Cross-sectional imaging of gastric cancer: pearls, pitfalls and lessons learned from multidisciplinary conference.

Gastric cancer is rising in prevalence associated with high mortality, primarily due to late-stage detection, underscoring the imperative for early and precise diagnosis. Etiology involves an interplay of genetic susceptibilities and environmental factors with a prominent role of Helicobacter pylori infection. Due to its often-delayed symptom presentation, prompt and accurate diagnosis is necessary. A multimodal imaging approach, including endoscopic ultrasound (EUS), multi-detector computed tomography (MDCT), and magnetic resonance imaging (MRI) is critical for accurate staging. Each modality contributes unique advantages and limitations, highlighting the importance of integrating diagnostic strategy. Moreover, multidisciplinary conferences offer a vital collaborative platform, bringing together specialists from diverse fields for treatment planning. This synergistic approach not only enhances diagnostic precision but also improves patient outcome. This review highlights the critical role of imaging in diagnosis, staging, and management and advocates for interdisciplinary collaboration in early detection and comprehensive management of gastric cancer, aiming to reduce mortality.

Cross-sectional imaging of mimics of inflammatory bowel disease: not everything is Crohn's disease or ulcerative colitis.

Acute and chronic bowel pathologies can often be mistaken for manifestations of inflammatory bowel disease (IBD), and there are many entities with imaging and clinical features that overlap with IBD, making diagnosis difficult. We describe multiple inflammatory, infectious, neoplastic, and vascular entities with imaging and clinical features that may mimic IBD, and highlight differentiating features to assist in diagnosis.

Incidence of Contrast-Associated Acute Kidney Injury in Renal-Competent COVID-19 Patients Undergoing Computed Chest Angiography.

PURPOSE: COVID-19 infection poses a significant risk of both renal injury and pulmonary embolism, producing a clinical challenge, as the criterion standard examination for pulmonary embolism, computed tomography angiography (CTA), requires the use of nephrotoxic iodinated contrast agents.Our investigation evaluated whether symptomatic COVID-19-positive patients without laboratory evidence of renal impairment are at increased risk for developing contrast-associated acute kidney injury (CA-AKI). METHOD: All COVID-19-positive patients undergoing noncontrast chest computed tomography and CTA at an apex tertiary medical center between March 1 and December 10, 2020, were retrospectively evaluated. A total of 258 renal-competent (estimated glomerular filtration rate >30) patients with baseline and 48- to 72-hour postexamination creatinine measurements were identified and analyzed for incidence of acute kidney injury (AKI) meeting the criteria for CA-AKI. RESULTS: Twenty-five of 191 patients undergoing CTA (13.1%) and 9 of the 67 undergoing noncontrast computed tomography (13.4%) experienced creatinine increases meeting the criteria for CA-AKI. Univariate and multivariate analyses accounting for known AKI risk factors revealed no correlation between iodinated contrast administration and the incidence AKI meeting the criteria for CA-AKI (univariable odds ratio, 0.97 [95% confidence interval, 0.43-2.20]; multivariable odds ratio, 0.97 [95% confidence interval, 0.40-2.36]). CONCLUSIONS: Renal-competent COVID-19 patients undergoing chest CTA may not have an increased risk of AKI. Additional studies are needed to confirm this preliminary finding.

Vascular findings in CTA body and extremity of critically ill COVID-19 patients: commonly encountered vascular complications with review of literature.

The purpose of our review is to discuss the role of CT angiography (CTA) in evaluating a variety of vascular complications in critically ill COVID-19 patients. The COVID-19 pandemic continues to be a worldwide health threat. While COVID-19 pneumonia is the most common and well-recognized presentation of COVID-19, severely ill hospitalized patients often present with extrapulmonary systemic findings. Vascular complications occur not only due to known viral-induced vasculopathy, coagulopathy, and related "cytokine storm," but also due to anticoagulation medication used during hospitalization. There is a paucity of articles describing extrapulmonary vascular findings, especially in critically ill COVID-19 patients. In our article, we discuss commonly encountered vascular imaging findings in the body (chest, abdomen, and pelvis) and extremities, the importance of early radiological detection, and the role of CTA in the management of critically ill COVID-19 patients.

