Are the washout values currently accepted for lesion characterization in dedicated adrenal CT adequate for diagnosis?

PURPOSEWe aimed to investigate the accuracy of density characteristics and washout values of lesions detected on computed tomography (CT) at the cutoff values obtained from the literature by taking the pathological results of adrenalectomy specimens as reference and to determine the cutoff values of parameters evaluated on CT for the differentiation of adenoma and nonadenoma lesions in the study group.METHODSHospital records and standard CT imaging data (noncontrast early phase [65 s] and late phase [15 min] ) of 84 patients with 87 lesions who underwent adrenalectomy between January 2012 and December 2018 were retrospectively reevaluated by two radiologists in consensus. The patients were categorized as having adenoma and nonadenoma lesions according to the pathology results. The sensitivity, specificity and diagnostic accuracy of CT parameters (density values and washout percentages) were evaluated. Differences in the CT parameters (size, noncontrast and early-late enhancement density and absolute and relative washout values) were investigated. The optimal cutoff values of CT parameters were determined by ROC analysis.RESULTSNoncontrast CT had a specificity of 87.75% and 95.9%, sensitivity of 60% and 48.6%, diagnostic accuracy of 77.7% and 89.47% for adenomas, at the cutoff values of ≤10 HU and ≤0 HU, respectively. For absolute washout value ≥ 60%, the sensitivity, specificity and accuracy were 64.7%, 52.38% and 56.75%, respectively; while these rates were 76.47%, 56.52% and 62.16%, respectively, for relative washout value ≥40%. Adenomas and nonadenomas showed significant difference in terms of size (p < 0.0001), unenhanced attenuation (p < 0.0001), relative washout (p = 0.020) and delay enhancement (p < 0.001). But there were no differences in terms of absolute washout (p = 0.230) and early enhancement (p = 0.264). The cutoff values for the differentiation of adenomas and nonadenomas were as follows: size ≤44 mm, noncontrast density <20 HU, early-phase density ≥45 HU, delayed-phase density ≤44 HU, absolute washout 74.83% and relative washout 57.76%.CONCLUSIONThe current washout criteria used in the differentiation of adenoma and nonadenoma lesions in dynamic CT imaging can give false negative and positive results. According to the existing criteria, the most reliable parameter in adenoma–nonadenoma differentiation is ≤ 0 HU noncontrast CT density value.

According to the autopsy studies, adrenal masses are among the most common tumors detected in humans (1). In autopsy series, this prevalence has been reported as 1% to 9.8% (1). With the advances in imaging techniques and their increasing use, there has also been a recent increase in radiologically reported adrenal masses (2–5), varying between 0.35% and 5% for CT examinations (6). Adenomas are the most common adrenal lesions in patients without primary malignancy (1, 7, 8). Although adrenal gland is a common site for distant metastases in patients with known malignancies, adenomas are more common than metastases in these patients. Since the majority of adrenal adenomas are benign and nonfunctional lesions, a clinical and radiological follow-up is sufficient. In nonadenoma lesions, a biopsy or direct surgical resection can be recommended according to the characteristics of the patient. Therefore, determination of whether a detected adrenal mass is an adenoma or nonadenoma is critically important in patient management and changes the form of treatment (9).Computed tomography (CT) is the radiological method of choice in the characterization of adrenal mass lesions (8, 10). Adenomas have low density values in noncontrast CT scans due to their intracytoplasmic fat content (3, 6, 10, 11). However, as much as 30% of adrenal adenomas are poor in fat, thus making it impossible to distinguish them from other masses based on noncontrast CT density (8, 10). In this case, most authors reported that the washout character determined by dynamic contrast-enhanced CT examination differentiates adrenal adenomas from other lesions (10–13). Due to their rich capillary network, adenomas are stained early with the contrast agent, causing them to exhibit a high level of washout (8). However, some nonadenoma lesions, particularly pheochromocytoma, have been reported to show a similar washout pattern (4, 14–18). In the literature, there are many studies that investigated noncontrast and contrast-enhanced CT density and the washout criterion for the differentiation of adenoma and nonadenoma lesions (4, 6, 10–18). However, the scan parameters used in these studies, the characteristics of the devices, the time of wash-in and washout, contrast agent dose, and iodine concentration are not standard and show differences (e.g., 2.5–10 mm collimation; 3–5 mm reconstruction intervals; 80–140 kVp; 150–370 mA; 0.75–3:1 pitch; nonhelical, helical, or multi-slice device; 35–120 s wash-in time; 3–45 min washout time; 100–150 mL contrast agent dose; 300–370 mg/L iodine concentration). In a study using different minutes as washout criteria in the same lesions, different specificity and sensitivity values were found according to the washout time (19). In studies evaluating the effectiveness of adrenal CT in the literature, the reference method also differs. For these reasons, the available literature data is far from being standard. Nonadenoma lesions, which are evaluated as adenoma based on the available data, may cause serious problems in patient management.In the current study, we aimed to investigate the accuracy of density characteristics and washout values of lesions detected on CT at the cutoff values obtained from the literature by taking the pathological results of adrenalectomy specimens as reference to determine the cutoff values of parameters evaluated on CT for the differentiation of adenoma and nonadenoma lesions in the study group.     

Role of magnetic resonance spectroscopy in differential diagnosis of solitary pulmonary lesions

PURPOSEThe aim of our study was to evaluate the availability of magnetic resonance spectroscopy (MRS) for the differentiation of benign or malignant pulmonary nodules and masses.METHODSA total of 59 patients (45 male, 14 female) with pulmonary nodules and masses were included in this prospective study. MRS was applied to the pulmonary lesions of the patients and choline levels were determined. Afterwards CT-guided percutaneous needle biopsy was performed. According to the biopsy results, pulmonary lesions were benign in 25 patients and malignant in 34 patients.RESULTSCholine levels were significantly higher in malignant lesions compared with benign lesions (p < 0.001). When the other conditions were kept constant, the probability of malignancy significantly increased by 17.38-fold (95% CI, 3.78–79.93) in those with choline levels >1.65 μmol/g compared to those with choline levels ≤1.65 μmol/g (p < 0.001).CONCLUSIONMRS is a noninvasive method that can be used in the differential diagnosis of pulmonary nodules and masses.

The majority of the solitary pulmonary nodules have a benign character (1). However, all pulmonary nodules should be considered as malignant lesions unless proven otherwise (2). The differential diagnosis of these lesions may be an important problem in routine medical practice. Computed tomography (CT) is the standard method for the examination of the nodules and mass lesions (3). CT imaging of morphological features like size, margins, and calcification enables the investigation of malignancy (4). However, there is some overlap so that some malignant lesions may appear benign, while some benign nodules may show morphological features typical for malignancy (5). CT imaging for differantial diagnosis have problems like false-negative and false-positive results, over-diagnosis, benign nodule resections, and exposure to radiation (6). Biopsy is the most reliable and effective method for the diagnosis of the pulmonary nodules and mass lesions. However, it may cause serious complications such as pneumothorax, hemoptysis, air embolism, tumor cell seeding and death (7, 8). In addition, the tolerability of this invasive intervention is rather low among patients.Magnetic resonance imaging (MRI) provides information about the tumor morphology and magnetic resonance spectroscopy (MRS) provides biochemical information about the physiology and metabolism of the disease (9). MRS enables molecular analysis of the tissues based on the display of different chemical shifts of certain nuclei in the magnetic field (10). MRS was initially used in neuroradiology for characterization of tumor, stroke, epilepsy, infection, and neurodegenerative diseases. In recent years, it was also introduced in the evaluation of lesions in other organs like breast (11), liver (12), pancreas (13), and prostate (14). There are some in vitro studies in the literature on the use of MRS in lung cancer showing higher lactate and total choline peaks compared with normal tissues (15, 16). Also there is one case report in the literature regarding the feasibility of using MRS in lung cancer (17).The objective of this study was to demonstrate the value of MRS, which is a noninvasive method and does not require a contrast agent, in the differential diagnosis of pulmonary nodules and mass lesions.     

