surgeon to pick and use a volume set that best outlines the nidus with least interference from feeding arteries or draining veins. In addition, 4D-CTA scans can be uploaded into radiosurgery programs and allow three-dimensional targeting. This is the first reported case demonstrating the use of a 4D CTA and an MRI to delineate the AVM nidus for Gamma Knife radiosurgery, with complete obliteration of the nidus over time and subsequent management of associated radiation necrosis with bevacizumab.

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OBJECTIVE: Recent studies have shown the efficacy of mechanical thrombectomy in acute ischemic stroke. We sought to identify prognostic parameters for clinical and radiological outcome after mechanical thrombectomy. METHODS: In 34 patients (age 72 ± 13 years, 64.7% women) with acute occlusion of the distal ICA and/or M1 segment who were treated with mechanical thrombectomy, the Spearman correlation was performed to assess potential prognostic outcome parameters (age, NIHSS, ASPECT, thrombus length (TL), clot burden score (CBS), relative filling time delay (rFTD), time to recanalization (TTR) and TICI score). The modified Rankin scale (mRS) and the Alberta Stroke Program Early CT (ASPECT) score were used for clinical and radiological outcome, respectively. Receiver operating characteristic (ROC) analysis was performed to assess parameters predicting favorable clinical (ΔmRS ≤ 2) and radiological outcome (ΔASPECT ≤ 2). RESULTS: Variables associated with favorable clinical outcome included NIHSS, TL, TTR and TICI score (p ≤ 0.01) with NIHSS ≤ 15 (p = 0.001, area under the curve (AUC) 0.87), TL ≤ 2 cm (p = 0.017, AUC 0.75), TTR ≤ 231 min (p = 0.001 AUC 0.88) and TICI ≥ 2b (p = 0.050, AUC 0.70). Shorter TTR and higher TICI scores were associated with favorable radiological outcome (p < 0.001) with TTR ≤ 224 min (p = 0.023, AUC 0.77) and TICI ≥ 2b (p = 0.000, AUC 0.86). CONCLUSION: Fast and complete recanalization is essential to achieve a favorable radiological and functional outcome after mechanical thrombectomy in acute ischemic stroke. Age, CBS and collateral supply play a subordinate role.

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PURPOSE: New imaging protocols for radiotherapy in localized gastric lymphoma were evaluated to optimize planning target volume (PTV) margin and determine intra-/interfractional variation of the stomach. METHODS: Imaging of 6 patients was explored prospectively. Intensity-modulated radiotherapy (IMRT) planning was based on 4D/3D imaging of computed tomography (CT) and positron-emission tomography (PET)-CT. Static and motion gross tumor volume (sGTV and mGTV, respectively) were distinguished by defining GTV (empty stomach), clinical target volume (CTV = GTV + 5 mm margin), PTV (GTV + 10/15/20/25 mm margins) plus paraaortic lymph nodes and proximal duodenum. Overlap of 4D-Listmode-PET-based mCTV with 3D-CT-based PTV (increasing margins) and V95/D95 of mCTV were evaluated. Gastric shifts were determined using online cone-beam CT. Dose contribution to organs at risk was assessed. RESULTS: The 4D data demonstrate considerable intra-/interfractional variation of the stomach, especially along the vertical axis. Conventional 3D-CT planning utilizing advancing PTV margins of 10/15/20/25 mm resulted in rising dose coverage of mCTV (4D-Listmode-PET-Summation-CT) and rising D95 and V95 of mCTV. A PTV margin of 15 mm was adequate in 3 of 6 patients, a PTV margin of 20 mm was adequate in 4 of 6 patients, and a PTV margin of 25 mm was adequate in 5 of 6 patients. CONCLUSION: IMRT planning based on 4D-PET-CT/4D-CT together with online cone-beam CT is advisable to individualize the PTV margin and optimize target coverage in gastric lymphoma.

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PURPOSE: It has been reported that the extent of intravascular thrombi and the quality of collateral filling in computed tomography (CT) angiography are predictive for the clinical outcome in patients with acute stroke. We hypothesized that multi-phase four-dimensional CTA (4D-CTA) allows better assessment of clot burden and collateral flow compared with arterial single-phase CTA (CTA). METHODS: In 49 patients (33 female; age: 77 ± 12 years) with acute anterior circulation stroke, CTA and 4D-CTA reconstructed from dynamic perfusion CT data were analyzed for absolute thrombus length (TL), clot burden score (CBS), and collateral score (CS). The length of the filling defect was also defined on thin-slice nonenhanced CT as corresponding hyperdense middle cerebral artery sign (HMCAS) when present. RESULTS: There was good correlation (r = 0.62, p < 0.01) between the length of HMCAS (1.29 ± 0.62 cm) and TL in 4D-CTA (1.22 ± 0.51 cm). 4D-CTA and CTA significantly varied (p < 0.01) in TL (1.42 ± 0.73 cm (CTA) versus 1.11 ± 0.62 cm (4D-CTA)), CBS (median: 5, interquartile range: 4-7 (CTA) versus median: 6, interquartile range: 5-8 (4D-CTA); p < 0.001), and CS (median: 2, interquartile range: 1-2 (CTA) versus median: 3, interquartile range: 2-3 (4D-CTA); p < 0.001). Accordingly, CTA significantly overrated clot burden and underestimated collateral flow. CONCLUSIONS: 4D-CTA more closely defines clot burden and collateral supply in anterior circulation stroke than CTA, implicating an additional diagnostic benefit.

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