Savvas Nicolaou

Hand-Held Thoracic Sonography for Detecting Post-Traumatic Pneumothoraces: The Extended Focused Assessment With Sonography For Trauma (EFAST)

BACKGROUND Thoracic ultrasound (EFAST) has shown promise in inferring the presence of post-traumatic pneumothoraces (PTXs) and may have a particular value in identifying occult pneumothoraces (OPTXs) missed by the AP supine chest radiograph (CXR). However, the diagnostic utility of hand-held US has not been previously evaluated in this role. METHODS Thoracic US examinations were performed during the initial resuscitation of injured patients at a provincial trauma referral center. A high frequency linear transducer and a 2.4 kg US attached to a video-recorder were used. Real-time EFAST examinations for PTXs were blindly compared with the subsequent results of CXRs, a composite standard (CXR, chest and abdominal CT scans, clinical course, and invasive interventions), and a CT gold standard (CT only). Charts were reviewed for in-hospital outcomes and follow-up. RESULTS There were 225 eligible patients (207 blunt, 18 penetrating); 17 were excluded from the US examination because of battery failure or a lost probe. Sixty-five (65) PTXs were detected in 52 patients (22% of patients), 41 (63%) being occult to CXR in 33 patients (14.2% whole population, 24.6% of those with a CT). The US and CXR agreed in 186 (89.4%) of patients, EFAST was better in 16 (7.7%), and CXR better in 6 (2.9%). Compared with the composite standard, the sensitivity of EFAST was 58.9% with a likelihood ratio of a positive test (LR+) of 69.7 and a specificity of 99.1%. Comparing EFAST directly to CXR, by looking at each of 266 lung fields with the benefit of the CT gold standard, the EFAST showed higher sensitivity over CXR (48.8% versus 20.9%). Both exams had a very high specificity (99.6% and 98.7%), and very predictive LR+ (46.7 and 36.3). CONCLUSION EFAST has comparable specificity to CXR but is more sensitive for the detection of OPTXs after trauma. Positive EFAST findings should be addressed either clinically or with CT depending on hemodynamic stability. CT should be used if detection of all PTXs is desired.

Dual Energy Computed Tomography in tophaceous gout

Objective: To evaluate the potential utility of a dual energy CT (DECT) scan in assessing urate deposits among patients with tophaceous gout, and obtain computerised quantification of tophus volume in peripheral joints. Methods: 20 consecutive patients with tophaceous gout and 10 control patients with other arthritic conditions were included. DECT scans were performed using a renal stone colour-coding protocol that specifically assessed the chemical composition of the material (ie, urate coloured in red, calcium coloured in blue). An automated volumetric assessment of DECT was used to measure the volume of urate deposits in all peripheral joint areas. Results: All 20 patients with gout showed red colour-coded urate deposits on their DECT scans, whereas none of 10 controls showed urate deposits. DECT scans revealed a total of 440 areas of urate deposition in 20 patients, whereas physical examination showed 111 areas of urate deposition (mean 22 vs 6 per patient, respectively, p<0.001). Total urate volume in a given patient ranged from 0.63 cm3 to 249.13 cm3, with a mean of 40.20 cm3. Conclusions: DECT scans can produce obvious colour displays for urate deposits and help to identify subclinical tophus deposits. Furthermore, tophus volume can be measured by DECT scans through an automated volume estimation procedure.

Dual energy CT in gout: a prospective validation study

Objective The authors prospectively determined: (1) the specificity and sensitivity of dual energy CT (DECT) for gout; and (2) the interobserver and intraobserver reproducibility for DECT urate volume measurements. Methods Forty crystal-proven gout patients (17 tophaceous) and 40 controls with other arthritic conditions prospectively underwent DECT scans of all peripheral joints using a gout protocol that color-codes the composition of tissues. A blinded radiologist identified urate deposition to calculate specificity and sensitivity of DECT for gout. Inter-rater volumetric reproducibility was determined by two independent radiologists on 40 index tophi from the 17 tophaceous gout patients using automated software. Results The mean age of the 40 gout patients was 62 years, the mean gout duration was 13 years and 87% had a history of urate-lowering therapy (ULT). The specificity and sensitivity of DECT for gout were 0.93 (95% CI, 0.80 to 0.98) and 0.78 (0.62 to 0.89), respectively. When the authors excluded three gout cases with unreadable or incomplete scans, the sensitivity was 0.84 (95% CI, 0.68 to 0.94). The urate volumes of 40 index tophi ranged from 0.06 cm3 to 18.74 cm3 with a mean of 2.45 cm3. Interobserver and intraobserver intraclass correlation coefficients for DECT volume measurements were 1.00 (95% CI, 1.00 to 1.00) and 1.00 (95% CI, 1.00 to 1.00) with corresponding bias estimates (SD) of 0.01 (0.00) cm3 and 0.01 (0.03) cm3. Conclusions These prospective data indicate high reproducibility of DECT urate volume measures. The specificity was high, but sensitivity was more moderate, potentially due to frequent ULT use in our patients.