Ultrasound Studies of COVID-19-Positive Patients and Patient Under Investigation: Pandemic Experience of Body Imaging Division at a Tertiary Medical Center.

ABSTRACT: This retrospective study shares our departmental experience of screening of ultrasound (US) requests, triaging of studies, and abbreviated US protocols implemented during the COVID-19 pandemic. For US studies requested in April and May 2020, the following data were collected: type of study, indication, COVID-19 status (positive or patient under investigation [PUI]), decision to perform study, US findings, and location of patient. A total of 196 US studies in 150 patients were included. The median age of patients was 60 years (female: 46.7% [70/150]). At the time of study request, 83 patients (55.3%) were COVID-19-positive and 67 (44.7%) were PUI, of which 8 (11.9%) tested positive after waiting for test result. The most frequently requested study was venous extremity Doppler (51%), followed by right upper quadrant (20.4%), renal (11.7%), and liver duplex (6.6%). After radiologist screening and triage of US requests, 156 studies were performed (79.6%), 15 were postponed until COVID test result (7.6%), and 40 were not performed after discussion with ordering provider (20.4%). Notably, 40.1% of studies performed on COVID-19-positive patients yielded pathological findings, most frequently deep venous thrombosis (18.1%), medical renal disease (7.6%), and gall bladder sludge (5.7%). Abbreviated US protocols were used in 29.4% of studies. In conclusion, US study screening and triage played an important role to optimize care of COVID-19 patients and PUIs.

CT angiography of abdomen and pelvis in critically ill COVID-19 patients: imaging findings and correlation with the CT chest score.

PURPOSE: To assess the spectrum of computed tomography angiogram (CTA) abdominal and pelvic findings in critically ill COVID-19 patients and investigate correlation with CT chest scores. METHODS: An IRB approved retrospective study of CTA of the chest, abdomen and pelvis between dates March 1st to September 15th, 2020 was performed in the hospitalized COVID-19 positive patients. CTA studies of solely the chest were excluded. Medical record review was performed to note patient demographics, CTA scan details and coagulation profile. CTA findings were reviewed to record vascular and non-vascular findings. CT chest was reviewed to calculate CT chest score. Logistic regression analyses were performed to correlate CT chest scores with odds of vascular and other abdomen-pelvis findings. A p < 0.05 was considered statistically significant. RESULTS: A total of 45 consecutive hospitalized COVID-19 positive patients with 61 years mean age and M:F (2:1) gender ratio were evaluated, out of which majority 68.9% (n = 31) had CTA chest, abdomen and pelvis. The most common vascular findings were hematoma 46.7% (n = 21), active extravasation 24.4% (n = 11) and vascular occlusion 17.8% (n = 8). Higher CT chest scores were significantly associated with hematoma/extravasation (OR 1.19, 95% CI 1.07-1.34, p < 0.01). The most common non-vascular abdomen-pelvis findings were seen in organs gallbladder 20% (n = 9), liver 20% (n = 9) followed by kidney 15.6% (n = 7). Higher CT chest scores were significantly associated with bowel findings (OR 1.28, 95% CI 1.01-1.63, p < 0.05) and cholestasis (OR 13.3, 95% CI 1.28-138.9, p < 0.05). CONCLUSION: Patients with moderate to severe COVID-19 pneumonia have significantly higher rate of vascular complications in the abdomen and pelvis.

Reversing the effects of androgen-deprivation therapy in men with metastatic castration-resistant prostate cancer.

