Contrast-enhanced multislice pneumo-CT-cystography in the evaluation of urinary bladder neoplasms

Nonionizing photoacoustic cystography with near-infrared absorbing gold nanostructures as optical-opaque tracers

AIM

The objectives of this study were to demonstrate nonionizing photoacoustic tomography (PAT) of bladders with near-infrared absorbing gold nanocages (GNCs) as an optical-turbid tracer and to investigate the fate of GNCs after photoacoustic imaging.

MATERIALS & METHODS

The rats' bladders were visualized using PAT after transurethral injection of 2-nM GNCs. The fate of GNCs in the bladders was investigated. Spectroscopic PAT was applied to identify GNC-filled bladders in vivo and study biodistribution ex vivo.

RESULTS

Rats' bladders filled with GNCs were successfully imaged using a PAT system. The photoacoustic amplitude was enhanced by approximately 2240%. Both in vivo and ex vivo PAT results reveal that no accumulation of GNCs in the bladder and kidney was observed, and were validated with inductively coupled plasma mass spectrometry.

CONCLUSION

The PAT with transurethral injection of GNCs provides two crucial safety features for clinical translation: no radiation exposure and no long-term heavy metal accumulation.

US detection of renal and ureteral calculi in patients with suspected renal colic

PURPOSE

The purpose of this study was to determine whether the color Doppler twinkling sign could be considered as an additional diagnostic feature of small renal lithiasis (_5mm).

METHODS

181 patients underwent CT scans performed for other pathologies; the images were also analyzed by a radiologists to identify the incidental presence of renal lithiasis equal to or smaller than 5 mm.These patients underwent an abdominal ultrasound examination, including grayscale analysis of the kidneys and color Doppler. Lithiasis were divided into three groups, on the basis of the diagnostic agreement provided by CT and gray scale results. Then, the twinkling sign sensitivity was assessed in the three groups.

RESULTS

The twinkling sign was positive in 177 out of 206 lithiasis (86 %) visible on CT, while the grayscale was absolutely positive in 98 out of 206 lithiasis (47.6%) and doubtful positive in 71 out of 206 lithiasis (31%).The twinkling sign was positive in 100% of absolutely positive and doubtful positive lithiasis on bmode, and in 8 out of 31 lithiasis not visible on b-mode.

CONCLUSIONS

In the diagnosis of small renal lithiasis, integrating gray-scale with color Doppler may be the most suitable procedure, because the color-Doppler twinkling sign is able to confirm the doubtful diagnosis of renal lithiasis and to detect some lithiasis that are not visible on b-mode.

Accuracy of ultrasonography in the diagnosis of acute calculous cholecystitis: review of the literature

Background

To evaluate the accuracy of ultrasonography in the diagnosis of acute calculous cholecystitis in comparison with other imaging modalities.

Methods

The authors performed a search of the Medline/ PubMed (National Library of Medicine, Bethesda, Maryland) for original research and review publications examining the accuracy of ultrasonography in the diagnosis of acute calculous cholecystitis. The search design utilized a single or combination of the following terms : (1) acute cholecystitis, (2) ultrasonography, (3) computed tomography, (4) magnetic resonance cholangiopancreatography and (5) cholescintigraphy. This review was restricted to human studies and to English-language literature. Four authors reviewed all the titles and subsequent the abstract of 198 articles that appeared appropriate. Other articles were recognized by reviewing the reference lists of significant papers. Finally, the full text of 31 papers was reviewed.

Results

Sonography is still used as the initial imaging technique for evaluating patients with suspected acute calculous cholecystitis because of its high sensitivity at the detection of GB stones, its real-time character, and its speed and portability. Cholescintigraphy still has the highest sensitivity and specificity in patients who are suspected of having acute cholecystitis. However, due to a combination of reasons including logistic drawbacks, broad imaging capability and clinician referral pattern the use of cholescintigraphy is limited in clinical practice. CT is particularly useful for evaluating the many complications of acute calculous cholecystitis. The lack of widespread availability of MRI and the relatively high cost prohibits its primary use in patients with acute calculous cholecystitis.

Conclusions

US is currently considered the preferred initial imaging technique for patients who are clinically suspected of having acute calculous cholecystitis.

Sources of error in emergency ultrasonography

BACKGROUND

To evaluate the common sources of diagnostic errors in emergency ultrasonography.

