Clinical Predictors for Abnormal Renal Bladder Ultrasound in Hospitalized Young Children With a First Febrile Urinary Tract Infection.

BACKGROUND: Physicians often obtain a routine renal bladder ultrasound (RBUS) for young children with a first febrile urinary tract infection (UTI). However, few children are diagnosed with serious anatomic anomalies, and opportunity may exist to take a focused approach to ultrasonography. We aimed to identify characteristics of the child, prenatal ultrasound (PNUS), and illness that could be used to predict an abnormal RBUS and measure the impact of RBUS on management. METHODS: We conducted a single-center prospective cohort study of hospitalized children 0 to 24 months of age with a first febrile UTI from October 1, 2016, to December 23, 2018. Independent variables included characteristics of the child, PNUS, and illness. The primary outcome, abnormal RBUS, was defined through consensus of a multidisciplinary team on the severity of ultrasound findings important to identify during a first UTI. RESULTS: A total of 211 children were included; the median age was 1.0 month (interquartile range 0-2), and 55% were uncircumcised boys. All mothers had a PNUS with 10% being abnormal. Escherichia coli was the pathogen in 85% of UTIs, 20% (n = 39 of 197) had bacteremia, and 7% required intensive care. Abnormal RBUS was found in 36% (n = 76 of 211) of children; of these, 47% (n = 36 of 76) had moderately severe findings and 53% (n = 40 of 76) had severe findings. No significant difference in clinical characteristics was seen among children with and without an abnormal RBUS. One child had Foley catheter placement, and 33% received voiding cystourethrograms, 15% antibiotic prophylaxis, and 16% subspecialty referrals. CONCLUSIONS: No clinical predictors were identified to support a focused approach to RBUS examinations. Future studies should investigate the optimal timing for RBUS.

Allogeneic hematopoietic stem cell transplant for relapsed and refractory non-Hodgkin lymphoma in pediatric patients.

Allogeneic hematopoietic stem cell transplant (HSCT) for relapsed pediatric non-Hodgkin lymphoma (NHL) is often reserved for patients with certain NHL subtypes or high-risk disease whereas the remainder receive autologous HSCT. Given the aggressive nature of pediatric NHL, we performed allogeneic HSCTs for all patients regardless of disease risk. We report overall survival (OS) and prognostic variables in 36 pediatric patients who underwent allogeneic HSCT between 1998 and 2016. OS at 3 years was 67%. The 3-year OS varied based on NHL subtype: 100% for anaplastic large cell lymphoma (n = 14), 63% for diffuse large B-cell lymphoma (n = 8), 17% for lymphoblastic lymphoma (LL; n = 9) and 80% for other subtypes combined (n = 5). Disease status influenced outcome with 3-year OS of 100% for patients in complete remission (n = 15), 59% with partial remission (PR; n = 17), and 0% with progressive/stable disease (n = 3) (P = .004). Of the 17 patients in PR, all 6 with LL died of relapsed disease, whereas the other 11 attained remission after HSCT and remained disease-free. The cumulative incidence of relapse after HSCT for LL was 78% compared with 15% for all other NHL subtypes combined (P < .0001). Cumulative incidence of nonrelapse mortality (NRM) was low in our cohort at 6%. Hence, allogeneic HSCT is a well-tolerated and useful therapeutic option with low rates of NRM and relapse for all NHL subtypes except LL with active disease at HSCT.

Accuracy of surgeon prediction of appendicitis severity in pediatric patients.