OBJECTIVE: To investigate whether bipolar androgen therapy (BAT), involving rapid cyclic administration of high-dose testosterone, as a novel treatment for metastatic castration-resistant prostate cancer (mCRPC) promotes improvements in body composition and associated improvements in lipid profiles and quality of life. PATIENTS AND METHODS: Men from two completed trials with computed tomography imaging at baseline and after three cycles of BAT were included. Cross-sectional areas of psoas muscle, visceral and subcutaneous fat were measured at the L3 vertebral level. Functional Assessment of Chronic Illness Therapy - Fatigue questionnaire and 36-item short-form health survey were used to assess quality of life. RESULTS: The 60 included patients lost a mean (sd) of 7.8 (8.2)% of subcutaneous fat, 9.8 (18.2)% of visceral fat, and gained 12.2 (6.7)% muscle mass. Changes in subcutaneous and visceral fat were positively correlated with each other (Spearman's correlation coefficient 0.58, 95% confidence interval 0.35-0.71) independent of the effects of age, body mass index, and duration of androgen-deprivation therapy. Energy, physical function, and measures of limitations due to physical health were all significantly improved at 3 months. The improvements in body composition were not correlated with decreases in lipid levels or observed improvements in quality of life. CONCLUSIONS: In the present study, BAT was associated with significant improvements in body composition, lipid parameters, and quality of life. This has promising implications for the long-term health of men with mCRPC.

Evaluation of Apparent Diffusion Coefficient as a Predictor of Grade Reclassification in Men on Active Surveillance for Prostate Cancer.

OBJECTIVE: To evaluate the association between apparent diffusion coefficient (ADC) on initial multiparametric MRI (mpMRI) and biopsy grade reclassification (GR) to grade group (GG) ≥2 prostate cancer (CaP) in men on active surveillance (AS) with GG 1 CaP. METHODS: We retrospectively identified 242 AS patients with reported ADC values on their initial mpMRI. ADC value from the index lesion was assessed as an independent predictor of GR using a Cox model. To ease clinical interpretation, we used a log-rank test to establish an ADC cutoff of 1128 × 10-6 mm2/s for Kaplan-Meier analysis. RESULTS: Of the 242 men, 70 underwent GR following initial mpMRI, of which 26 (37%) had GR at the index lesion. There was no significant difference in the median interval between biopsies for men with and without GR (P >.9). Men with GR had significantly lower median ADC than those without GR (P = .01). In multivariable analysis adjusting for age, prostate-specific antigen density, and National Comprehensive Cancer Network risk group, a 100-unit decrease in ADC was associated with a 12% increase in the risk of GR (HR = 1.12, 95% CI: 1.01-1.22, P = .03). Two- and 4-year rates of freedom from GR were significantly lower for men with ADC <1128 × 10-6 mm2/s vs ADC ≥1128 × 10-6 mm2/s (62% and 42% vs 78% and 68%, respectively; P <.001). CONCLUSION: For AS patients, lower ADC on initial mpMRI index lesion is associated with increased risk of GR to GG ≥2 CaP and would be a useful component of multivariable risk prediction tools.

MRI in differentiating malignant versus benign portal vein thrombosis in patients with hepatocellular carcinoma: Value of post contrast imaging with subtraction.

PURPOSE: To evaluate MR imaging parameters including quantitative multiphasic post-contrast enhancement with subtraction and qualitative diffusion weighted imaging (DWI) in differentiating benign versus malignant portal venous thrombosis (PVT) in patients with hepatocellular carcinoma (HCC). METHOD: Radiology reports over a 6-year period ending February 2016 were searched for key words indicating presence of both HCC and PVT on abdominal MRI. 39 patients were identified with PVT characterized as benign or malignant based on pathologic data or serial imaging growth criteria. Image review was performed by two subspecialized radiologists blinded to the diagnosis and medical chart. Signal intensity for regions of interest were recorded within the portal vein thrombus as well as the portal vein on pre-contrast and dynamic post-contrast phases without and with subtraction. Qualitative parameters for DWI and presence of PV expansion were also evaluated. RESULTS: Percent enhancement generated high area under the curve (AUC) for both readers on all non-subtraction phases: arterial (0.95/0.98), portal venous (0.97/0.97) and delayed phase (0.96/0.99) and subtraction phases: arterial (0.91/0.96), portal venous (0.94/0.99) and delayed phases (0.96/0.97). Statistically significant differences were observed between benign and malignant PVT for both readers for PV expansion (p= <0.001/0.006). No qualitative DWI parameter reached statistical significance for both readers. CONCLUSIONS: Post-contrast and subtraction MRI can reliably distinguish malignant from benign PVT in patients with HCC using subtracted or non-subtracted images and at arterial, portal venous, or delayed phase timing.

MDCT evaluation of complications of percutaneous gastrostomy tube placement.