Evaluating the added benefit of CT texture analysis on conventional CT analysis to differentiate benign ovarian cysts

PURPOSEWe aimed to evaluate the benefit of adding CT texture analysis on conventional CT features of benign adnexal cystic lesions, especially in identifying mucinous cystadenoma.METHODSThis retrospective study included patients who underwent surgical removal of benign ovarian cysts (44 mucinous cystadenomas, 32 serous cystadenomas, 16 follicular/simple cysts and 43 endometriotic cysts) at our institution between January 2015 and November 2017. The CT images were independently reviewed by an abdominal radiologist (reviewer 1) and a resident (reviewer 2). Both reviewers recorded the conventional characteristics and performed texture analysis. Based on reviewer 1’s results, two decision trees for differential diagnosis were developed. Reviewer 2’s results were then applied to the decision trees. The diagnostic performances of each reviewer with and without the decision trees were compared.RESULTSSeveral conventional features and texture analysis parameters showed significant differences between mucinous cystadenomas and other benign adnexal cysts. The first decision tree selected septum number and thickness as significant features, whereas the second decision tree selected septum number and the mean values at spatial scaling factor (SSF) 0. Reviewer 1’s performance did not change significantly with or without the use of the decision trees. Reviewer 2’s interpretations were significantly less sensitive than reviewer 1’s interpretations (p = 0.001). However, when aided by the first and second decision trees, Reviewer 2’s interpretations were significantly more sensitive than reviewer 1’s interpretations (86.4%, p < 0.001; 72.7%, p = 0.001).CONCLUSIONThis study suggests the benefit of CT texture analysis on conventional images to differentiate mucinous cystadenoma from other benign adnexal cysts, particularly for less experienced radiologists.

In the assessment of a possible adnexal mass, it is paramount to differentiate benign lesions from malignancies, since their treatment strategies and prognoses drastically differ (1). Approaches to the lesions can even vary among different benign masses. Simple or follicular cysts do not require surgery at all, whereas epithelial tumors need to be resected for pathologic confirmation of their benignity and relief of the symptoms caused by mass effects. The treatment plan for endometriotic cysts varies based on the extent and severity of symptoms.Ultrasonography (US) is often the first imaging method performed in the evaluation of an ovarian lesion because it is widely available, well accepted by the patients, noninvasive and inexpensive (2). Magnetic resonance imaging (MRI) is an essential problem solving tool for characterizing an US-indeterminate adnexal mass, owing to its high resolution with excellent soft tissue contrast, possessing proven superiority over other modalities (1–4). Computed tomography (CT) is generally not intended for primary pelvic or gynecologic evaluation in women, unlike US or MRI (5). Its value in tumor characterization is limited by the detection of fat or calcifications within the lesion and the assessment of its rough shape, which may, but not necessarily, lead to a specific diagnosis (2, 3). In contrast to its suboptimal diagnostic value, recent widespread use of CT has commonly resulted in the incidental initial detection of an adnexal lesion (4–7).Common benign adnexal cystic lesions include functional cysts, serous cystadenomas, mucinous cystadenomas, and endometriotic cysts. Mucinous cystadenomas are characterized as multilocular cystic adnexal masses with variable internal mucinous contents and relatively large size at the time of presentation (2, 3, 8). As with most ovarian masses, it is challenging to make a specific diagnosis of mucinous cystadenoma and exclude other pathologic types, particularly when either US or CT is the only available modality. Two prior studies reported that the detection rates for mucinous cystadenoma using US, CT, and MRI were 50%, 62%, and 70%, respectively (9, 10). On MRI, mucinous tumors classically have a “stained glass appearance” with variable intralocular signal intensities, which allows a more specific differential diagnosis from other tumors than is possible with US and CT (2, 11). However, MRI is too costly and time-consuming to be performed routinely for incidentally found benign diseases.Recent advances in endoscopic surgical techniques have offered new possibilities for the laparoscopic treatment of large ovarian cysts, including mucinous cystadenomas, rather than laparotomy (12). The fluid content of a large cyst must be aspirated before it can be laparoscopically excised and removed (12). However, thick internal materials such as mucin or fat may impair this procedure. One reported case of laparoscopy had to be converted to open laparotomy due to an inability to aspirate the cyst’s liquid contents (13). The laparoscopic removal of large mucinous cystadenomas also poses the risk of spillage, which can cause pseudomyxoma peritonei (14–16). Therefore, it would be helpful to properly analyze the cyst’s internal contents and correctly preoperatively characterize the nature of the lesion to plan the surgery and avoid complications. Because of the limited availability of MRI, we evaluated the utility of CT with added texture analysis to differentiate the internal mucinous contents of ovarian cysts from serous fluid and eventually predict the pathologic diagnosis of the adnexal cystic lesion. Texture analysis is a method used to quantitatively evaluate pixel densities in medical images. Although texture analysis had been used in some previous studies on ovarian cancers, no study has performed texture analysis in ovarian cysts (17–19).Consequently, the purpose of this study is to evaluate the benefit of adding CT texture analysis to conventional CT features when diagnosing benign adnexal cystic lesions, and especially when identifying mucinous cystadenoma.     

Performance of bone tracer for diagnosis and differentiation of transthyretin cardiac amyloidosis: a systematic review and meta-analysis

PURPOSEBone tracers have been validated for many years in detecting transthyretin cardiac amyloidosis (TTR-CA). However, several new studies suggest conflicting results. Our study aimed to systematically evaluate the accuracy of bone radiotracers for diagnosis and differentiation of TTR-CA via a systematic review and meta-analysis.METHODSWe retrieved articles assessing the performance of bone tracer in diagnosing and differentiating TTR-CA from PubMed, the Cochrane Library, ScienceDirect, and DOAJ databases, dating up to 10 July 2020. The meta-analysis was conducted through Stata 16 software, and the risk of bias for the included studies was assessed by the QUADAS-2 tool. Moreover, we made a comprehensive review.RESULTSFourteen articles were included in the systematic review, and 9 in the meta-analysis. The pooled sensitivity was 0.97 (95% confidence interval [95% CI] 0.85–0.99) with heterogeneity (I²=73.5, 95% CI 55.6–91.2), and the specificity was 0.92 (95% CI 0.82–0.96) with heterogeneity (I²=42.0, 95% CI 0.0–86.9). The pooled positive and negative likelihood ratios were 11.49 (95% CI 5.07–26.0) and 0.03 (95% CI 0.01–0.18), respectively. The diagnostic odds ratio was 341 (95% CI 53–2194), and the area under the receiver operating characteristic curve was 0.96 (95% CI 0.94–0.97).CONCLUSIONThe findings evidence that the bone radiotracer is a valuable noninvasive approach that provides high accuracy for diagnosing TTR-CA and plays a modest role in differentiating TTR-CA from immunoglobulin amyloid light-chain cardiac amyloidosis. ^99mTc-HMDP may be more accurate than ^99mTc-PYP, ^99mTc-DPD, and ¹⁸F-NaF in the TTR-CA detecting process, and ¹⁸F-NaF is a promising bone tracer to diagnose and differentiate TTR-CA.

