Ruth Eliahou

Determination of Renal Stone Composition with Dual-Energy CT: In Vivo Analysis and Comparison with X-ray Diffraction

PURPOSE To preoperatively assess the composition of urinary stones by using dual-energy computed tomography (CT), with postoperative in vitro x-ray diffraction analysis as the reference standard. MATERIALS AND METHODS Institutional review board approval was obtained, and all participants provided written informed consent. Twenty-seven patients aged 50-64 years with renal stones, who were scheduled for stone extraction with percutaneous nephrolithotomy (PCNL), preoperatively underwent nonenhanced single-source dual-energy multidetector CT with 2-mm section thickness, 1-mm increments, 140 kVp, and 250 mAs. Regions of interest were drawn on low- and high-energy images, and low- and high-energy attenuation ratios were calculated for each stone scanned in vivo. The attenuation ratios for the patients were compared with those for an in vitro stone library phantom model of 37 stones with known chemical compositions. After surgery, the extracted stones were analyzed by using x-ray diffraction. The results of in vivo multidetector CT and ex vivo chemical analysis were compared. RESULTS Dual-energy low- and high-energy attenuation ratios measured with the phantom were less than 1.1 for uric acid, 1.1-1.24 for cystine, and greater than 1.24 for calcified stones. Struvite stones had attenuation ratios that overlapped with calcified stone ratios and thus could not be assessed reliably. Four patients had mixed stones (<75% of a single component), and one patient had a struvite stone. Of 27 patients, 22 (82%) (exact confidence interval [CI]: 68%, 92%) received a correct diagnosis with dual-energy CT: all six (100%; exact CI: 54%, 100%) patients with uric acid stones, 15 (79%; exact CI: 62%, 95%) of the 19 patients with calcium stones, and the one (100%) patient with a cystine stone. The patient with a struvite stone did not receive a correct dual-energy CT-based diagnosis. CONCLUSION Dual-energy multidetector CT may enable accurate in vivo characterization of kidney stone composition.

Critical Analysis of the Performance of Double-Contrast Barium Enema for Detecting Colorectal Polyps ≥ 6 mm in the Era of CT Colonography

OBJECTIVE The purpose of our study was to perform a meta-analysis comparing the performance of double-contrast barium enema (DCBE) with CT colonography (CTC) for the detection of colorectal polyps > or = 6 mm using endoscopy as the gold standard. MATERIALS AND METHODS Prospective DCBE and CTC studies were identified. Percentages of polyps and of patients with polyps > or = 10 mm and 6-9 mm were abstracted. The performance of DCBE versus CTC was determined by separately evaluating each techniques performance versus that of endoscopy, and contrasting the techniques. The I-squared statistic and Fishers exact test were used for heterogeneity, the Cochran-Mantel-Haenszel and the Kruskal-Wallis tests for correlation, and the A(z) test for comparing pooled weighted estimates of performance. RESULTS Eleven studies of DCBE (5,995 patients, 1,548 polyps) and 30 studies of CTC (6,573 patients, 2,348 polyps) fulfilled inclusion criteria. For polyps > or = 10 mm, a 0.121-per-patient sensitivity difference favored CTC (p < 0.0001; DCBE, 0.702 [95% CI, 0.687-0.715]; CTC, 0.823 [0.809-0.836]). For polyps > or = 10 mm, a 0.031-per-polyp sensitivity difference favored CTC (p < 0.0001; DCBE, 0.715 [0.703-0.726]; CTC, 0.746 [0.735-0.757]). For polyps > or = 10 mm, a specificity difference of 0.104 favored CTC (p = 0.001; DCBE, 0.850 [0.847-0.855]; CTC, 0.954 [0.952-0.955]). DCBE was also significantly less sensitive for 6- to 9-mm polyps (p < 0.001). CONCLUSION DCBE has statistically lower sensitivity and specificity than CTC for detecting colorectal polyps > or = 6 mm.

Determination of Renal Stone Composition with Dual-Energy Computed Tomography: An Emerging Application

Urinary tract stone disease is common in the Western world. Nonenhanced computed tomography (CT) is the method of choice for stone diagnosis; however, it has a limited role in predicting stone type. Knowledge of stone composition is currently determined by postoperative assessment of stone fragments. A noninvasive tool for accurate characterization of stone composition would improve patient management. Dual-energy CT aids in the differentiation among calcium, uric acid, and cystine stones. In this review we describe the role of dual-energy CT for in vitro and in vivo analysis of urinary stones. We illustrate the technique, review the literature, and discuss future directions.