Percutaneous gastrostomy tube placement is a commonly performed procedure to provide enteral alimentation to patients unable to tolerate oral feeds. Percutaneous gastrostomy is a relatively safe procedure, and serious complications like gastrointestinal bleeding, perforated viscus, and adjacent organ injury are rare. The most common complications after gastrostomy tube placement occur early and are usually minor. The purpose of this review article is to describe the techniques of percutaneous gastrostomy tube insertion and imaging protocol for gastrostomy tube evaluation, and describe the early, late, and anytime complications. The article will also illustrate very rare late complications of gastrostomy tube placement like gastro-hepatic fistula, gastro-colic fistula, buried bumper syndrome, and gastrostomy site hernia.

Imaging features of sinonasal tumors on positron emission tomography and magnetic resonance imaging including diffusion weighted imaging: A pictorial review.

INTRODUCTION: Sinonasal inflammatory conditions account for a major component of head and neck pathologies, whereas neoplasms involving the sinonasal region make up only 2-3% of all head and neck lesions. The symptoms of sinonasal tumors are nonspecific; imaging plays a critical role in distinguishing benign and malignant disease and may illustrate characteristic radiological features of specific sinonasal tumors. OBJECTIVE: Aim was to determine the utilization of multimodality imaging, specifically the metabolic information provided by 18-fluorodeoxyglucose positron emission tomography (18F-FDG PET/CT) and diffusivity characteristics seen with diffusion weighted images (DWI) of magnetic resonance imaging (MRI), in a wide range of benign and malignant sinonasal tumors drawn from over 200 sinonasal lesions from our institution and supplemented by the literature. CONCLUSION: In this pictorial essay, we have reviewed common imaging characteristics of frequently encountered in sinonasal tumors and divided them into benign and malignant categories to facilitate creation of focused differential diagnoses.

Positron Emission Tomography-Based Assessment of Metabolic Tumor Volume Predicts Survival after Autologous Hematopoietic Cell Transplantation for Hodgkin Lymphoma.

Autologous hematopoietic cell transplantation (AHCT) is curative for 60% of patients with relapsed or refractory Hodgkin lymphoma (R/R HL). A more precise assessment of the depth of remission before AHCT may help to identify patients likely to benefit from AHCT. We aimed to determine whether positron emission tomography (PET)-based quantitative parameters of total metabolic tumor volume (TMTV), total lesion glycolysis (TLG), and maximal standardized uptake volume (SUVmax) measured before AHCT predict progression-free survival (PFS) after transplant. Pretransplant PET/computed tomography images of 96 consecutive patients with R/R HL were analyzed. Median TMTV, TLG, and SUVmax were 7.97 cm3 (range, 1.3 to 102.1), 23.7 (range, 4.0 to 813.1), and 5.23 (range, 2.7 to 23.2). Two-year PFS in patients with high TMTV (TMTVhigh; more than median; n = 17) was only 12% (95% CI, 1% to 38%) compared with 53% (95% CI, 28% to 73%; P = .05) in patients with TMTVlow (lower or equal to median; n = 17) and 63% (95% CI, 50% to 74%) in 61 patients with no metabolically active tumor (TMTV0; P > .01). In concordance, high TLG (>19) and SUVmax (>4.9) predicted inferior 2-year PFS. In multivariate analysis patients with TMTVhigh had a 3.5-fold higher risk of treatment failure compared with TMTV0/TMTVlow (HR, 3.49; 95% CI, 1.75 to 6.93; P < .01). Deauville (D)-scores of 4 to 5 before AHCT predicted worse PFS compared with D-scores of 1 to 3 (HR, 3.7; 95% CI, 1.92 to 7.28; P < .01). Yet, TMTV and D-scores were disconcordant in 12 subjects; 9 patients in the D4 group with TMTVlow had 2-year PFS of 44% (95% CI, 14% to 72%), which was 2-fold higher than predicted by D4 score. In conclusion, in patients with R/R HL and PET-positive residual disease, TMTVhigh can identify very poor AHCT responders. Patients with TMTVlow, TLG, and SUVmax before AHCT have similar outcomes to those without metabolically active disease.