Cardiac amyloidosis (CA) is a group of fatal diseases with poor prognosis (1, 2), which occurs when amyloid (misfolded protein fragments) are deposited in the myocardial extracellular matrix, small blood vessels, and the conduction system (1, 2). The two most frequent types of CA are transthyretin CA (TTR-CA) and immunoglobulin amyloid light-chain CA (AL-CA) (1–5). TTR-CA could be acquired from the aggregation of wildtype TTR (TTRwt), mutant TTR (TTRm), and other types of TTR (3–6). Without typical symptoms, TTR-CA is easily misdiagnosed and underdiagnosed (7, 8), especially in the early stage. From the clinical perspective, doctors often get frustrated in diagnosing TTR-CA and distinguishing TTR-CA from AL-CA, which would delay the optimal treatment and lead to poor prognosis (2).The well-known gold standard for diagnosing TTR-CA depends on endomyocardial biopsy (EMB) (1, 7, 9). Other diagnostic criteria have also been considered (6, 10, 11), such as biopsies from involved organs combined with significant echocardiography findings. Early diagnosis and differentiation of TTR-CA are crucial for the treatment and prognosis (7, 11). Although biopsy combined with additional measures (genotyping or immunohistochemistry) can diagnose and differentiate TTR-CA, biopsy, especially the EMB, cannot be used as a routine procedure due to its possible invasive complications (1–5). Recently, plenty of studies on noninvasive examinations emerged, trying to discuss the early diagnosis of TTR-CA and the differentiation between TTR-CA and AL-CA (10, 12–26). The most representative method is the application of gamma-emitting bone tracers, such as ^99mTc-3,3-diphosphono-1,2-propanodicarboxylic acid (^99mTc-DPD), ^99mTc-pyrophosphate (^99mTc-PYP), and ^99mTc-hydroxymethylene diphosphonate (^99mTc-HMDP) (12–24). Besides, the positron emission tomography (PET) bone tracer ¹⁸F-sodium fluoride (¹⁸F-NaF) has also been used to explore the diagnosis and differentiation of TTR-CA (25, 26).Most studies suggest that bone tracers can diagnose and differentiate TTR-CA. A prior meta-analysis has partly reported the diagnostic accuracy of gamma-emitting bone tracers in TTR-CA (27). Nevertheless, the differentiation of TTR-CA from AL-CA was not fully elaborated, and it did not provide a systematic review and include the positron-emitting bone tracer ¹⁸F-NaF. More importantly, several new studies have indicated that bone radiotracers present suboptimal sensitivity in detecting some TTR-CA (28, 29), which contradicts previous analyses. Therefore, we sought to provide further evidence on the role of bone tracers in TTR-CA diagnosis and CA subtype differentiation by performing a more comprehensive systematic review and a meta-analysis.     

Radiomics signature for predicting postoperative disease-free survival of patients with gastric cancer: development and validation of a predictive nomogram

PURPOSE Radiomics can be used to determine the prognosis of gastric cancer (GC). The objective of this study was to predict the disease-free survival (DFS) after GC surgery based on computed tomography-enhanced images combined with clinical features.METHODS Clinical, imaging, and pathological data of patients who underwent gastric adenocarcinoma resection from June 2015 to May 2019 were retrospectively analyzed. The primary outcome was DFS. Radiomics features were selected using Least Absolute Shrinkage and Selection Operator algorithm and converted into the Rad-score. A nomogram was constructed based on the Rad-score and other clinical factors. The Rad-score and nomogram were validated in the training and validation groups.Results Totally, 179 patients were randomly divided into the training (n = 124) and validation (n = 55) groups. In the training group, validation group, and overall population, the Rad-score could be divided into categories indicating low, moderate, and high risk of recurrence, metastasis, or death; all risk categories showed a significant difference between the training, validation, and overall population groups (all P < .001). Positive lymph nodes (hazard ratio (HR) = 3.07, 95% CI: 1.52-6.23, P = .002), cancer antigen-125 (HR = 3.24, 95% CI: 1.54-6.80, P = .002), and the Rad-score (HR = 0.73, 95% CI: 0.61-0.87, P < .001) were independently associated with DFS. These 3 variables were used to construct a nomogram. In the training group, the areas under the curve at 3 years were 0.758 and 0.776 for the Rad-score and the nomogram, respectively, while they were both 1.000 in the validation group. The net benefit rate was analyzed using a decision curve in the training and validation groups, and the nomogram was superior to the single Rad-score.CONCLUSION Rad-score is an independent factor for DFS after gastrectomy for GC. The nomogram established in this study could be an effective tool for the clinical prediction of DFS after gastrectomy.

Main points

• Rad-score is an independent factor for disease-free survival (DFS) after gastrectomy for gastric cancer.
• Rad-score could be divided into categories indicating low, moderate, and high risk, and each category was associated with distinct DFS.
• Nomogram could be an effective tool for the clinical prediction of DFS after gastrectomy.

Gastric adenocarcinomas are the most common type of stomach cancer.^1,2 There are 1 033 701 new gastric cancer (GC) cases and 872 685 GC-related deaths worldwide in 2018.³ Some regions including Eastern Asia, Eastern Europe, and South America have the highest incidence of GC.^2,4 The treatment management of GC includes surgery, ­chemotherapy, radiation therapy, and targeted therapy.^1,4,5 The 5-year survival of GC patients with localized, regional, and distant-stage diseases are 67%, 31%, and 5%, respectively.^1,4,5The classical prognostic factors for GC include tumor size, lymphovascular invasion, nodal involvement, positive peritoneal cytology, signet ring cell adenocarcinoma,^1,2,4 age, sex,⁶ and obesity.^7,8 TNM (T: primary tumor, N: lymph node, M: distant metastasis) staging system and histopathological classification have been widely used as the prognostic tools for GC, which can help to formulate the treatment strategy.^1,4,5 However, their predictive ability remains limited.^9-11 Novel prognostic biomarkers are also being explored, with similar restrictions.^12-14 In recent years, several functional imaging methods such as computed tomography (CT) perfusion, diffusion-weighted imaging (DWI), and dynamic contrast-enhanced magnetic resonance imaging have been developed. The stomach is a hollow moving organ filled with liquid and gas, and its motion may exacerbate artifacts, resulting in image distortion and ghosting. In addition, concerning the DWI sequence, susceptibility artifacts, distortions, and blurring are inevitable due to the slow traversal through the k-space line and the narrow bandwidth along the phase encoding direction.¹⁵ Among them, emerging radiomics is a promising prognostic tool for GC. Radiomics signatures, which compose of a series of CT texture features, are considered to be a stronger predictive factor, providing additional information beyond the traditional clinical factors.^16,17Previous studies examined the predictive value of radiomics in GC prognosis. A study showed that radiomics could predict recurrence-free survival (RFS) in locally advanced GC.¹⁸ Another radiomics-based model could predict lymphovascular invasion and progression-free survival (PFS) but not overall survival (OS).¹⁹ However, GC radiomics is still in its infancy, facing multiple challenges.²⁰Therefore, this study aimed to predict the disease-free survival (DFS) after GC surgery based on preoperative CT-enhanced images combined with clinical features. The results may help to improve the ability to predict DFS after gastrectomy.     

Evaluation of repeat distal transradial access in the anatomic snuffbox

PURPOSEThere is increasing interest in the distal radial artery in the anatomic snuffbox as an alternative arterial access point, but the durability of the distal radial artery to support repetitive accesses over multiple procedures is not well established. The purpose of this study was therefore to evaluate success rates for repeated left-sided distal transradial access (ldTRA) in the anatomic snuffbox.METHODSIn this single institution retrospective study, all patients undergoing radioembolization treatments from January 1st, 2019 to May 1st, 2020 were prospectively evaluated for ldTRA. ldTRA was performed by 15 different operators. Exclusion criteria were a left radiocephalic hemodialysis fistula, inability to properly position the arm, Barbeau D waveform, or failed prior ldTRA due to tortuosity. Barbeau patterns, arterial sizes, and success rates at the first, second, and third ldTRA were compared.RESULTSFifty patients were evaluated for ldTRA and 44, 39, and 10 underwent one, two, and three ldTRA attempts for a total of 93 procedures. There was no significant change in Barbeau patterns between the first and second (p = 0.13) or first and third (p = 1.0) ldTRA. There was no significant change in artery size between the first (mean, 2.3 mm; range, 1.5–3.4 mm) and second (mean, 2.3 mm; range, 1.6–3.3 mm) (p = 0.59) and first and third (mean, 2.4 mm; range, 1.9–3.3) (p = 0.45) ldTRA. The success rate was not significantly different between the first (93%, 41/44, 95% CI 81%–99%), second (95%, 37/39, 95% CI 83%–99%), and third (100%, 10/10, 95% CI 69%–100%) procedure (p = 1.0). The asymptomatic occlusion rate was 4.1% (2/49, 95% CI 0%–14%), and subsequent ldTRA was successfully completed in both patients with occlusions. There were no hemorrhagic or ischemic complications.CONCLUSIONSuccess rates are indistinguishable among first, second, and third time ldTRA suggesting that this is a durable access point.