PURPOSE: Clinical prediction of disease severity is important as one considers nonoperative management of simple appendicitis. This study assesses the accuracy of surgeons' prediction of appendicitis severity. METHODS: From February to August 2016, pediatric surgeons at a single institution were asked to predict whether patients had simple or complex appendicitis preoperatively based on clinical data, imaging, and general assessment. Receiver operating characteristic curves were generated to determine area under the curve (AUC) and optimal cutoff points of clinical findings for diagnosing simple appendicitis. Outcomes included sensitivity and specificity of variables to identify simple appendicitis. Predictions were compared to operative findings using χ2. A p-value<0.05 was considered statistically significant. RESULTS: Of 125 cases (median age 9 years [IQR 7-13], 58% male), simple appendicitis was predicted in 77 (62%) and complex appendicitis in 48 (38%). Predictions were accurate in 59 (77%) simple cases and 45 (94%) complex cases. Although surgeon prediction was more accurate than individual imaging or clinical findings and was highly sensitive (95%) for diagnosing simple appendicitis, specificity was only 71%. Lower WBC (<15.5 × 103/µL, AUC 0.61, p = 0.05), afebrile (<100.4 °F, AUC 0.86, p < 0.01), and shorter symptom duration (≤ 1.5 days, AUC 0.71, p < 0.001) were associated with simple appendicitis. Of 18 complex cases (14%) inaccurately predicted as simple, 17 (94%) lacked diffuse tenderness, 15 (83%) were well-appearing, 11 (61%) had ultrasound findings of simple appendicitis, 11 (61%) had ≤2 days of symptoms, and 8 (44%) were afebrile (<100.4 °F). CONCLUSION: While surgeon prediction of simple appendicitis is more accurate than ultrasound or clinical data alone, diagnostic accuracy is still limited. TYPE OF STUDY: Prospective survey. LEVEL OF EVIDENCE: II.

Physiologic Ovarian Cysts versus Other Ovarian and Adnexal Pathologic Changes in the Preadolescent and Adolescent Population: US and Surgical Follow-up.

Background Ovarian and adnexal cysts are frequently encountered at US examinations performed in preadolescent and adolescent patients, yet there are few published studies regarding the outcomes of cysts in this population. Purpose To identify characteristics at US that help to distinguish physiologic ovarian cysts from nonphysiologic entities. Materials and Methods Female patients who underwent pelvic US with or without Doppler from January 2009 through December 2013 were identified by using a centralized imaging database. Patients older than 7 years and younger than 18 years with ovarian or adnexal cysts at least 2.5 cm were included. Demographic characteristics, date of surgery, surgical notes, and pathologic reports were extracted from the electronic medical record. Initial and follow-up dates of US, cyst size and complexity, imaging diagnosis, and change on subsequent US images were recorded. Statistical analysis was performed with the Wilcoxon rank sum and Kruskal-Wallis tests for continuous variables and the Fisher exact test for categorical variables. Results Of 754 patients who met inclusion criteria (age, 8-18 years; mean age, 14.6 years ± 1.9 [standard deviation]; mean cyst size, 5 cm ± 3.3), 409 patients underwent complete follow-up that included resolution at imaging (n = 250) or surgery (n = 159). In the patients with complete imaging follow-up, mean time to US documentation of resolution was 194 days ± 321; 59.6% (149 of 250) patients had nonsimple cyst characteristics. One-hundred fifty-nine patients underwent surgical intervention (mean cyst size, 8.5 cm ± 5.3), and 69.8% (111 of 159) of the cysts had simple characteristics. Of the 159 cysts, 100 (62.8%) were defined in the pathologic report as paratubal cysts. Of 409 patients, no malignancies were encountered in this study population with surgical or imaging resolution. Conclusion No malignancies were encountered in the study population and the majority of cysts resolved at follow-up imaging. Large size, persistence, and separability from the ovary were most helpful for identification of nonphysiologic paratubal cysts. © RSNA, 2019.

Pediatric percutaneous renal biopsies: comparison of complications between real-time ultrasound guidance and pre-procedure ultrasound-aided skin-marking techniques.

