Extracerebral anatomic blind spots in computed tomography (CT) head: a pictorial review of non-traumatic findings.

CT head has been increasingly performed in the Emergency Department for patients presented with trauma, acute neurological or psychological symptoms. Most of the emergency physicians and radiologists have undergone dedicated training and are capable of identifying and interpreting life-threatening cerebral pathologies. However, as most attention is directed to the brain, the extracerebral non-traumatic pathologies on CT head can easily be overlooked, and some of them harbour clinically significant pathologies. We categorise the extracerebral anatomic landmarks, illustrate and describe the representative pathologies from each category. The purpose of this article is to increase awareness and familiarity on the non-traumatic extracerebral pathologies, with the aim of achieving comprehensive interpretation of CT head.

Correction to: Extracerebral anatomic blind spots in computed tomography (CT) head: a pictorial review of non-traumatic findings.

The original version of this article contains an error. The author name Raphael Shih Zhu Yiin was incorrectly listed as Raphael Shih Zhu Yin. The correct spelling is presented above. The original article has been corrected.

Whole-body diffusion-weighted MRI of normal lymph nodes: prospective apparent diffusion coefficient histogram and nodal distribution analysis in a healthy cohort.

BACKGROUND: Whole body DWI (WB-DWI) enables the identification of lymph nodes for disease evaluation. However, quantitative data of benign lymph nodes across the body are lacking to allow meaningful comparison of diseased states. We evaluated apparent diffusion coefficient (ADC) histogram parameters of all visible lymph nodes in healthy volunteers on WB-DWI and compared differences in nodal ADC values between anatomical regions. METHODS: WB-DWI was performed on a 1.5 T MR system in 20 healthy volunteers (7 female, 13 male, mean age 35 years). The b900 images were evaluated by two radiologists and all visible nodes from the neck to groin areas were segmented and individual nodal median ADC recorded. All segmented nodes in a patient were summated to generate the total nodal volume. Descriptors of the global ADC histogram, derived from individual node median ADCs, including mean, median, skewness and kurtosis were obtained for the global volume and each nodal region per patient. ADC values between nodal regions were compared using one-way ANOVA with Bonferroni post hoc tests and a p-value ≤0.05 was deemed statistically significant. RESULTS: One thousand sixty-seven lymph nodes were analyzed. The global mean and median ADC of all lymph nodes were 1.12 ± 0.27 (10- 3 mm2/s) and 1.09 (10- 3 mm2/s). The average median ADC skewness was 0.25 ± 0.02 and average median ADC kurtosis was 0.34 ± 0.04. The ADC values of intrathoracic, portal and retroperitoneal nodes were significantly higher (1.53 × 10- 3, 1.75 × 10- 3 and 1.58 × 10- 3 mm2/s respectively) than in other regions. Intrathoracic, portal and mesenteric nodes were relatively uncommon, accounting for only 3% of the total nodes segmented. CONCLUSIONS: The global mean and median ADC of all lymph nodes were 1.12 ± 0.27 (10- 3 mm2/s) and 1.09 (10- 3 mm2/s). Intrathoracic, portal and retroperitoneal nodes display significantly higher ADCs. Normal intrathoracic, portal and mesenteric nodes are infrequently visualized on WB-DWI of healthy individuals. TRIAL REGISTRATION: Royal Marsden Hospital committee for clinical research registration number 09/H0801/86, 19.10.2009.

Whole-body diffusion-weighted MRI in lymphoma-comparison of global apparent diffusion coefficient histogram parameters for differentiation of diseased nodes of lymphoma patients from normal lymph nodes of healthy individuals.

BACKGROUND: Morphologic features yield low diagnostic accuracy to distinguish between diseased and normal lymph nodes. The purpose of this study was to compare diseased lymphomatous and normal lymph nodes using global apparent diffusion coefficient (gADC) histogram parameters derived from whole-body diffusion-weighted MRI (WB-DWI). METHODS: 1.5 Tesla WB-DWI of 23 lymphoma patients and 20 healthy volunteers performed between 09/2010 and 07/2015 were retrospectively reviewed. All diseased nodal groups in the lymphoma cohort and all nodes visible on b900 images in healthy volunteers were segmented from neck to groin to generate a total diffusion volume (tDV). A connected component-labelling algorithm separated spatially distinct nodes. Mean, median, skewness, kurtosis, minimum, maximum, interquartile range (IQR), standard deviation (SD), 10th and 90th centile of the gADC distribution were derived from the tDV of each patient/volunteer and from spatially distinct nodes. gADC and regional nodal ADC parameters were compared between malignant and normal nodes using t-tests and ROC curve analyses. A P value ≤0.05 was deemed statistically significant. RESULTS: Mean, median, IQR, 10th and 90th centiles of gADC and regional nodal ADC values were significantly lower in diseased compared with normal lymph nodes. Skewness, kurtosis and tDV were significantly higher in lymphoma. The SD, min and max gADC showed no significant difference between the two groups (P>0.128). The diagnostic accuracies of gADC parameters by AUC from highest to lowest were: 10th centile, mean, median, 90th centile, skewness, kurtosis and IQR. A 10th centile gADC threshold of 0.68×10-3 mm2/s identified diseased lymphomatous nodes with 91% sensitivity and 95% specificity. CONCLUSIONS: WB-DWI derived gADC histogram parameters can distinguish between malignant lymph nodes of lymphoma patients and normal lymph nodes of healthy individuals.

Metronidazole induced encephalopathy: case report and discussion on the differential diagnoses, in particular, Wernicke's encephalopathy.

Metronidazole induced encephalopathy is a rare central nervous system toxicity, which may be completely reversible with prompt cessation of metronidazole usage. We present a case of metronidazole induced encephalopathy in a 59-year-old man with a history of Whipple's procedure for pancreatic neuroendocrine tumour. The characteristic magnetic resonance imaging features of metronidazole induced encephalopathy and its main differential diagnosis, Wernicke's encephalopathy, are discussed.

Spectrum of computed tomography manifestations of appendiceal neoplasms: acute appendicitis and beyond.

Appendiceal neoplasms are rare and often only discovered incidentally during surgery performed for acute appendicitis. Computed tomography (CT) has been demonstrated to be a reliable technique for accurately establishing the preoperative diagnosis of appendiceal neoplasms that manifest as acute appendicitis through the presence of certain imaging findings. Other manifestations of appendiceal neoplasms include appendiceal mass, mucocoele, localised abscess formation, ileus, increasing abdominal girth from pseudomyxoma peritonei, and intussusception. This pictorial essay illustrates varied CT findings of neoplasms of the appendix, with emphasis on the more commonly encountered manifestations of these tumours.