The radial artery has been established as a favorable arterial access point for endovascular procedures, with the potential benefits of reduced risk of complications (1) and increased patient comfort (2, 3) compared with the common femoral artery. As an extension to conventional transradial access (cTRA) upstream of the radial styloid, there has recently been interest in distal transradial access (dTRA) in the anatomic snuffbox as an alternative radial artery access point (4, 5).For interventional radiologists several benefits of left-sided distal transradial access (ldTRA) have been proposed. ldTRA with the patient’s hand across the lower abdomen simulates the positioning of right common femoral artery access, a potentially more ergonomic configuration for operators used to working right-handed (6). In this location, the left arm is tucked across the body in a more compact position for cone beam computed tomography (CT) (4). Beyond these ergonomic considerations, it has been suggested that dTRA may reduce the risk of injury to the palmar arch compared with cTRA (4) although this remains to be shown empirically (5).One limitation of dTRA compared with cTRA is that dTRA is less extensively studied. In particular, the durability of this slightly smaller (4) access point which is associated with a slightly higher failure rate (5, 7) for repeat procedures is not well established. Although the occlusion rate is reportedly low (5), few studies have specifically reported outcomes for repeated ldTRA attempts (6, 8).The purpose of this study was to evaluate success rates for repeated left-sided distal transradial access in the anatomic snuffbox.     

Reduction of cardiac motion artifact in step-and-shoot coronary CT angiography with third-generation as compared with second-generation dual-source CT scanners

PURPOSEWe aimed to compare the effects of misregistration (stair-step artifact) occurrence during coronary computed tomography angiography (CCTA) using third- and second-generation dual-source computed tomography (DSCT) scanners.METHODSCCTA was performed in consecutive patients with suspected coronary heart disease. Patients were randomly assigned to two groups and imaged using a third-generation (n=68; group A) or second-generation (n=63; group B) DSCT scanner. Heart rate (HR), heart rate variability (HRV), the number of acquisition steps required, and the anatomical cardiac length of each patient were recorded and compared between the two groups. Qualitative interpretation and analyses were scored with respect to subjective image quality and misregistration (stair-step artifact) by two interpreters. Cohen’s kappa was used to evaluate the consistency between the observers.RESULTSAll CCTA images (100%) on both DSCT scanners yielded satisfactory image quality, with a subjective image quality score of 4.21±0.17. The consistency between the two observers with respect to misregistration and subjective scores were good (κ= 0.91 and 0.92, respectively). Both the number of acquisition steps required and the scan length of each patient in group A differed significantly (p < 0.001) from those in group B; there were significantly fewer artifacts in group A than in group B (p < 0.001). Misregistration artifacts did not correlate with the HRs or HRVs between two required acquisition steps (p > 0.20).CONCLUSIONAs compared with second-generation DSCT, the reduced number of acquisition steps required and the shorter scan length in third-generation DSCT reduced the occurrence of misregistration artifacts in CCTA images.

Coronary computed tomography angiography (CCTA) has gained widespread acceptance as the first choice for noninvasive assessment of a wide variety of cardiac diseases, as it has strong negative-predictive value and is effective in ruling out coronary artery disease in symptomatic patients, particularly those with intermediate risk (1). However, despite recent advances in cardiac computed tomography (CT) technologies, such as faster gantry rotation and an increased number of detector rows, CCTA images remain vulnerable to a number of artifacts due to patient- and technique-specific causes. Artifacts in cardiac CT may cause image degradation and interference in diagnosis (2–4), leading to either underdiagnosis or overtreatment, both of which are associated with increased patient morbidity and mortality (5).Misregistration (stair-step) artifact, a type of cardiac motion artifact, appears when the heart is not in an identical position during consecutive heartbeats, because of arrhythmias (5). Avoiding misregistration artifacts between adjacent acquisition steps remains a challenge in step-and-shoot CCTA (6). Numerous studies have investigated step-and-shoot CCTA with different types of CT scanners. A previous study investigated misregistration artifacts with a 64-slice single-source CT (7), another study investigated image quality obtained with 128-slice dual-source CT (DSCT) (8), while yet another study investigated the effect of heart rate (HR) and heart rate variability (HRV) on image quality when using a 256-slice CT scanner (6). Most guidelines state that decreasing the mean HR and HRV is the most important factor for minimizing cardiac motion artifacts (9, 10), including misregistration artifacts. However, it is not clear whether the incidence of misregistration artifacts would be similar in the new-generation DSCT scanners, with their faster gantry speed and increased Z-coverage.Hence, the aim of this study was to investigate the frequency of occurrence of misregistration artifacts in step-and-shoot CCTA with a third-generation DSCT scanner, as compared with that of a second-generation DSCT scanner.     

CT and clinical features for distinguishing endophytic clear cell renal cell carcinoma from urothelial carcinoma

PURPOSEWe aimed to characterize the clinical and multiphase computed tomography (CT) features of the distinguishing endophytic clear cell renal cell carcinoma (ECCRCC) from endophytic renal urothelial carcinoma (ERUC).METHODSData from 44 patients (35 men and 9 women) with ECCRCC and 21 patients (17 men and 4 women) with ERUC were retrospectively assessed. The mean patient age was 55 years (48.25-59.50 years) and 68 years (63.00-73.00 years), respectively. Univariate and multivariate logistic regression analyses were performed to determine independent predictors for ECCRCC and to construct a predictive model that comprised clinical and CT characteristics for the differential diagnosis of ECCRCC and ERUC. Differential diagnostic performance was assessed using the area under the receiver operating characteristic curve (AUC).RESULTSThe independent predictors of ECCRCC were heterogeneous enhancement (odds ratio [OR] = 0.027, P = .005), hematuria (OR for gross hematuria = 53.995, P = .003; OR for microscopic hematuria = 31.126, P = .027), and an infiltrative growth pattern (OR = 24.301, P = .022). The AUC of the predictive model was 0.938 (P < .001, sensitivity = 84.10%, specificity = 95.20%), which had a better diagnostic performance than heterogeneous enhancement (AUC = 0.766, P = .001, sensitivity = 81.82%, specificity = 71.43%), hematuria (AUC = 0.786, P < .001, sensitivity = 81.82%, specificity = 66.67%), and infiltrative growth pattern (AUC = 0.748, P = .001, sensitivity = 90.48%, specificity = 59.09%).CONCLUSIONThe independent predictors, as well as the predictive model of CT and clinical characteristics, may assist in the differential diagnosis of ECCRCC and ERUC and provide useful information for clinical decision-making.

Main points

• Endophytic clear cell renal cell carcinoma (ECCRCC) and endophytic renal urothelial carcinoma (ERUC) have different computed tomographic (CT) characteristics and clinical features.
• ECCRCC can be distinguished from ERUC by using CT characteristics and clinical data.
• A predictive model may improve the differential diagnosis of ECCRCC and ERUC.

