David R. Pettersson

Size-appropriate radiation doses in pediatric body CT: a study of regional community adoption in the United States

BackgroundDuring the last decade, there has been a movement in the United States toward utilizing size-appropriate radiation doses for pediatric body CT, with smaller doses given to smaller patients.ObjectiveThis study assesses community adoption of size-appropriate pediatric CT techniques. Size-specific dose estimates (SSDE) in pediatric body scans are compared between community facilities and a university children’s hospital that tailors CT protocols to patient size as advocated by Image Gently.Materials and methodsWe compared 164 pediatric body scans done at community facilities (group X) with 466 children’s hospital scans. Children’s hospital scans were divided into two groups: A, 250 performed with established pediatric weight-based protocols and filtered back projection; B, 216 performed with addition of iterative reconstruction technique and a 60% reduction in volume CT dose index (CTDIvol). SSDE was calculated and differences among groups were compared by regression analysis.ResultsMean SSDE was 1.6 and 3.9 times higher in group X than in groups A and B and 2.5 times higher for group A than group B. A model adjusting for confounders confirmed significant differences between group pairs.ConclusionsRegional community hospitals and imaging centers have not universally adopted child-sized pediatric CT practices. More education and accountability may be necessary to achieve widespread implementation. Since even lower radiation doses are possible with iterative reconstruction technique than with filtered back projection alone, further exploration of the former is encouraged.

Characterization of Laminar Zones in the Mid-Gestation Primate Brain with Magnetic Resonance Imaging and Histological Methods

Distinct populations of progenitor and postmitotic neural and glial cells are stratified in the fetal primate brain across developmentally transient tissue zones between the ventricular and pial surfaces. These zones were originally identified by light microscopy. However, it has subsequently been shown that various forms of magnetic resonance image (MRI) contrast can be used to distinguish layers of developing neural tissue in ex vivo, as well as in vivo (including in utero) conditions. Here we compare mid-gestation rhesus macaque tissue zones identified using histological techniques to ex vivo as well as in utero MRI performed on the same brains. These data are compared to mid-gestation fetal human brain MRI results, obtained in utero. We observe strong similarity between MRI contrast in vivo and post mortem, which facilitates interpretation of in utero images based on the histological characterization performed here. Additionally, we observe differential correspondence between the various forms of ex vivo MRI contrast and microscopy data, with maps of the water apparent diffusion coefficient providing the closest match to histologically-identified lamina of the nonhuman primate brain. Examination of histology and post mortem MRI helps to provide a better understanding of cytoarchitectrual characteristics that give rise to in utero MRI contrast.

Radiological appearances of corpus luteum cysts and their imaging mimics.

PurposeTo review the radiological appearances of corpus luteum cysts and their imaging mimics.ConclusionCorpus luteum cysts are normal post-ovulatory structures seen in the ovaries through the second half of the menstrual cycle and the first trimester of pregnancy. The typical appearance, across all modalities, is of a 1- to 3-cm cyst with a thick crenulated vascularized wall. Occasionally, similar imaging findings may be seen with endometrioma, ectopic pregnancy, tuboovarian abscess, red degeneration of a fibroid, and ovarian neoplasia. In most cases, imaging findings are distinctive and allow for a confident and accurate diagnosis that provides reassurance for patients and referring physicians and avoids costly unnecessary follow-up.

Endorectal multiparametric MRI of the prostate: incremental effect of perfusion imaging on biopsy target identification ☆

PURPOSE To evaluate the incremental effect of perfusion imaging on biopsy target identification at endorectal multiparametric prostate magnetic resonance imaging (MRI). MATERIALS AND METHODS We retrospectively 52 patients who underwent endorectal multiparametric prostate MRI for suspected or untreated prostate cancer. Two readers independently identified biopsy targets without and with perfusion images. RESULTS Reader 1 identified 36 targets without and 39 targets with perfusion imaging (P>.05). The corresponding numbers for reader 2 were 38 and 38, respectively (P=.5). CONCLUSION Perfusion imaging does not significantly increase the number of biopsy targets identified at endorectal multiparametric prostate MRI.

Prostate cancer with a pseudocapsule at MR imaging: a marker of high grade and stage disease?

Clinicopathological correlates of prostate cancer associated with a pseudocapsule at T2-weighted magnetic resonance (MR) imaging are presented in a retrospective series of 15 patients. Of 15 tumors, 14 involved the peripheral zone. Extracapsular extension was seen in 14 cases. Tumor Gleason score was 8 or above in 12 of 15 cases, and ductal type adenocarcinoma was identified in 4 cases. Step section histopathological correlation (n=5) demonstrated that the pseudocapsule corresponded with dense compressive or reactive peritumoral fibrosis. A pseudocapsule around prostate cancer at T2-weighted MR imaging is a rare finding that appears to be associated with high grade and stage disease.