Swine-Origin Influenza A (H1N1) Viral Infection: Radiographic and CT Findings

OBJECTIVE The objective of our study was to review the chest radiographic and CT findings in patients with swine-origin influenza A (H1N1) virus (S-OIV) infection. CONCLUSION The most common radiographic and CT findings in seven patients with S-OIV infection are unilateral or bilateral ground-glass opacities with or without associated focal or multifocal areas of consolidation. On MDCT, the ground-glass opacities and areas of consolidation had a predominant peribronchovascular and subpleural distribution, resembling organizing pneumonia.

Renal arterial resistive index response to intraabdominal hypertension in a porcine model.

Objective: The abdominal compartment syndrome is a potentially life‐threatening condition with frequent renal involvement. There are few if any means of inferring subclinical effects before organ dysfunction. Because intrarenal pressure correlates with renal sonographic indices in other renal diseases, the purpose of this study was to determine the relationship between increasing intraabdominal hypertension and renal vascular flow velocities in a porcine model using renal Doppler ultrasound. Design: Animal study. Setting: University research laboratory. Subjects: Eight anesthetized, mechanically ventilated, well‐hydrated, 30‐kg female Yorkshire pigs. Interventions: Intraabdominal hypertension was induced by instillation of warmed intraperitoneal saline through a midline laparoscopic port. Intraabdominal pressure (IAP) was continuously monitored directly from the peritoneum and indirectly from the bladder. IAP was varied from 0 to 50 mm Hg in increments of 5 mm Hg. At each IAP level, gray‐scale, color, and spectral Doppler renal arcuate artery ultrasound was obtained and resistive index (RI) and peak airway pressure calculated. Measurements and Main Results: Excellent agreement between direct and indirect IAP was found (bias, 0.032 mm Hg; 95% limits, −5.5 to 5.6 mm Hg). A linear relationship between RI and indirect IAP was observed and was defined by the regression equation: RI = 0.553 + 0.0104 × bladder pressure. There was a trend toward different RIs between left and right kidneys (p = .052) at the same IAP. RI varied in a linear fashion at low peak airway pressure and demonstrated an inflection point with steeper subsequent slope after peak airway pressure of 30 cm H2O. RI values rapidly returned to near baseline after abdominal decompression. Conclusions: In this model, the renal artery RI correlated strongly and linearly with the severity of intraabdominal hypertension, making renal Doppler ultrasound a potential noninvasive screening tool for the renal effects of intraabdominal hypertension. Further studies are warranted.

MR imaging features of bizarre parosteal osteochondromatous proliferation of bone (Nora's lesion)

The purpose of this study was to review the imaging findings of three patients with bizarre parosteal osteochrondromatous proliferation of bone (BPOP). The plain radiographs and MRI images of three patients with BPOP were obtained and retrospectively reviewed. In two cases, BPOP involved the feet. In one case BPOP involved the hand. In all three cases, plain radiographs showed a well-defined calcium containing mass adjacent to the cortical surface of the adjacent bone. The underlying bone appeared normal in all cases. On MRI, the lesion was of low signal intensity on T1 weighted sequences in all cases. On FSE T2 weighted and STIR sequences, the lesion was of high signal in all cases. The cortex, medullary cavity and adjacent soft tissues appeared normal in all cases. While BPOP is rare and often confused with a variety of both benign and malignant lesions, there are specific radiological findings that may help to distinguish BPOP from many of its mimickers.

The hand-held FAST: experience with hand-held trauma sonography in a level-I urban trauma center.