Renal cell carcinoma (RCC) is the most common malignant renal tumor,¹ and 70%-80% of RCC cases are clear cell renal cell carcinoma (ccRCC).^2-5 ccRCCs are usually exophytic renal masses, wherein the tumor center is located in the renal parenchyma or extrarenal fat. However, ccRCCs may also be endophytic masses and may mimic endophytic renal urothelial carcinoma (ERUC).^6,7 Because of their different treatments⁸ and prognoses, the preoperative differentiation of endophytic clear cell renal cell carcinoma (ECCRCC) and ERUC via computed tomography (CT) is challenging for urologists. Similarly, the same location of tumors makes it difficult to distinguish ECCRCC from ERUC before surgery using CT.^9,10 Raza et al.9 expanded the definition of central RCC. Their study included some exophytic RCCs and RCCs in the renal pelvis. Moreover, their study included RCC subtypes other than ccRCC. Bata et al.10 compared the CT values of dynamic enhancement between urothelial carcinoma (UC) and ccRCC, without considering the morphological characteristics of CT imaging.Moreover, endophytic RCCs represent collecting system invasion (CSI), which reportedly results in a poor prognosis.^11-14 A few radiologists have begun to study the CT features of CSI. Karlo et al.¹¹ compared the results of CT-based diagnosis and pathological diagnosis of CSI. Takamatsu et al.¹⁵ explored the correlation between the CT signs of CSI and the survival rate. However, to the best of our knowledge, there are no published studies specifically on CT-based diagnosis to differentiate between ECCRCC and ERUC.The clinical history and the patient’s symptoms are important in the diagnosis of RCC and upper urinary tract UC. Smoking is a risk factor for both RCC and upper urinary tract UC.^16,17 Further, kidney stones may be associated with upper urinary tract UC.^18,19 Flank pain and hematuria are considered typical symptoms of both ccRCC²⁰ and upper urinary tract UC.^21,22 Neither Raza et al.⁹ nor Bata et al.¹⁰ determined the correlation between clinical data and CT for the differential diagnosis of ECCRCC and ERUC.Therefore, we aimed to retrospectively assess and adequately describe the CT characteristics of ECCRCC and ERUC and to determine their correlations with clinical data.     

Establishment of a large animal model for research on transbronchial arterial intervention for lung cancer

PURPOSEWe aimed to evaluate whether bronchial artery can supply a percutaneously inoculated canine transmissible venereal tumor (CTVT) in a lung tumor model.METHODSFresh CTVT tissue blocks were percutaneously inoculated into unilateral or bilateral lungs of six immunosuppressed dogs at the mid zone of the middle or lower lobe. Tumor growth was monitored by computed tomography (CT). Ten weeks after inoculation, pulmonary arterial digital subtraction angiography (DSA), bronchial arterial DSA, transpulmonary arterial contrast-enhanced multislice CT, transbronchial arterial contrast-enhanced multislice CT (BA-MSCT), and transpulmonary arterial lipiodol multislice CT were performed.RESULTSTumor growth was seen in all 10 inoculated sites, with a maximum diameter of 2.734±0.138 cm at 10th week. Bronchial arterial blood supply was evident in 9 nodules on DSA, and was equivocal in one which was later demonstrated on BA-MSCT. No obvious pulmonary arterial blood supply was observed in any of the nodules. Lipiodol deposition was displayed in two of the small distant metastases, which indicated that pulmonary artery was involved in the supply of the metastases.CONCLUSIONOur results demonstrated bronchial arterial blood supply in this new lung cancer model. This model may be used in further research on transbronchial arterial intervention for lung cancer.

Bronchial arterial infusion chemotherapy (BAI) for lung cancer was introduced into clinical practice 50 years ago (1–3). Theoretically, better reductions in tumor size and symptoms, and less adverse effects of anticancer drugs could be achieved with direct infusion of high-density chemotherapeutics into tumors. However, BAI for lung cancer is not widely accepted. In the last two decades, only a few small case series were published in the English literature showing favorable results (4–9). This may be explained by several reasons: the outcomes have not been confirmed, severe complications have been reported (10, 11), the pharmacokinetics of BAI has not been fully understood, the indications and the treatment protocols have not been defined (4, 12). In the near future, the role of BAI or other transbronchial arterial therapy in the combined treatment of lung cancer may be reappraised, given the poor 5-year survival rate of less than 17% despite improvements in therapeutic management (13).Unfortunately, there is currently no large animal lung cancer model for fundamental research on transbronchial arterial therapy. In 2002, Ahrar et al. (14) developed a canine lung tumor model by intra-arterial or percutaneous inoculation of canine transmissible venereal tumor (CTVT) fragments, which was later used for study on percutaneous radiofrequency ablation (15). It is well known that metastatic lung cancer receives blood supply from both pulmonary artery and bronchial artery, with peripheral tumors having a predominant pulmonary circulation and central tumors having a predominant bronchial circulation (16). Our study goal is to evaluate the blood supply of this large animal lung tumor model.     

Scheduling surgery after transarterial embolization: does timing make any difference to intraoperative blood loss for renal cell carcinoma bone metastases?

PURPOSEOur purpose is to clarify the optimal timing of surgery after transarterial embolization (TAE) for renal cell carcinoma (RCC) bone metastases.METHODSThis retrospective study included 41 patients with RCC bone metastases embolized between 2013 and 2019. Different-sized particulate and/or liquid embolic agents were used for TAE. Embolizations were categorized into groups 1–3 according to the interval between TAE and surgery (group 1: <1 day, group 2: 1–3 days, group 3: >3 days). Degree of embolization after TAE was graded visually based on angiographic images (<50%, 50%–75%, 75%–90%, >90%). The relationship between the TAE–surgery interval and intraoperative blood loss (IBL) and the correlation between IBL and embolization grade were examined. Lesion sizes and the relationships among lesion localizations and contrast media usage, intervention time, and IBL were also analyzed.RESULTSForty-six pre-operative TAEs (single lesion at each session) were performed in this study (26 in group 1, 13 in group 2, 7 in group 3). Lesion sizes and distributions were similar between groups (p = 0.897); >75% devascularization was achieved in 40 (TAEs 86.96%), but the IBL showed no correlation with the embolization rate (r=0.032, p = 0.831). The TAE–surgery interval was 1–7 days. The median IBL in group 1 (750 mL; range, 150–3000 mL) was significantly lower than those in the other groups (p = 0.002). Contrast media usage (p = 0.482) and intervention times (p = 0.261) were similar for metastases at different localizations. IBL values after TAE were lower for extremity metastases (p = 0.003).CONCLUSIONBone metastases of RCC are well-vascularized, and to achieve lowest IBL values, surgery should preferably be performed <1 day after TAE.

Renal cell carcinomas (RCCs) are one of the leading causes of cancer-related death worldwide (1). About one-third of RCCs are metastatic at initial diagnosis, and skeletal metastases are the second most frequent type of RCC metastases following lung metastases (43%) (2, 3). Surgical intervention is an option for the treatment of skeletal metastases of RCCs. Although local ablative therapies like thermal ablation may be preferred for tumors <3 cm, systemic chemotherapy and radiotherapy are other options for suitable patients (4). However, RCCs are usually chemo/radio-resistant (50%), and these treatment options are usually favored for palliative intent (3–5).The 5-year overall survival of patients with RCC bone metastases increases when surgical metastasectomy is performed (4). However, since RCC metastases in the skeletal system are usually hypervascular, the operative blood loss could be as high as 18500 mL, which could threaten patients’ lives (6). Transarterial embolization (TAE) of bone tumors was first described in 1975 (7). The operative blood loss can be reduced by adequate devascularization after TAE of the bone metastases (8–11), and a blood loss of less than 3000 mL was defined as clinical success for spinal tumor surgeries (12). Selective TAE of bone metastases can be performed pre-operatively in a single session. Successful embolization can clarify the tumor margins from the surrounding tissue planes, simplifying surgical manipulation of the tumors. Thus, recurrence rates may be lower in patients undergoing this treatment combination (13, 14). Different types of permanent and temporary embolic agents can be selected for TAE of bone metastases. The rationale behind TAE is occlusion of the capillary bed of the tumors; therefore, proximal occlusion should not be preferred due to the presence of numerous collateral capillary vessels (5, 8, 15).This study aimed to clarify the optimal interval between TAE and surgery for RCC bone metastasis to minimize blood loss at the time of surgery.     