Diagnostic accuracy and clinical outcomes associated with prenatal diagnosis of fetal absent cavum septi pellucidi

Absence of the cavum septi pellucidi (CSP) on prenatal imaging is historically associated with additional anomalies; however, recent cases of isolated absent CSP have also been identified. This study seeks to assess the accuracy of prenatal imaging in evaluating isolated absent CSP and to describe the spectrum of clinical outcomes.

Nigrosome 1 absence in de novo Parkinson disease

A 63-year-old man with 6 months of mild left hand rest tremor and bradykinesia and subtle left wrist cogwheel rigidity was diagnosed with idiopathic Parkinson disease (PD). The most profound neuronal degeneration in PD occurs in nigrosome 1, a lens-shaped substructure of the substantia nigra containing approximately 22,000 cell bodies in each hemi-midbrain, measuring 6 × 6 × 1 mm.1,2 A 7T MRI at the caudal level of red nucleus (figure, A) shows nigrosome 1 signal present in the left nigra and absent in the right, consistent with the clinically affected side. 7T MRI of a healthy 63-year-old with normal bilateral nigrosome 1 signal is shown for comparison (figure, B).

Combined Iron Oxide Nanoparticle Ferumoxytol and Gadolinium Contrast Enhanced MRI Defines Glioblastoma Pseudo-progression

BACKGROUND Noninvasively differentiating therapy-induced pseudoprogression from recurrent disease in patients with glioblastoma is prospectively difficult due to the current lack of a biologically specific imaging metric. Ferumoxytol iron oxide nanoparticle MRI contrast characterizes innate immunity mediated neuroinflammation; therefore, we hypothesized that combined ferumoxytol and gadolinium enhanced MRI could serve as a biomarker of glioblastoma pseudoprogression. METHODS In this institutional review board-approved, retrospective study, we analyzed ferumoxytol and gadolinium contrast enhanced T1-weighted 3T MRI in 45 patients with glioblastoma over multiple clinical timepoints. Isocitrate dehydrogenase 1 (IDH-1) mutational status was characterized by exome sequencing. Sum of products diameter measurements were calculated according to Response Assessment in Neuro-Oncology criteria from both gadolinium and ferumoxytol enhanced sequences. Enhancement mismatch was calculated as the natural log of the ferumoxytol to gadolinium sum of products diameter ratio. Analysis of variance and Students t-test assessed differences in mismatch ratios. P-value <0.05 indicated statistical significance. RESULTS With the development of pseudoprogression we observed a significantly elevated mismatch ratio compared with disease recurrence (P < 0.01) within IDH-1 wild type patients. Patients with IDH-1 mutation demonstrated significantly reduced mismatch ratio with the development of pseudoprogression compared with disease recurrence (P < 0.01). Receiver operator curve analysis demonstrated 100% sensitivity and specificity for the use of mismatch ratios as a diagnostic biomarker of pseudoprogression. CONCLUSION Our study suggests that ferumoxytol to gadolinium contrast mismatch ratios are an MRI biomarker for the diagnosis of pseudoprogression in patients with glioblastoma. This may be due to the unique characterization of therapy-induced neuroinflammation.

The Gibraltar Sign: An Anatomic Landmark for Predicting Transverse Sinus Dominance Laterality on Conventional MRI: The Gibraltar Sign

Physiologic asymmetry of transverse sinus (TS) caliber is common and can lead to misinterpretation of magnetic resonance venography (MRV) studies of the brain. This retrospective study assesses the ability of multiple anatomic features on axial noncontrast T1‐weighted images (T1WIs) of the brain to predict congenital TS dominance.

Nonsurgical Treatment of Delayed-Onset Brachial Plexopathy Due to Hypertrophic Clavicular Callus: A Case Report

Clavicular fractures are common injuries that traditionally are managed nonsurgically without clinically significant sequelae. However, they may develop hypertrophic callus formation that compresses the brachial plexus. These cases may present months to years after initial injury with varying degrees of pain, paresthesia, and weakness on the affected side and usually are treated by surgical resection of the hypertrophic callus. We present a case of brachial plexopathy due to hypertrophic clavicular callus causing weakness and paresthesia. The plexopathy was confirmed with imaging and electrodiagnostic studies. This case was unusual in that resolution of symptoms was achieved nonsurgically.