AIMS To describe the effectiveness of a portable hand-held ultrasound machine when used by clinicians in the early evaluation and resuscitation of trauma victims. METHODS The study was a prospective evaluation in a level-I urban trauma center. The focussed assessment with sonography for trauma is a specifically defined examination for free fluid known as the focused assessment with sonography for trauma (FAST) exam. Seventy-one patients had a hand-held FAST (HHFAST) examination performed with a Sonosite 180, 2.4 kg ultrasound machine. Sixty-seven examinations were immediately repeated with a Toshiba SSH 140A portable floor-based machine. This repeat scan (formal FAST or FFAST) was used as a comparison standard between the devices for study purposes. Four patients had a HHFAST only, all with positive result, two being taken for immediate laparotomy, and two having a follow-up computed tomographic (CT) scan. Patient follow-up from other imaging studies, operative intervention, and clinical outcomes were also compared to the performance of each device. RESULTS There were 58 victims of blunt, and 13 of penetrating abdominal trauma. One examination was indeterminate using both machines. The apparent HHFAST performance yielded; sensitivity, specificity, positive predictive value, negative predictable value, and accuracy (S, S, PPV, NPV, A) of 83, 100, 100, 98, 98%. Upon review, a CT scan finding and benign clinical course found the HHFAST diagnosis to be correct rather than the FFAST in one case. Considering the ultimate clinical course of the patients, yielded a (S, S, PPV, NPV, A) of 78, 100, 100, 97, and 97% for the HHFAST and 75, 98, 86, 97, and 96% for the FFAST. Statistically, there was no significant difference in the actual performance of the HHFAST compared to the FFAST in this clinical setting. DISCUSSION Hand-held portable sonography can simplify early and accurate performance of FAST exams in victims of abdominal trauma.

Sonographic Diagnosis of a Pneumothorax Inapparent on Plain Radiography: Confirmation by Computed Tomography

The focused assessment with sonography for trauma (FAST) consists of imaging the perihepatic, pelvic, perisplenic, and pericardial locations for the presence of free fluid.1,2 Although the pleural spaces may similarly be sonographically evaluated for pleural fluid using sonography,3 the FAST examination has not routinely been used to exclude pneumothorax. Traumatic pneumothorax is a frequent cause of preventable trauma death. Pneumothoraces are usually detected through clinical examination supplemented with plain chest radiographs. Most radiographs initially obtainable in severe blunt trauma settings are anteroposterior (AP) supine films because of concerns regarding spinal injury. In the supine patient, a pneumothorax is usually suggested by the presence of a deep sulcus sign, or the crisp definition of the pericardial silhouette.4 We describe the diagnosis of a small pneumothorax by thoracic ultrasound with computed tomographic (CT) confirmation in a patient after blunt trauma who had a nondiagnostic chest radiograph.

Imaging of Acute Small-Bowel Obstruction

OBJECTIVE The objective of this pictorial essay is to review the different imaging techniques used for diagnosing small-bowel obstruction. CONCLUSION Small-bowel obstruction is a common presentation, for which safe and effective management depends on a rapid and accurate diagnosis. Conventional radiographs remain the first line of imaging. CT is used increasingly more because it provides essential diagnostic information not apparent from radiographs. MRI may play a role in the future as technology improves and it becomes more readily available.

The Emerging Role of Cardiac Computed Tomography for the Assessment of Coronary Perfusion: A Systematic Review and Meta-analysis

BACKGROUND Computed tomography perfusion (CTP) is an emerging method which, coupled with the anatomical detail afforded by cardiac computed tomographic angiography (CCTA), may allow for determination of both structural and physiologic significance of coronary stenoses with a single imaging modality. This study was designed to execute a systematic review/meta-analysis to determine the sensitivity, specificity, positive predictive value (PPV), and negative predictive value (NPV) of CTP as compared with reference standards for detection of significant coronary artery stenoses and impaired perfusion. METHODS A systematic review identified 13 out of 4368 studies allowing a calculation of sensitivity, specificity, PPV, and NPV on a per patient or per vessel or per segment basis using radionuclide myocardial perfusion imaging (MPI), conventional coronary angiography (CCA), magnetic resonance perfusion imaging (MRPI), or fractional flow reserve (FFR) as the reference standard. Meta-analyses of results were carried out using random effects modelling. RESULTS Most studies used a maximal vasodilator stress protocol with adenosine, provided information mainly on a per vessel basis, and used myocardial perfusion imaging or CCA as the reference standard. Of the studies comparing combinations of both anatomical and functional imaging, the most rigourous standard was CCA/FFR. Compared with the latter, CCTA/CTP had sensitivity, specificity, PPV, and NPV of 81%, 93%, 87%, and 88%, respectively. CONCLUSIONS CTP shows promise as an adjunct to CCTA, potentially allowing determination of both structural and physiologic significance with a single imaging modality.