Diagnostic performance of radiomics using machine learning algorithms to predict MGMT promoter methylation status in glioma patients: a meta-analysis

PURPOSEWe aimed to assess the diagnostic performance of radiomics using machine learning algorithms to predict the methylation status of the O⁶-methylguanine-DNA methyltransferase (MGMT) promoter in glioma patients.METHODSA comprehensive literature search of PubMed, EMBASE, and Web of Science until 27 July 2021 was performed to identify eligible studies. Stata SE 15.0 and Meta-Disc 1.4 were used for data analysis.RESULTSA total of 15 studies with 1663 patients were included: 5 studies with training and validation cohorts and 10 with only training cohorts. The pooled sensitivity and specificity of machine learning for predicting MGMT promoter methylation in gliomas were 85% (95% CI 79%–90%) and 84% (95% CI 78%–88%) in the training cohort (n=15) and 84% (95% CI 70%–92%) and 78% (95% CI 63%–88%) in the validation cohort (n=5). The AUC was 0.91 (95% CI 0.88–0.93) in the training cohort and 0.88 (95% CI 0.85–0.91) in the validation cohort. The meta-regression demonstrated that magnetic resonance imaging sequences were related to heterogeneity. The sensitivity analysis showed that heterogeneity was reduced by excluding one study with the lowest diagnostic performance.CONCLUSIONThis meta-analysis demonstrated that machine learning is a promising, reliable and repeatable candidate method for predicting MGMT promoter methylation status in glioma and showed a higher performance than non-machine learning methods.

Glioma is the most common type of primary malignant central nervous system (CNS) tumor and accounts for approximately 75% of primary malignant CNS tumors (1). Despite developments in surgery, chemotherapy, and radiotherapy, patients with glioma still suffer an unpleasant prognosis (2). In recent years, increasing attention has been given to molecular markers in patients with glioma. O⁶-methylguanine-DNA methyltransferase (MGMT) is a key gene that encodes a DNA repair enzyme. The methylated MGMT promoter is usually related to better overall survival in temozolomide (TMZ)-treated gliomas (3–5). In addition, the MGMT gene is a potential attractive therapeutic target in the molecularly targeted therapy field (6, 7). Moreover, it has been reported that MGMT promoter methylation status is significantly associated with glioma pseudo-progression in recent studies (8, 9).At present, the approaches for determining MGMT promoter methylation status in glioma are based on surgical sampling (10), which is an invasive procedure and may induce severe complications. The results always take a relatively long period, which may delay important therapeutic decisions and be influenced by intra-tumoral heterogeneity. Thus, identifying a noninvasive, preoperative, and robust means to detect MGMT promoter status is of great significance. Radiomics, which is an advanced imaging analysis technique, utilizes algorithms to automatically extract a large number of data features to convert imaging data into a high-dimensional and mineable feature space (11). Machine learning algorithms have been used to create credible statistical models for classification in radiomics (12), and they have already had a powerful influence on radiology practice and could further change the area of radiology (13–15). For the CNS, magnetic resonance imaging (MRI) is the most common and noninvasive preoperative diagnostic imaging method. Increasing evidence in neuro-oncology has indicated that radiomics features based on MRI can predict the molecular subtype of glioma (16–18).In recent years, a few studies have demonstrated that machine learning performs well in predicting MGMT promoter methylation status in glioma (16, 18–22). However, to our knowledge, no study has performed a systematic assessment of the diagnostic accuracy of machine learning for predicting MGMT promoter methylation status. Thus, our meta-analysis aimed to systematically evaluate the diagnostic efficacy of machine learning for predicting MGMT promoter methylation status in patients with glioma.     

Malpositioned endoscopically inserted biliary stent causing massive hematemesis managed with vascular plug and stenting

A 46-year-old man with a history of hepatitis B cirrhosis and hepatocellular carcinoma (HCC) status post liver transplantation two years ago complicated by HCC recurrence and biliary stenosis presented with hypovolemic shock and melena one month after endoscopic exchange of plastic biliary stents. During endoscopic retrograde cholangiopancreatography, patient was found to have hemobilia and developed uncontrollable bleeding after a common bile duct (CBD) sweep managed by insertion of a stent-graft across major papilla into presumed CBD. The bleeding continued with subsequent negative angiography, and a computed tomography angiography showed malpositioned stent-graft between major papilla and inferior vena cava (IVC). This was successfully managed by the deployment of a vascular plug inside the stent graft and excluding it by deploying a stent across the affected area in IVC.

Endoscopic retrograde cholangiopancreatography (ERCP) is the most common procedure used to diagnose and treat primary pancreaticobiliary disorders and manage postoperative complications. Overall, ERCP has a high technical success and is considered a safe procedure (1). Although with increasing operator experience and advances in technology the safety profile of ERCP is improving, it still could potentially result in severe complications (2). In liver transplant recipients, biliary complications such as biliary stenosis and Oddi sphincter dysfunction are common and can happen in 5%–20% of the patients (3, 4). With the refinement of orthotopic liver transplantation surgical technique, especially donor to recipient biliary duct-to-duct anastomosis and preserving the gastrointestinal anatomy, ERCP plays a central role for the minimally invasive management of biliary complications (5). ERCP outcomes and complications in the general population is very well understood; however, the evidence regarding post-ERCP complications in liver transplant recipients is poor, and few more recent studies suggest an overall complication rate of 9%–15% (5, 6), including a bleeding risk of 2%–3.8% (5, 6) and perforation risk of 0.6% (6), which is higher than what is reported in the general population (7).Interventional radiology (IR) procedures such as percutaneous transhepatic cholangiography and drainage are the second line in managing biliary complications of liver transplant recipients. However, IR still plays a vital role in managing procedural complications, such as bleedings that are challenging to control. We are reporting a rare severe ERCP complication in a liver transplant recipient resulting in uncontrolled bleeding. The bleeding was due to perforation between the common bile duct and inferior vena cava (IVC) and inadvertent deployment of a stent-graft connecting the IVC and duodenum. The complication resulted in massive hematemesis and pulmonary emboli and was successfully managed by an unusual IR approach.     

Correlation of 18F-FDG PET/CT uptake with severity of MRI findings and epidural steroid injection sites in patients with symptomatic degenerative disease of the lumbar spine: a retrospective study

PURPOSEWe aimed to retrospectively correlate ¹⁸F-fluorodeoxyglucose (¹⁸F-FDG) metabolic activity with lumbar spine magnetic resonance imaging (MRI) findings and epidural steroid injection sites in patients with symptomatic degenerative disease of the lumbar spine.METHODSA database search was conducted for patients receiving epidural injections <12 months after a positron emission tomography/computed tomography (PET/CT). Maximum standard uptake values (SUVmax) were measured at the facet joints, neural foramina, and spinal canal. Severity of facet arthrosis, disc degeneration, neuroforaminal, and canal stenosis was determined on MRI using previously described grading scales. Spearman rank coefficient assessed association between PET/CT FDG uptake and severity of MRI findings. The SUVmax was also compared with injection sites.RESULTSTwenty-five patients were included, comprising MRI (n=19) and injection (n=22 patients; 18 interlaminar, 8 transforaminal) groups. Injections were performed an average of 2.6 months after PET/CT. The greatest SUVmax occurred at the L5-S1 spinal canal (mean SUVmax = 2.25). A statistically significant, positive correlation between uptake and grade of spinal canal stenosis was seen only at L4-L5 (r=0.60, p = 0.007). No other significant association was found with spinal canal or neuroforaminal stenosis, or grade of facet joint or disc degeneration. All patients reported symptomatic improvement after injections with mean pain score improvement of 4.4 on a 10-point scale (SD, 2.9). There was moderate agreement between sites of epidural injection and highest SUVmax (κ= 0.591, p < 0.001).CONCLUSION¹⁸F-FDG metabolic activity on PET/CT corresponds with MRI findings about the lumbar spinal column, but there is no significant correlation between severity of MRI findings and radiotracer uptake. Given the moderate agreement between metabolic activity and levels of symptomatic spinal stenosis, further studies are warranted to fully evaluate the diagnostic potential of FDG PET/CT as a surrogate for guiding epidural injections.