BACKGROUND: Percutaneous renal biopsy is a commonly performed procedure that guides decision-making for children with renal disease. OBJECTIVE: To compare complications from renal biopsies using real-time ultrasound (US) guidance versus pre-procedure US-aided skin-marking in children. MATERIALS AND METHODS: We conducted a priori power analysis using a risk-adjusted model, which indicated we needed a sample size of 643-714 procedures (effect size: 0.8). Then we retrospectively identified consecutive patients who underwent a percutaneous renal biopsy from Jan. 1, 2012, to Dec. 31, 2016. We categorized complications according to the Society of Interventional Radiology (SIR) criteria and compared rates using the Fisher exact test. We analyzed complication predictors using multivariate regression. RESULTS: The study consisted of 701 percutaneous renal biopsies in 553 patients: 313 used real-time US guidance and 388 used pre-procedure US-aided skin-marking. Among the 254/701 (36%) complications, 56/313 (18%) resulted from real-time US guidance and 198/388 (51%) from pre-procedure US-aided skin-marking (P<0.001). In the US real-time guidance group, 39/56 (70%) complications were SIR A, 8/56 (14%) SIR B, 6/56 (11%) SIR C and 3/56 (5%) SIR D. Among the pre-procedure US-aided skin-marking group, 139/198 (70%) complications were SIR A, 47/198 (24%) SIR B, 11/198 (6%) SIR C and 1/198 (1%) SIR D. Complications between the two groups were significantly different regarding SIR A (P<0.001) and SIR B complications (P<0.001) but not major complications. Multivariate regression demonstrated that complications were higher using US-aided pre-procedure skin-marking (odds ratio [OR]=6.30; 95% confidence interval [CI]=3.86, 10.27) than with US real-time guidance. CONCLUSION: Children and young adults who underwent real-time US-guided percutaneous renal biopsies had significantly fewer minor complications, including those requiring follow-up medical care, compared to those who underwent percutaneous renal biopsies with pre-procedure US-aided skin-marking. No difference was detected in the incidence of major complications.

Response to Lenvatinib in Children with Papillary Thyroid Carcinoma.

BACKGROUND: Papillary thyroid carcinoma (PTC) is the most common thyroid malignancy in children and adolescents. Infrequently, children with PTC may present with or develop disease not amenable to surgery or radioactive iodine (RAI), and systemic therapy may be an option. Lenvatinib is an oral tyrosine kinase inhibitor that is approved by the Food and Drug Administration for the treatment of adults with locally recurrent or metastatic, progressive, RAI-refractory well-differentiated thyroid carcinoma. The effect of lenvatinib in children with PTC has not been reported. PATIENT FINDINGS: Three children with metastatic PTC not amenable or refractory to RAI who responded to lenvatinib are reported. All of them developed respiratory distress requiring oxygen caused by extensive bilateral metastatic pulmonary disease. The first patient is a 14-year-old female who was initially treated with sorafenib for extensive PTC not amenable to upfront surgery or RAI. She had progressive pulmonary disease after five months, and was subsequently treated with oral lenvatinib (14 mg/m2/day). She was weaned to room air after eight weeks. The second patient is a 15-year-old male who was treated with lenvatinib (14 mg/m2/day) for iodine non-avid diffuse pulmonary disease after initial total thyroidectomy and cervical lymph node dissection. He was weaned off oxygen in six weeks. The third patient is a five-year-old male who was treated with lenvatinib (14 mg/m2/day) for pulmonary disease progression 24 months after treatment with total thyroidectomy, cervical lymph node dissection, and RAI treatment. He was weaned off oxygen one day after starting lenvatinib. Two of the patients required dose adjustments secondary to proteinuria. Otherwise, all patients tolerated lenvatinib well. The first two patients remained clinically stable on lenvatinib 23 months and 11 months after initiation of therapy, respectively, and the third patient transitioned to a tumor-specific targeted therapy after one month. SUMMARY: Three pediatric patients are reported with metastatic PTC not amenable or refractory to RAI who achieved a response on lenvatinib. CONCLUSION: Lenvatinib therapy is well tolerated and demonstrated clinical activity in children with advanced PTC. Lenvatinib should be considered in children with PTC that is refractory or not amenable to conventional management.

Modified Friedman technique: a new proposed method of measuring glenoid version in the setting of glenohumeral dysplasia.