Fanconi anemia: correlating central nervous system malformations and genetic complementation groups.

BACKGROUND: Congenital central nervous system abnormalities in children with Fanconi anemia are poorly characterized, especially with regard to specific genetic complementation groups. OBJECTIVE: To characterize the impact of genetic complementation groups on central nervous system anatomy. MATERIALS AND METHODS: Through chart review we identified 36 patients with Fanconi anemia with available brain MRIs at the University of Minnesota (average age, 11.3 years; range, 1-43 years; M:F=19:17), which we reviewed and compared to 19 age- and sex-matched controls (average age, 7.9 years; range, 2-18 years; M:F=9:10). Genotypic information was available for 27 patients (15 FA-A, 2 FA-C, 3 FA-G, and 7 FA-D1 [biallelic mutations in BRCA2 gene]). RESULTS: Of the 36 patients, 61% had at least one congenital central nervous system or skull base abnormality. These included hypoplastic clivus (n=12), hypoplastic adenohypophysis (n=11), platybasia (n=8), pontocerebellar hypoplasia (n=7), isolated pontine hypoplasia (n=4), isolated vermis hypoplasia (n=3), and ectopic neurohypophysis (n=6). Average pituitary volume was significantly less in patients with Fanconi anemia (P<0.0001) than in controls. Basal angle was significantly greater in Fanconi anemia patients (P=0.006), but the basal angle of those with FA-D1 was not significantly different from controls (P=0.239). Clivus length was less in the Fanconi anemia group (P=0.002), but significance was only observed in the FA-D1 subgroup (P<0.0001). Of the seven patients meeting criteria for pontocerebellar hypoplasia, six belonged to the FA-D1 group. CONCLUSION: Patients with Fanconi anemia have higher incidences of ectopic neurohypophysis, adenohypophysis hypoplasia, platybasia and other midline central nervous system skull base posterior fossa abnormalities than age- and sex-matched controls. Patients with posterior fossa abnormalities, including pontocerebellar hypoplasia, are more likely to have biallelic BRCA2 mutations.

Three-dimensional Radiologic Assessment of Chemotherapy Response in Ewing Sarcoma Can Be Used to Predict Clinical Outcome.

Purpose To compare the agreement of three-dimensional (3D) tumor measurements for therapeutic response assessment of Ewing sarcoma according to the Children's Oncology Group (COG) criteria, one-dimensional (1D) Response Evaluation Criteria in Solid Tumors (RECIST), and two-dimensional (2D) measurements defined by the World Health Organization (WHO) with tumor volume measurements as the standard of reference and to determine which method correlates best with clinical outcomes. Materials and Methods This retrospective study was approved by the institutional review board of three institutions. Seventy-four patients (mean age ± standard deviation, 14.5 years ± 6.5) with newly diagnosed Ewing sarcoma treated at three medical centers were evaluated. Primary tumor size was assessed on pre- and posttreatment magnetic resonance images according to 1D RECIST, 2D WHO, and 3D COG measurements. Tumor responses were compared with the standard of reference (tumor volume) on the basis of RECIST, COG, and WHO therapeutic response thresholds. Agreement between the percentage reduction measurements of the methods was assessed with concordance correlation, Bland-Altman analysis, and Spearman rank correlation. Agreement between therapeutic responses was assessed with Kendall tau and unweighted κ statistics. Tumor responses were compared with patient survival by using the log-rank test, Kaplan-Meier plots, and Cox regression. Results Agreement with the reference standard was significantly better for 3D measurement than for 1D and 2D measurements on the basis of RECIST and COG therapeutic response thresholds (concordance correlation of 0.41, 0.72, and 0.84 for 1D, 2D, and 3D measurements, respectively; P < .0001). Comparison of overall survival of responders and nonresponders demonstrated P values of .4133, .0112, .0032, and .0027 for 1D, 2D, 3D, and volume measurements, respectively, indicating that higher dimensional measurements were significantly better predictors of overall survival. Conclusion The 3D tumor measurements according to COG are better predictors of therapeutic response of Ewing sarcoma than 1D RECIST or 2D WHO measurements and show a significantly higher correlation with clinical outcomes. (©) RSNA, 2016 Online supplemental material is available for this article.