Dual-Energy Based Spectral Electronic Cleansing in Non-Cathartic Computed Tomography Colonography: An Emerging Novel Technique

Computed tomography colonography (CTC) with reduced or without bowel catharsis and with fecal tagging has emerged to improve CTC tolerability in patients and their subsequent compliance with colorectal cancer screening. With fecal tagging, electronic cleansing is performed by postprocessing software that removes remnants of contrast material. However, because the technique is threshold based, artifacts that lower the image quality and accuracy of the examination may be noted. Spectral electronic cleansing, based on dual-energy CT and on material-specific cleansing, decreases the number of artifacts and improves image quality. In this review we describe spectral cleansing with reduced catharsis CTC and illustrate its potential benefits.

Effect of benzathine penicillin treatment on antibiotic susceptibility of viridans streptococci in oral flora of patients receiving secondary prophylaxis after rheumatic fever

OBJECTIVE To assess the level of antibiotic resistance of viridans streptococci in the oral flora of children with a history of rheumatic fever, receiving long-term monthly intramuscular benzathine penicillin G prophylaxis. PATIENTS AND METHODS Oral swabs from patients receiving monthly penicillin G prophylaxis for rheumatic fever were cultured and tested for viridans streptococci. The E-test was used to test susceptibility to penicillin G, clindamycin, clarithromycin and rifampin. Findings were compared with samples from healthy children who had not been exposed to antibiotic treatment for at least 2 months. RESULTS Twenty-six patients and 20 control children were included in the study. Duration of intramuscular antibiotic treatment ranged from 5 months to 13.5 years. Sixty isolates of viridans streptococci species were obtained, with a similar distribution in the two groups. Intermediate resistance to penicillin (MIC 0.25-2 mg/L) was documented in 10 of the 32 isolates (31.2%) in the study group, and high resistance in none, compared to seven of 28 isolates (25%) with intermediate or high resistance in the control group (p=NS). All isolates in the study group and all but one in the control group were susceptible to clindamycin, and all isolates from both groups were susceptible to rifampin. One isolate (3.1%) in the study group and two (7.1%) in the control group were resistant to clarithromycin. CONCLUSION Monthly Intramuscular penicillin prophylaxis has no effect on the antibiotic susceptibility of viridans streptococci in oral flora in children with a history of rheumatic fever, receiving secondary prophylaxis after rheumatic fever, regardless of the duration of treatment.

Acute bithalamic infarct manifesting as sleep-like coma: A diagnostic challenge.

Bilateral thalamic infarction (BTI) typically presents as a sleep-like coma (SLC) without localizing signs, posing a diagnostic challenge that may lead the treating physician to search for toxic or metabolic causes and delay treatment. We review our experience with BTI of different etiologies, and emphasize the critical role of timely imaging, diagnosis, and management in a series of 12 patients with a presentation of SLC and acute BTI who were managed in our Medical Centers from 2006-2015. In 11/12, urgent head CT scans showed normal brain tissue, while diffusion-weighted (DWI) MRI revealed symmetric bilateral thalamic hyperintense lesions with variable degrees of brainstem involvement. In 1/12, CT scans revealed a contralateral subacute stroke from a thalamic infarct 1month earlier with a unilateral hyperintense lesion on DWI-MRI. From clinical and imaging findings (DWI-MRI, CT angiography and venography), etiology was attributed to embolic causes (cardio-embolism, artery-to-artery mechanism), small vessel disease, or deep sinus vein thrombosis secondary to dural arteriovenous (AV) fistula. Three patients had good outcomes after prompt diagnosis and optimal treatment in <3hours (intravenous tissue plasminogen activator in two patients cardio-embolic etiology and neuro-endovascular repair in one patient with venous infarction due to a dural AV fistula). The diagnosis was made beyond the therapeutic window in seven patients, who were left with significant neurological sequelae. Higher awareness of BTI presenting as SLC is warranted. Optimal patient management includes urgent DWI-MRI. In cases of BTI, further imaging workup is indicated to provide a comprehensive assessment for etiology. Early diagnosis and prompt, targeted intervention are crucial.