BACKGROUND: Glenoid version angles are measured to objectively follow changes related to glenohumeral dysplasia in the setting of brachial plexus birth palsy. Measuring glenoid version on cross-sectional imaging was initially described by Friedman et al. in 1992. Recent literature for non-dysplastic shoulders advocates time-consuming reconstructions and reformations for an accurate assessment of glenoid version. OBJECTIVE: To compare Friedman's original method for measuring glenoid version to a novel technique we developed ("modified Friedman") with the reference standard of true axial reformations. MATERIALS AND METHODS: With institutional review board approval, we retrospectively examined 30 normal and dysplastic shoulders obtained from magnetic resonance imaging examinations of 30 patients with an established diagnosis of brachial plexus birth palsy between January 2012 and September 2017. Four pediatric radiologists performed glenoid version measurements using Friedman's method, the modified Friedman method and a previously described true axial reformation method. The modified Friedman technique better accounts for scapular positioning by selecting a reference point related to the acromion-scapular body interface. Inter-rater reliability and inter-method agreement were assessed using intraclass correlation, paired t-tests and mixed linear model analysis. Equivalence tests between methods were performed per reader. RESULTS: Glenoid version measurements were significantly different when comparing Friedman's method to true axial reformations in normal (-10.8±5.7° [mean±standard deviation] vs. -8.8±5.3°; P≤0.001) and dysplastic shoulders (-34.6±17.7° vs. -28.1±17.5°; P≤0.001). Glenoid version measurements were not significantly different when comparing the modified Friedman's method to true axial reformations in normal (-6.3±5.8° vs. -8.8±5.3°; P=0.06) and dysplastic shoulders (-29.0±18.3° vs. -28.1±17.5°; P=0.06). Friedman's method was not equivalent to true axial reformations for measurements in dysplastic shoulders for all readers (P=0.68, 0.81, 0.86, 0.99); the modified Friedman method was equivalent to of true axial reformations for measurements in dysplastic shoulders for 3 of 4 readers (P≤0.001, P≤0.001, P≤0.001, P=0.10). CONCLUSION: In glenohumeral dysplasia, the modified Friedman method and post-processed true axial reformations provide statistically similar and reproducible values. We propose that our modified Friedman technique can be performed in lieu of post-processed true axial reformations to generate glenoid version measurements.

Renal Ultrasound for Infants Younger Than 2 Months With a Febrile Urinary Tract Infection.

OBJECTIVE: The purpose of this study is to determine the performance of renal ultrasound for detecting vesicoureteral reflux (VUR) and obstructive uropathies in infants younger than 2 months with a febrile urinary tract infection (UTI). MATERIALS AND METHODS: We performed a retrospective cohort study of infants younger than 2 months with fever and culture-proven UTI presenting from July 1, 2008, through December 31, 2011, with renal ultrasound and voiding cystourethrogram (VCUG) performed within 30 days of UTI diagnosis. Two pediatric radiologists independently reviewed the renal ultrasound and VCUG findings. Results of the renal ultrasound were deemed abnormal if collecting system dilation, renal size asymmetry, collecting system duplication, urothelial thickening, ureteral dilation, or bladder anomalies were present. Sensitivity, specificity, positive predictive value (PPV), and negative predictive value (NPV) of renal ultrasound were calculated using VCUG as reference standard. RESULTS: Of the 197 patients included (mean [SD] age, 33 [ 15 ] days; male-to-female ratio, 2:1), 25% (n = 49) had VUR grades I-V, with 16% (n = 31) having VUR grades III-V and 8% (n = 15) having VUR grades IV-V. For grades I-V VUR, sensitivity was 32.7% (95% CI, 20.0-47.5%), specificity was 69.6% (95% CI, 61.5-76.9%), PPV was 26.2% (95% CI, 15.8-39.1%), and NPV was 75.7% (95% CI, 67.6-82.7%). For grades III-V VUR, sensitivity was 51.6% (95% CI, 33.1-69.9%), specificity was 72.9% (95% CI, 65.5-79.5%), PPV was 26.2% (95% CI, 15.8-39.1%), and NPV was 89.0% (95% CI, 82.5-93.7%). For grades IV-V VUR, sensitivity was 86.7% (95% CI, 59.5-98.3%), specificity was 73.6% (95% CI, 66.6-79.9%), PPV was 21.3% (95% CI, 11.9-33.7%), and NPV was 98.5% (95% CI, 94.8-99.8%). No obstructive uropathies were diagnosed by VCUG in patients with normal renal ultrasound findings. CONCLUSION: In infants younger than 2 months, a normal renal ultrasound makes the presence of grades IV and V VUR highly unlikely but does not rule out lower grades of VUR.

Performance of CT examinations in children with suspected acute appendicitis in the community setting: a need for more education.