Progressing Toward a Cohesive Pediatric 18F-FDG PET/MR Protocol: Is Administration of Gadolinium Chelates Necessary?

UNLABELLED: With the increasing availability of integrated PET/MR scanners, the utility and need for MR contrast agents for combined scans is questioned. The purpose of our study was to evaluate whether administration of gadolinium chelates is necessary for evaluation of pediatric tumors on (18)F-FDG PET/MR images. METHODS: First, in 119 pediatric patients with primary and secondary tumors, we used 14 diagnostic criteria to compare the accuracy of several MR sequences: unenhanced T2-weighted fast spin-echo imaging; unenhanced diffusion-weighted imaging; and-before and after gadolinium chelate contrast enhancement-T1-weighted 3-dimensional spoiled gradient echo LAVA (liver acquisition with volume acquisition) imaging. Next, in a subset of 36 patients who had undergone (18)F-FDG PET within 3 wk of MRI, we fused the PET images with the unenhanced T2-weighted MR images (unenhanced (18)F-FDG PET/MRI) and the enhanced T1-weighted MR images (enhanced (18)F-FDG PET/MRI). Using the McNemar test, we compared the accuracy of the two types of fused images using the 14 diagnostic criteria. We also evaluated the concordance between (18)F-FDG avidity and gadolinium chelate enhancement. The standard of reference was histopathologic results, surgical notes, and follow-up imaging. RESULTS: There was no significant difference in diagnostic accuracy between the unenhanced and enhanced MR images. Accordingly, there was no significant difference in diagnostic accuracy between the unenhanced and enhanced (18)F-FDG PET/MR images. (18)F-FDG avidity and gadolinium chelate enhancement were concordant in 30 of the 36 patients and 106 of their 123 tumors. CONCLUSION: Gadolinium chelate administration is not necessary for accurate diagnostic characterization of most solid pediatric malignancies on (18)F-FDG PET/MR images, with the possible exception of focal liver lesions.

Preliminary experience with intravenous gadoxetate disodium as a craniospinal MR contrast agent.

INTRODUCTION: Gadoxetate disodium is a gadolinium-based contrast agent (GBCA) typically used for body imaging, as about 50% of its excretion is via the liver. Its use for craniospinal MRI has not been reported. MATERIALS AND METHODS: Over a 3 years period, 31 adults underwent postcontrast MRI using gadoxetate disodium, each of whom had a relative contraindication to a GBCA, but a GBCA was deemed necessary by the clinical service to direct therapy. Postcontrast T1WI included either gradient-echo (GET1WI, n=12) or spin-echo (SET1WI, n=13) imaging. The contraindication in 29 patients was stage 3-5 chronic kidney disease (CKD) or acute kidney injury (AKI); the other two had normal kidney function, but a history of a reaction to another GBCA (vomiting in one and hypersensitivity in the other). Over a 3 years period, in those patients in whom a GBCA was both deemed necessary and had an estimated GFR (eGFR) of <40 ml/min/1.73 m(2) (i.e., stage 3-5 CKD), both informed consent and nephrology consultation was obtained. A 10 ml dose was given for cranial (n=23), spinal (n=9), and neck/face MRI (n=3), as well as craniocervical MRA (n=6). Three neuroradiologists separately evaluated for normal enhancement in 11 structures. The contrast enhancing percentage (CE%) was measured in 3 structures, and in enhancing lesions, if present. RESULTS: The pre-MRI eGFR was not significantly different from that at 30-90 days (p=0.522) in the 23 patients with an available eGFR at >90 days post-MRI; no patients developed acute kidney injury post-MRI, nor nephrogenic systemic fibrosis. Of the 11 intracranial structures scored, the superior sagittal sinus, pituitary stalk, and atrial choroid plexus enhanced in all 23 patients who underwent brain MRI, with CE%'s of 171.0%, 73.0%, and 69.8%, respectively. The number of patients with enhancing lesions were 3/23 brain MRI's, 8/9 spinal MRI's, 3/3 neck MRI's, and 2/6 craniocervical MRA/MRV's. In 9 spinal MRI's, the basivertebral plexus CE% was 213.7%; in the 7 with spondylodiscitis, the CE% measured 125.8% in enhancing epidural tissue, with a contrast-to-noise ratio (CNR) of 98.0%. CONCLUSION: This preliminary report describes the use of gadoxetate disodium as an alternative GBCA for craniospinal MRI and MRA in the renally impaired, but its efficacy in this regard must be further evaluated prospectively.