¹⁸F-fluorodeoxyglucose (FDG) positron emission tomography/computed tomography (PET/CT) is useful to detect osseous metastases; however, uptake within the musculoskeletal system is frequently incidentally observed related to non-malignant degenerative or inflammatory disease 1–4). Chronic low back pain is extremely common worldwide, with a prevalence of 19.6% among people 20–59 years of age. Image-guided epidural steroid injections can be targeted to address symptomatic focal spinal stenosis (5, 6).Previous studies have examined incidental FDG uptake in the musculoskeletal system in general (1, 7–9) and the spine in particular (10–13), although few have systematically evaluated non-neoplastic uptake as it pertains to patient symptoms. Incidental FDG metabolic activity in the spine is most frequently due to degenerative etiologies involving the intervertebral discs or facet joints (11) with the most common site of uptake at the thoracolumbar junction (10, 13). Despite this, to our knowledge, no study has correlated patterns of radiotracer uptake with MRI findings and patient symptoms.The purpose of our study was therefore to detect possible correlations between FDG metabolic activity and severity of lumbar spine MRI findings as well as epidural injection sites among symptomatic patients.     

Repeat angiography in patients undergoing conventional catheter-directed thrombolysis for submassive pulmonary embolism: a large single-center experience

PURPOSEFew studies have examined conventional catheter-directed thrombolysis (CDT) for the treatment of submassive pulmonary embolism (PE). Moreover, angiographic resolution of thrombus burden following CDT has infrequently been characterized. This study describes a single-center experience treating submassive PE with CDT while utilizing repeat angiography to determine treatment effectiveness.METHODSA retrospective analysis of 140 consecutive patients who underwent CDT for submassive PE from December 2012 to June 2019 was performed. Angiographic resolution of thrombus burden after CDT was reported as high (>75%), moderate (51%–75%), low (26%–50%), or insignificant (≤25%). All angiograms were reviewed by two interventional radiologists. Secondary endpoints included reduction in pulmonary artery pressure (PAP) and clinical outcomes. Bleeding events were classified according to the Society of Interventional Radiology (SIR) adverse event criteria.RESULTSCDT was performed in 140 patients with a mean recombinant tissue plasminogen activator (rtPA) dose of 25.3 mg and a mean treatment time of 26.0 hours. Angiographic resolution of thrombus burden was high in 70.0%, moderate in 19.3%, low in 5.7%, and insignificant in 3.6%; in 2 patients (1.4%) repeat angiography was not performed. Systolic PAP was reduced (47 vs. 35 mmHg, p < 0.001), mean PAP was reduced (25 vs. 21 mmHg, p < 0.001), and 129 patients (92.1%) improved clinically. Patients with high or moderate resolution of thrombus burden had a clinical improvement rate of 95.2%, while patients with low or insignificant thrombus burden resolution had a clinical improvement rate of 76.9% (p = 0.011). Ten patients (7.1%) had hemodynamic or respiratory decompensation requiring mechanical ventilation, systemic thrombolysis, cardiopulmonary resuscitation, or surgical intervention. Seven patients (5.0%) experienced moderate bleeding events and one patient (0.7%) with metastatic disease developed severe gastrointestinal bleeding that resulted in death. Thirty-day mortality was 1.4%.CONCLUSIONIn patients with submassive PE undergoing CDT, angiographic resolution of thrombus burden is a safe and directly observable metric that can be used to determine procedural success. In this study, CDT with repeat angiography was associated with a 5.7% bleeding event rate and 30-day mortality of 1.4%.

Pulmonary embolism (PE) is a major cause of morbidity and mortality in the United States, with an estimated 300 000–600 000 cases per year resulting in 100 000–180 000 deaths (1). Among patients with acute PE, there is significant heterogeneity in clinical presentation. Submassive or intermediate-risk PE comprises at least 25% of PE cases and has a 30-day mortality rate of approximately 2%–3% (2–5). Patients with submassive PE have signs of right ventricle (RV) dysfunction demonstrated on imaging studies or elevated cardiac biomarkers (6). Several catheter-directed therapies for submassive PE have been explored, including conventional catheter-directed thrombolysis (CDT), ultrasound-assisted CDT (UACDT), and various types of mechanical thrombectomy.UACDT has been the subject of multiple investigations and is effective in reducing pulmonary artery pressure (PAP) and right ventricular to left ventricular (RV/LV) ratio in patients with submassive or massive PE (7–9). Despite the recent focus on UACDT, conventional CDT remains an effective treatment option and several authors have demonstrated no differences between UACDT and conventional CDT in terms of thrombolytic dose, bleeding complications, PAP reduction, follow-up echocardiographic findings, or mortality (7, 10–12). Mechanical thrombectomy devices are of particular interest in treating PE since they reduce PAP, RV/LV ratio, and thrombus burden with a low risk of bleeding events (13, 14).Currently there is little in the literature to recommend the routine use of CDT for submassive PE, and endpoints evaluating the effectiveness of CDT in this indication have been inconsistent (15). Several studies have used reductions in PAP or RV/LV ratio as endpoints, while others have focused on improvement of clinical symptoms (8, 9, 16–18). The goal of this study was to describe a single-center experience treating submassive PE with conventional CDT while utilizing repeat angiography to determine treatment effectiveness. In addition, this study attempted to contribute to the standardization of terms that describe angiographic resolution of thrombus burden.     

MR angiography-planned prostatic artery embolization for benign prostatic hyperplasia: single-center retrospective study in 56 patients

PURPOSEWe aimed to evaluate the advantages of magnetic resonance angiography (MRA)-planned prostatic artery embolization (PAE) for benign prostatic hyperplasia (BPH).METHODSIn this retrospective study, MRAs of 56 patients (mean age, 67.23±7.73 years; age range, 47–82 years) who underwent PAE between 2017 and 2018 were evaluated. For inclusion, full information about procedure time and radiation values must have been available. To identify prostatic artery (PA) origin, three-dimensional MRA reconstruction with maximum intensity projection was conducted in every patient. In total, 33 patients completed clinical and imaging follow-up and were included in clinical evaluation.RESULTSThere were 131 PAs with a second PA in 19 pelvic sides. PA origin was correctly identified via MRA in 108 of 131 PAs (82.44%). In patients in which MRA allowed a PA analysis, a significant reduction of the fluoroscopy time (−27.0%, p = 0.028) and of the dose area product (−38.0%, p = 0.003) was detected versus those with no PA analysis prior to PAE. Intervention time was reduced by 13.2%, (p = 0.25). Mean fluoroscopy time was 30.1 min, mean dose area product 27,749 μGy·m², and mean entrance dose 1553 mGy. Technical success was achieved in all 56 patients (100.0%); all patients were embolized on both pelvic sides. The evaluated data documented a significant reduction in international prostate symptom scores (p < 0.001; mean 9.67 points).CONCLUSIONMRA prior to PAE allowed the identification of PA in 82.44% of the cases. MRA-planned PAE is an effective treatment for patients with BPH.