OBJECTIVE: Despite a recent focus on the preferential use of ultrasound over CT for pediatric appendicitis, most children transferred from community hospitals still undergo diagnostic CT scans. The purpose of this study was to evaluate CT techniques performed for children with acute appendicitis at nonpediatric treatment centers. MATERIALS AND METHODS: All patients treated for acute appendicitis at our tertiary-care pediatric hospital from July 1, 2011, through June 30, 2012, were identified. Patient demographics, imaging modality used to diagnoses appendicitis (CT or ultrasound), location (home or referral institution), and CT technique parameters were collected. The estimated mean organ radiation dose, number of imaging phases, and use of contrast media were evaluated at home and referral institutions. RESULTS: During the study period, 1215 patients underwent appendectomies after imaging, with 442 (36.4%) imaged at referral facilities. Most referral patients received a diagnosis by CT (n=384, 87%), compared with 73 of 773 (9.4%) who received a diagnosis by CT at the home institution. The estimated mean (±SD) organ radiation dose was not statistically significantly different between home and referral institutions (13.5±7.3 vs 12.9±6.4 mGy; p=0.58) for single-phase examinations. Of 384 referral patients, 344 had images available for review. In total, 40% (138/344) of patients from referral centers were imaged with suboptimal CT techniques: 50 delayed phase only, 52 dual phase (eight of which were imaged twice in delayed phase), eight triple phase, and 36 without IV contrast agent. CONCLUSION: CT parameters and radiation doses from single-phase examinations in children with appendicitis were similar at nonpediatric treatment centers and a tertiary care children's hospital. Future educational outreach should focus on optimizing other technical parameters.

Radiographic screening of infants and young children with genetic predisposition for rare malignancies: DICER1 mutations and pleuropulmonary blastoma.

OBJECTIVE: The purpose of this study was to compare the risks of radiation in screening strategies using chest radiographs and CT to detect a rare cancer in a genetically predisposed population against the risks of undetected disease. MATERIALS AND METHODS: A decision analytic model of diagnostic imaging screening strategies was built to predict outcomes and cumulative radiation doses for children with DICER1 mutations screened for pleuropulmonary blastoma. Screening strategies compared were chest radiographs followed by chest CT for a positive radiographic result and CT alone. Screening frequencies ranged from once in 3 years to once every 3 months. BEIR VII (model VII proposed by the Committee on the Biological Effects of Ionizing Radiation) risk tables were used to predict excess cancer mortality for each strategy, and the corresponding loss of life expectancy was calculated using Surveillance Epidemiologic and End Results (SEER) statistics. Loss of life expectancy owing to undetected progressive pleuropulmonary blastoma was estimated on the basis of data from the International Pleuropulmonary Blastoma Registry. Sensitivity analysis was performed for all model parameters. RESULTS: Loss of life expectancy owing to undetected disease in an unscreened population exceeded that owing to radiation-induced cancer for all screening scenarios investigated. Increases in imaging frequency decreased loss of life expectancy for the combined (chest radiographs and CT) screening strategy but increased that for the CT-only strategy. This was because loss of life expectancy for combined screening is dominated by undetected disease, whereas loss of life expectancy for CT screening is dominated by radiation-induced cancers. CONCLUSION: Even for a rare disease such as pleuropulmonary blastoma, radiographic screening of infants and young children with cancer-predisposing mutations may result in improved life expectancy compared with the unscreened population. The benefit of screening will be greater for diseases with a higher screening yield.

Image-guided prediction of pseudocyst formation in pediatric pancreatic trauma.