Ionising radiation-free whole-body MRI versus (18)F-fluorodeoxyglucose PET/CT scans for children and young adults with cancer: a prospective, non-randomised, single-centre study.

BACKGROUND: Imaging tests are essential for staging of children with cancer. However, CT and radiotracer-based imaging procedures are associated with substantial exposure to ionising radiation and risk of secondary cancer development later in life. Our aim was to create a highly effective, clinically feasible, ionising radiation-free staging method based on whole-body diffusion-weighted MRI and the iron supplement ferumoxytol, used off-label as a contrast agent. METHODS: We compared whole-body diffusion-weighted MRI with standard clinical (18)F-fluorodeoxyglucose ((18)F-FDG) PET/CT scans in children and young adults with malignant lymphomas and sarcomas. Whole-body diffusion-weighted magnetic resonance images were generated by coregistration of colour-encoded ferumoxytol-enhanced whole-body diffusion-weighted MRI scans for tumour detection with ferumoxytol-enhanced T1-weighted MRI scans for anatomical orientation, similar to the concept of integrated (18)F-FDG PET/CT scans. Tumour staging results were compared using Cohen's κ statistics. Histopathology and follow-up imaging served as the standard of reference. Data was assessed in the per-protocol population. This study is registered with ClinicalTrials.gov, number NCT01542879. FINDINGS: 22 of 23 recruited patients were analysed because one patient discontinued before completion of the whole-body scan. Mean exposure to ionising radiation was 12·5 mSv (SD 4·1) for (18)F-FDG PET/CT compared with zero for whole-body diffusion-weighted MRI. (18)F-FDG PET/CT detected 163 of 174 malignant lesions at 1325 anatomical regions and whole-body diffusion-weighted MRI detected 158. Comparing (18)F-FDG PET/CT to whole-body diffusion-weighted MRI, sensitivities were 93·7% (95% CI 89·0-96·8) versus 90·8% (85·5-94·7); specificities 97·7% (95% CI 96·7-98·5) versus 99·5% (98·9-99·8); and diagnostic accuracies 97·2% (93·6-99·4) versus 98·3% (97·4-99·2). Tumour staging results showed very good agreement between both imaging modalities with a κ of 0·93 (0·81-1·00). No adverse events after administration of ferumoxytol were recorded. INTERPRETATION: Ferumoxytol-enhanced whole-body diffusion-weighted MRI could be an alternative to (18)F-FDG PET/CT for staging of children and young adults with cancer that is free of ionising radiation. This new imaging test might help to prevent long-term side-effects from radiographic staging procedures. FUNDING: Thrasher Research Fund and Clinical Health Research Institute at Stanford University.

Perforated appendicitis: an underappreciated mimic of intussusception on ultrasound.

BACKGROUND: We encountered multiple cases in which the US appearance of ruptured appendicitis mimicked intussusception, resulting in diagnostic and therapeutic delay and multiple additional imaging studies. OBJECTIVE: To explore the clinical and imaging discriminatory features between the conditions. MATERIALS AND METHODS: Initial US images in six children (age 16 months to 8 years; 4 boys, 2 girls) were reviewed independently and by consensus by three pediatric radiologists. These findings were compared and correlated with the original reports and subsequent US, fluoroscopic, and CT images and reports. RESULTS: All initial US studies demonstrated a multiple-ring-like appearance (target sign, most apparent on transverse views) with diagnostic consensus supportive of intussusception. In three cases, US findings were somewhat discrepant with clinical concerns. Subsequently, four of the six children had contrast enemas; two were thought to have partial or complete intussusception reduction. Three had a repeat US examination, with recognition of the correct diagnosis. None of the US examinations demonstrated definite intralesional lymph nodes or mesenteric fat, but central echogenicity caused by debris/appendicolith was misinterpreted as fat. All showed perilesional hyperechogenicity that, in retrospect, represented inflamed fat "walling off" of the perforated appendix. There were four CTs, all of which demonstrated a double-ring appearance that correlated with the US target appearance, with inner and outer rings representing the dilated appendix and walled-off appendiceal rupture, respectively. All six children had surgical confirmation of perforated appendicitis. CONCLUSION: Contained perforated appendicitis can produce US findings closely mimicking intussusception. Clinical correlation and careful multiplanar evaluation should allow for sonographic suspicion of perforated appendicitis, which can be confirmed on CT if necessary.