Iatrogenic intracranial hypotension and cerebral venous thrombosis.

OBJECTIVE To assess the manifestations of cerebral venous thrombosis (CVT) associated with intracranial hypotension (IH) following lumbar puncture (LP) or spinal anesthesia (SA). METHODS Adult patients with acute CVT unrelated to infection, neurosurgery, or otolaryngological surgery were identified. CVT manifesting within 21days after LP/SA was considered associated with iatrogenic IH. Presentation of patients with and without associate IH was compared. RESULTS 42 patients were included. 11/42 who had undergone LP/SA presented symptoms and imaging characteristics of IH; 31 had no evidence of IH. Those with IH were more often females (11/11 vs. 21/31, p=0.03), presented sooner after symptom onset (6.0±2.2 vs. 15.6±14days, p=0.002), and rates of venous infarction (45% vs. 23%) and seizures (27% vs. 10%) appeared somewhat elevated (p<0.15). Patients with CVT associated with IH had significantly more cortical vein thrombi (55% vs. 16%, p=0.02). Thrombi were significantly shorter in patients with IH (102±113mm vs. 246±133mm, p=0.002). CONCLUSION Patients with CVT secondary to IH were typically younger females, and presented with a more acute and severe course with frequent venous infarcts. Although thrombi in the IH group were less extensive, they were more often symptomatic.

Drops in Barometric Pressure Are Associated with Deep Intracerebral Hemorrhage.

BACKGROUND AND PURPOSE The objective of this study is to assess the effects of changes in barometric pressure and outdoor temperature on the incidence of different subtypes of intracerebral hemorrhage (ICH). METHODS Consecutive patients with primary supratentorial ICH were included. All patients resided in the same geographic area. We compared patients with subcortical ICH to those with cortical ICH. Meteorological data were continuously accrued. High-risk ICH days were defined as those on which 1 or more patients with ICH were admitted and compared to non-high-risk days. We analyzed the relationship between spontaneous ICH location and averaged daily atmospheric pressures and temperatures. RESULTS We included 206 patients (147 with deep ICH and 59 with lobar ICH). Patients with deep ICH were younger (P < .001), more often had histories of diabetes, smoking and previous lacunar strokes, and were more often male (P < .01 for all). Drops in mean air pressure 2 days prior to the ictus were associated with deep but not lobar ICH (P = .006). Deep ICH clustered during February months in parallel with larger changes in barometric pressures (P < .001). CONCLUSIONS Drops in daily atmospheric pressures were associated with deep but not cortical ICH, suggesting a link to hypertensive etiology. Changes in barometric pressures were also associated with higher monthly frequencies of ICH.

Early hydrocephalus in Listeria meningitis: Case report and review of the literature

Highlights • Early hydrocephalus is common in L. monocytogenes meningitis.• Suspect hydrocephalus when neurological deterioration occurs few days after initial presentation, especially when treatment was not directed against L. monocytogenes.• Appropriate antimicrobial treatment and surgical ventriculostomy usually result in a favorable outcome.• Meningitis complicated by hydrocephalus should raise to possibility of L. monocytogenes.

Temporal Dissociation of Neocortical and Hippocampal Contributions to Mental Time Travel Using Intracranial Recordings in Humans

In mental time travel (MTT) one is “traveling” back-and-forth in time, remembering, and imagining events. Despite intensive research regarding memory processes in the hippocampus, it was only recently shown that the hippocampus plays an essential role in encoding the temporal order of events remembered, and therefore plays an important role in MTT. Does it also encode the temporal relations of these events to the remembering self? We asked patients undergoing pre-surgical evaluation with depth electrodes penetrating the temporal lobes bilaterally toward the hippocampus to project themselves in time to a past, future, or present time-point, and then make judgments regarding various events. Classification analysis of intracranial evoked potentials revealed clear temporal dissociation in the left hemisphere between lateral-temporal electrodes, activated at ~100–300 ms, and hippocampal electrodes, activated at ~400–600 ms. This dissociation may suggest a division of labor in the temporal lobe during self-projection in time, hinting toward the different roles of the lateral-temporal cortex and the hippocampus in MTT and the temporal organization of the related events with respect to the experiencing self.