BACKGROUND: To determine if there is an effective alternative to the current standard of computed tomography (CT) grading of pediatric pancreatic injuries. We hypothesized that the Wong grading scale, which is based on the depth and location of the pancreatic laceration, is more predictive of pseudocyst formation than the American Association for the Surgery of Trauma (AAST) scale after nonoperative management of traumatic pancreatic injury in children. MATERIALS AND METHODS: A retrospective review of children admitted for pancreatic trauma to two level 1 pediatric trauma centers between 2000 and 2012 was conducted. Patients who underwent primary operation were excluded. Initial CT scans were reviewed by two radiologists blinded to clinical outcomes, and injury grades from both scales were assigned. The primary outcome was pseudocyst formation. RESULTS: Fifty-three patients (ages 7 mo-17 y) were included. As per the Wong scale, pseudocysts occurred in 0/20 patients with grade A injuries, 2/17 (12%) with BI/CI injuries, and 9/15 (60%) with BII/CII injuries. Using the AAST scale, pseudocysts developed in 2/27 (7%) patients with grade I/II injuries, 7/20 (35%) patients with III/IV/V injuries, and 1/6 (17%) patients with a scan that was indeterminate between grades II and III. Positive Predictive value, negative predictive value, sensitivity, and specificity for pseudocyst formation were all higher using the Wong scale (AAST/Wong: Positive Predictive value 42%/50%, negative predictive value 91%/94%, sensitivity 80%/82%, and specificity 65%/77%). CONCLUSIONS: The Wong CT grading scale may be superior to the AAST scale for early risk stratification for pseudocyst development after nonoperative management of pediatric pancreatic trauma; however, a larger study is needed for verification of these findings.

Overuse of fluoroscopic gastrostomy studies in a children's hospital.

BACKGROUND: Gastrostomy tubes are often dislodged or exchanged in children. Indications for fluoroscopic examination of gastrostomy location include concern for malposition, dislodgement, leak, or gastric outlet obstruction. We hypothesized that most of the studies obtained at our institution were not ordered for one of the aforementioned indications and do not ultimately affect patient management. METHODS: All fluoroscopic gastrostomy studies performed from January 2011 to December 2012 were reviewed. Transgastric jejunostomy studies were excluded. Patient demographics, indications for the study, elapsed time since placement, imaging findings, and short-term outcomes were recorded. Chi-square analysis was used to evaluate relationships between categorical variables. RESULTS: During the study period, 337 patients who underwent fluoroscopic gastrostomy studies were identified; median age was 2.5 y (0.05-23.8). Sixty-two percent (208/337) of the studies were ordered in asymptomatic patients to confirm tube placement location after routine exchange or replacement. Symptomatic patients accounted for 38% of the studies. Ordering physicians were primarily nonsurgeons (72%, 242/337). Abnormal findings were observed in 4.8% (16/337) of patients, six (1.7%) of whom required an operative intervention. The 2.9% (6/208) abnormal study rate for asymptomatic patients was significantly lower than the 7.9% (10/129) rate in the patients who were evaluated for symptomatic indications (P = 0.03). CONCLUSIONS: Most of the fluoroscopic gastrostomy studies ordered at a tertiary care center did not appear to alter patient care. Development of a standardized management algorithm based on clinical indications is necessary to decrease the number of extraneous gastrostomy studies.

MRI of suspected lower extremity musculoskeletal infection in the pediatric patient: how useful is bilateral imaging?

OBJECTIVE: The purpose of this study was to determine the frequency of bilateral abnormalities in children with suspected lower extremity musculoskeletal infection and the impact of detection of contralateral abnormalities by MRI on patient management. MATERIALS AND METHODS: A retrospective review of 165 consecutive bilateral lower extremity MRI examinations performed for suspected musculoskeletal infection in pediatric patients (64% boys and 36% girls; mean age, 7.5 years; age range, 0-18 years) in 2010 at a children's hospital was performed. Imaging findings were compared with the final clinical diagnosis and management. RESULTS: The MRI examination was normal in 2% (4/165). Osteomyelitis was diagnosed in 33% (54/165) of the MRI examinations; among these examinations 20% (11/54) had both ipsilateral septic arthritis and osteomyelitis, 2% (1/54) had bilateral osteomyelitis, and 67% (111/165) of the examinations were negative for osteomyelitis. Bilateral abnormalities were detected in 20% (22/111) of patients without osteomyelitis, with 18% (4/22) presenting with bilateral signs or symptoms. Abnormalities in the contralateral extremity included myositis (18%, 4/22), stress reaction (18%, 4/22), subcutaneous edema (18%, 4/22), leukemia (14%, 3/22), reactive joint effusion (14%, 3/22), Baker cyst (5%, 1/22), and osteonecrosis (5%, 1/22). Identification of clinically unsuspected abnormalities of the contralateral extremity by MRI was not associated with alterations in medical or surgical management in children with or without osteomyelitis. CONCLUSION: Clinically unsuspected abnormalities of the asymptomatic contralateral lower extremity are common in children referred for MRI of suspected musculoskeletal infection. However, detection of these abnormalities is not associated with alterations in patient management.