Chest CT in children: anesthesia and atelectasis.

BACKGROUND: There has been an increasing tendency for anesthesiologists to be responsible for providing sedation or anesthesia during chest CT imaging in young children. Anesthesia-related atelectasis noted on chest CT imaging has proven to be a common and troublesome problem, affecting image quality and diagnostic sensitivity. OBJECTIVE: To evaluate the safety and effectiveness of a standardized anesthesia, lung recruitment, controlled-ventilation technique developed at our institution to prevent atelectasis for chest CT imaging in young children. MATERIALS AND METHODS: Fifty-six chest CT scans were obtained in 42 children using a research-based intubation, lung recruitment and controlled-ventilation CT scanning protocol. These studies were compared with 70 non-protocolized chest CT scans under anesthesia taken from 18 of the same children, who were tested at different times, without the specific lung recruitment and controlled-ventilation technique. Two radiology readers scored all inspiratory chest CT scans for overall CT quality and atelectasis. Detailed cardiorespiratory parameters were evaluated at baseline, and during recruitment and inspiratory imaging on 21 controlled-ventilation cases and 8 control cases. RESULTS: Significant differences were noted between groups for both quality and atelectasis scores with optimal scoring demonstrated in the controlled-ventilation cases where 70% were rated very good to excellent quality scans compared with only 24% of non-protocol cases. There was no or minimal atelectasis in 48% of the controlled ventilation cases compared to 51% of non-protocol cases with segmental, multisegmental or lobar atelectasis present. No significant difference in cardiorespiratory parameters was found between controlled ventilation and other chest CT cases and no procedure-related adverse events occurred. CONCLUSION: Controlled-ventilation infant CT scanning under general anesthesia, utilizing intubation and recruitment maneuvers followed by chest CT scans, appears to be a safe and effective method to obtain reliable and reproducible high-quality, motion-free chest CT images in children.

Role of diffusion-weighted imaging in differentiating benign and malignant pediatric abdominal tumors.

BACKGROUND: Solid malignant tumors are more highly cellular than benign lesions and hence have a restricted diffusion of water molecules. OBJECTIVE: To evaluate whether diffusion-weighted MR imaging (DWI) can differentiate between benign and malignant pediatric abdominal tumors. MATERIALS AND METHODS: We retrospectively analyzed DWI scans of 68 consecutive children with 39 benign and 34 malignant abdominal masses. To calculate the apparent diffusion coefficient (ADC) maps and ADC values, we used 1.5-T sequences at TR/TE/b-value of 5,250-7,500/54-64/b = 0, 500 and 3-T sequences at 3,500-4,000/66-73/b = 0, 500, 800. ADC values were compared between benign and malignant and between data derived at 1.5 tesla (T) and at 3 tesla magnetic field strength, using the Mann-Whitney-Wilcoxon test, ANOVA and a receiver operating curve (ROC) analysis. RESULTS: There was no significant difference in ADC values obtained at 1.5 T and 3 T (P = 0.962). Mean ADC values (× 10(-3) mm(2)/s) were 1.07 for solid malignant tumors, 1.6 for solid benign tumors, 2.9 for necrotic portions of malignant tumors and 3.1 for cystic benign lesions. The differences between malignant and benign solid tumors were statistically significant (P = 0.000025). ROC analysis revealed an optimal cut-off ADC value for differentiating malignant and benign solid tumors as 1.29 with excellent inter-observer reliability (alpha score 0.88). CONCLUSION: DWI scans and ADC values can contribute to distinguishing between benign and malignant pediatric abdominal tumors.