A profound knowledge about pelvic vessel anatomy is essential for achieving successful prostatic artery embolization (PAE), to improve the safety of PAE and to avoid major complications as non-target embolization (1–6). This knowledge can be achieved by using angiographic techniques to show pelvic artery anatomy, although the best method is still controversially discussed. In some studies, computed tomography (CT) angiography (CTA) was used for pre-interventional evaluation as it is described to have high certainty in analyzing prostatic artery (PA) anatomy (1, 3, 7). Other institutes use digital subtraction angiography (DSA) and cone beam CT (CBCT) for analysis without any pre-procedural vessel imaging (8–11). Since peri-interventional DSA findings may be ambiguous and CTA or CBCT would imply additional radiation, magnetic resonance angiography (MRA) seems to be a promising method to analyze PA origin without radiation. However, Maclean et al. (3) recommend CT for planning PAE instead of magnetic resonance imaging (MRI) as the latter is more expensive and more time-consuming. Pisco et al. (5, 12) state that MRA does not have enough resolution for clear identification of PA origin and does not provide the same information as CTA.Currently only a few studies discuss the suitability of MRA for preprocedural planning of PAE. Kim et al. (13) first investigated this subject with a sample size of 17 patients and documented an accuracy of 76.5% for PA origin analysis. However, in this study no clinical evaluation was included. Zhang et al. (4) investigated MRA analysis prior to PAE in a randomized clinical trial with 100 patients. A sensitivity of 91.5% and a significant reduction of procedure time, fluoroscopy time, radiation dose, and contrast medium volume due to pre-interventional MRA were documented. In his review, Prince (14) agrees with Zhang et al. (4) that MRA may be a suitable method for planning PAE.Because of the skeptical comments whether performing MRA prior to PAE is practical on a daily basis in a radiological institution, an assessment of these parameters in a less selective nature was necessary. In addition, contrary to Zhang et al. (4) who used MIP-reconstructions and 5° interval images for their assessment, we used a three-dimensional (3D) reconstruction of the pelvic arterial tree based on the MRA sequences. The main advantage of the 3D reconstruction is that it can be freely rotated in all directions which allowed an easy identification and tracking of the PA.In this study, the advantages and clinical outcome of pre-interventional analysis of PA via MRA as a possible radiation-free planning method and its influence on procedure time and radiation dose were investigated.     

COVID-19 pneumonia: lessons learned,challenges, and preparing for the future

Coronavirus disease 2019 (COVID-19) is a viral disease that causes life-threatening health problems during acute illness, causing a pandemic and millions of deaths. Although computed tomography (CT) was used as a diagnostic tool for COVID-19 in the early period of the pandemic due to the inaccessibility or long duration of the polymerase chain reaction tests, current studies have revealed that CT scan should not be used to diagnose COVID-19. However, radiologic findings are vital in assessing pneumonia severity and investigating complications in patients with COVID-19. Long-term symptoms, also known as long COVID, in people recovering from COVID-19 affect patients’ quality of life and cause global health problems. Herein, we aimed to summarize the lessons learned in COVID-19 pneumonia, the challenges in diagnosing the disease and complications, and the prospects for future studies.

Main points

• Radiologic findings are vital in assessing pneumonia severity, prognosis, the presence of coinfections, and investigating complications in COVID-19.
• Pulmonary thromboembolism is a poor prognostic factor for COVID-19 patients.
• Long-term symptoms experienced by people recovering from COVID-19 (Long COVID) are also significant health problems.
• There is an increased risk of secondary infections, some of which can be fatal, in COVID-19 patients.

At the end of 2019, pneumonia cases of unknown cause emerged in Wuhan, China. Later, scientists determined that this pneumonia agent was a previously unknown betacoronavirus [severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2)].¹ Then, the World Health Organization declared the disease [coronavirus disease 2019 (COVID-19)] caused by SARS-CoV-2 a pandemic.² The most prevalent problems in COVID-19 patients during acute illness are pneumonia, respiratory failure, sepsis, and death. In addition to patient-related factors, coinfections and superinfections are essential causes of poor prognosis in COVID-19 patients during acute illness.³ Radiologic findings are vital in assessing pneumonia severity, prognosis, the presence of coinfections, and investigating complications in COVID-19.^4-6 In addition to acute illness, long-term symptoms experienced by people recovering from COVID-19 are also significant health problems reported more frequently.⁷ Herein, we provide an overview of the lessons learned in patients with COVID-19 pneumonia, the early and long-term complications of COVID-19 pneumonia, and the prospects for future studies.     

Monitoring the therapeutic efficacy of CA4P in the rabbit VX2 liver tumor using dynamic contrast-enhanced MRI

PURPOSEThe present work aims to evaluate whether dynamic contrast-enhanced magnetic resonance imaging (DCE-MRI) can monitor the blocking effect of combretastatin-A4-phosphate (CA4P) on microvessels and assess the therapeutic efficacy.METHODSForty rabbits were implanted VX2 tumor specimens. Two weeks later, serial MRI (T1-weighted imaging, T2-weighted imaging, and DCE) were performed at 0 h, 4 h, 24 h, 3 days, and 7 days after CA4P (10 mg/kg) or saline treatment. The parameters of DCE (K^trans, K_ep, V_e and iAUC60) enhancement of tumor portions were measured. Then all tumor samples were stained to count microvessel density (MVD). Finally, two-way repeated measures ANOVA was used to analyze the difference between and within groups. Correlation between the DCE parameters and MVD was analyzed by using the Pearson correlation and Spearman rank correlation.RESULTSK^trans and iAUC60 values at 4 h after CA4P treatment were significantly lower than those in the control group (D-value: −0.133 min⁻¹, 95%CI: −0.169 to −0.097 min⁻¹, F= 59.109, p < 0.001 for K^trans; D-value: −10.533 mmol/s, 95%CI: −17.147 to −3.919 mmol/s, F= 11.110, and p = 0.003 for iAUC60). In the CA4P group, K^trans and iAUC60 reached the minimum values at 4 h, and both parameters showed significant difference between 4 h and other time points (all p < 0.01). Seven-day values of K^trans (r=0.532, p = 0.016 and r=0.681, p = 0.001, respectively) and iAUC60 (r=0.580, p = 0.007 and r=0.568, p = 0.009, respectively) showed correlation with MVD in both groups, while K_ep and V_e did not show correlation with MVD (p > 0.05).CONCLUSIONThe blocking effect of microvessels after CA4P treatment can be evaluated by DCE-MRI, and the parameters of quantitative K^trans and semi-quantitative iAUC60 can assess the change in tumor angiogenesis noninvasively.

Hepatocellular carcinoma (HCC) has the third highest mortality rate worldwide among cancers (1). Although the 5-year survival rate can reach up to 70% of HCC patients by surgical operation, only less than 30% are suitable for surgery. Transarterial chemoembolization (TACE) treated tumors can stimulate angiogenesis and require repeated treatment (2). As HCC is generally hypervascular, vascular targeting strategies can be used to improve the 5-year survival rate (3).There are two kinds of tumor vascular targeted agents (4): angiogenesis inhibitors (AIs) and vascular disrupting agents (VDAs). AIs can prevent the formation of new blood vessels by inhibiting angiogenesis. VDAs can damage the tumor endothelium directly, shutdown vascular development rapidly and selectively and cause tumor cell ischemia; tumor vascular shutdown occurs within 1 h of administration, and lasts for 24 hours (5, 6). Combretastatin A-4-phosphate (CA4P) is a new-style VDA that progressed into clinical trial stage (7–9).The vascular disrupting effects of VDAs can be assessed by microvessel density (MVD), which is the “gold standard” measurement to evaluate angiogenesis. However, the invasiveness of MVD measurement limits its use (10).During the development of targeted treatments, imaging plays an important role in monitoring the treatment efficacy against malignant tumors (11). Although change in tumor size may not be a reliable method to measure treatment efficacy, plenty of imaging sequences have been developed to overcome the drawbacks of traditional efficacy assessments by size measurement (12–14).DCE-MRI could reflect the microvascular structure and function indirectly, noninvasively and quantitatively, and it has been widely applied to predict and evaluate the treatment response (15). DCE-MRI is expected to be useful in evaluating early vascular disrupting efficacy after CA4P administration. But studies focusing on the changes of DCE parameters at different time points after CA4P administration in the VX2 rabbits have been scarce (16–18). The VX2 liver tumor is supplied by liver artery which is similar with high-grade human HCC, and can be used to simulate the microenvironment of human HCC (19).In this study, we aimed to investigate whether quantitative parameters in DCE-MRI can monitor the change in microvasculature of liver tumors at different time points after CA4P treatment.