Comparison of single- and dual-tracer pharmacokinetic modeling of dynamic contrast-enhanced MRI data using low, medium, and high molecular weight contrast agents.

Pharmacokinetic parameters corresponding to perfused microvascular volume determined from dynamic contrast-enhanced (DCE) MRI data were compared to immunohistochemical measures of microvascular density (MVD) and perfused microvascular density. DCE MRI data from human mammary tumors (MDA-MB-435) implanted in nude mice using low (Gd-DTPA, MW approximately equal 0.6 kDa), medium (Gadomer-17, MW(eff) approximately equal 35 kDa), and high (PG-Gd-DTPA, MW approximately equal 220 kDa) molecular weight contrast agents were analyzed with single- and dual-tracer pharmacokinetic models. MVD values were determined by two manual counting methods, "hot spot" and summed region of interest (SROI). Pharmacokinetic parameters determined using the single-tracer model (Gd-DTPA [n = 15] and Gadomer-17 [n = 13]) did not correlate with MVD measures using either manual counting method. For dual-tracer studies (Gadomer-17/Gd-DTPA [n = 15] and PG-Gd-DTPA/Gd-DTPA [n = 13]), pharmacokinetic parameters demonstrated a statistically significant correlation with MVD determined by the SROI method, but not the "hot spot" method. Ten mice successfully underwent intravital FITC-labeled lectin perfusion with the hemisphere of highest lectin labeling correlating with pharmacokinetic parameter values in 9 of 10 tumors (single-tracer Gd-DTPA [n = 2], single-tracer Gadomer-17 [n = 3], and dual-tracer Gadomer-17/Gd-DTPA [n = 5]). This study demonstrates that dual-tracer DCE MRI studies yield pharmacokinetic parameters that correlate with immunohistochemical measures of MVD.

Determining larval host plant use by a polyphagous lepidopteran through analysis of adult moths for plant secondary metabolites.

Many polyphagous insect species are important economic pests on one or more of their crop hosts. For most important insect pests, the common crop hosts are well-known, but knowledge of weedy and unmanaged hosts is limited. Furthermore, the relative contribution of different hosts to local and regional populations has rarely been ascertained because this requires having some way to determine which plant hosts are the source of the adult moths observed ovipositing in a crop field at a given place and time. One way of determining the larval host of polyphagous pest species is to analyze for several plant-derived chemicals that are each specific to a different small set of related plant species and are preserved in detectable amounts in adult moths. In this paper, we describe novel methods for analyzing adults of the polyphagous lepidopteran, the tobacco budworm (TBW) Heliothis virescens (F.), for plant secondary metabolites, specifically cotinine and gossypol, which are diagnostic for larval feeding on tobacco and cotton, respectively. Cotinine was extracted from individual TBW moths with acetic acid and methanol, then concentrated and analyzed directly by gas chromatography/mass spectrometry (GC/MS). The same moths then were analyzed for bound gossypol by creating a Schiff's base that used aniline, and the resulting dianilino-gossypol complex was quantified using high pressure chromatography coupled with a triple quadrupole mass spectrometer (MS) as the detector. Based on analysis of standards, the detection limit for the cotinine was less than 1.5 ppb by dry weight. Comparable standards were not available for the gossypol derivative so a quantitative limit of detection could not be calculated. When TBW moths reared on known hosts were analyzed for gossypol and/or cotinine, all of the moths reared on tobacco or cotton were correctly identified, although some false positives were recorded with the gossypol method. Analysis of TBW moths of various ages and at various lengths of time after death determined that a significant gossypol signal was detectable in all moths reared on cotton. TBW moths collected from the vicinity of cotton fields in July and August in North Carolina also were analyzed. A much larger portion of the moths were derived from tobacco (6.7-46.4%) than from cotton (0-3.6%) in both months. Thus, these methods can be reliably used to estimate the proportion of TBW derived from noncotton host plants in populations trapped around Bt cotton fields, thereby providing insight into the risk of TBW evolving resistance to Bt cotton.