METHODS

The authors performed a Medline search using PubMed (National Library of Medicine, Bethesda, Maryland) for original research and review publications examining the common sources of errors in diagnosis with specific reference to emergency ultrasonography. The search design utilized different association of the following terms : (1) emergency ultrasonography, (2) error, (3) malpractice and (4) medical negligence. This review was restricted to human studies and to English-language literature. Four authors reviewed all the titles and subsequent the abstract of 171 articles that appeared appropriate. Other articles were recognized by reviewing the reference lists of significant papers. Finally, the full text of 48 selected articles was reviewed.

RESULTS

Several studies indicate that the etiology of error in emergency ultrasonography is multi-factorial. Common sources of error in emergency ultrasonography are: lack of attention to the clinical history and examination, lack of communication with the patient, lack of knowledge of the technical equipment, use of inappropriate probes, inadequate optimization of the images, failure of perception, lack of knowledge of the possible differential diagnoses, over-estimation of one's own skill, failure to suggest further ultrasound examinations or other imaging techniques.

CONCLUSIONS

To reduce errors in interpretation of ultrasonographic findings, the sonographer needs to be aware of the limitations of ultrasonography in the emergency setting, and the similarities in the appearances of various physiological and pathological processes. Adequate clinical informations are essential. Diagnostic errors should be considered not as signs of failure, but as learning opportunities.

Photoacoustic cystography

Conventional pediatric cystography, which is based on diagnostic X-ray using a radio-opaque dye, suffers from the use of harmful ionizing radiation. The risk of bladder cancers in children due to radiation exposure is more significant than many other cancers. Here we demonstrate the feasibility of nonionizing and noninvasive photoacoustic (PA) imaging of urinary bladders, referred to as photoacoustic cystography (PAC), using near-infrared (NIR) optical absorbents (i.e. methylene blue, plasmonic gold nanostructures, or single walled carbon nanotubes) as an optical-turbid tracer. We have successfully imaged a rat bladder filled with the optical absorbing agents using a dark-field confocal PAC system. After transurethral injection of the contrast agents, the rat's bladders were photoacoustically visualized by achieving significant PA signal enhancement. The accumulation was validated by spectroscopic PA imaging. Further, by using only a laser pulse energy of less than 1 mJ/cm(2) (1/20 of the safety limit), our current imaging system could map the methylene-blue-filled-rat-bladder at the depth of beyond 1 cm in biological tissues in vivo. Both in vivo and ex vivo PA imaging results validate that the contrast agents were naturally excreted via urination. Thus, there is no concern regarding long-term toxic agent accumulation, which will facilitate clinical translation.

Investigating the relationship between virtual cystoscopy image quality and CT slice thickness

OBJECTIVE

To investigate the effect of reconstruction slice thickness on image quality at CT virtual cystoscopy (VC).

METHODS

Pelvic CT examinations in bladder cancer patients were reconstructed at different slice thicknesses (0.6-5 mm) and intervals, and resulting VC images assessed. Quality indicators were ridging, holes, floaters and dimpling artefacts, tumour definition, and an overall score, ranked 1 (best) to 7 (worst). CT number and standard deviation (SD) for bladder contents and bladder wall were recorded. The mean SD was used as a measure of noise, and the contrast-to-noise ratio (CNR) was calculated as the CT number difference between them divided by the average image noise. The mean CNR across the three levels was used for analysis. Each qualitative image quality measure was compared with CT number, noise and CNR measurements.

RESULTS

Dimpling artefacts increased with thinner slice reconstruction and correlated with increased noise, often resulting in poor tumour definition. The best overall image quality score was seen for VC images reconstructed at 1.2 mm slice thickness, probably because of the competing effects of spatial resolution and CNR.

CONCLUSION

A slice thickness reconstruction <1.2 mm does not provide for better image quality at VC owing to the presence of increased noise.

Comparison of virtual cystoscopy and ultrasonography for bladder cancer detection: a meta-analysis

BACKGROUND AND PURPOSE

Bladder cancer is the most commonly diagnosed malignancy in patients presenting with haematuria. Early detection is crucial for improving patient prognosis. We therefore performed a meta-analysis to evaluate and compare the detection validity (sensitivity and specificity) of virtual cystoscopy (VC) and ultrasonography (US).

METHODS

We searched MEDLINE, EMBASE, PubMed and the Cochrane Library for studies evaluating diagnosis validity of VC and US between January 1966 and December 2009. Meta-analysis methods were used to pool sensitivity and specificity and to construct a summary receiver-operating characteristic (SROC) curve.

RESULTS

A total of 26 studies that included 3084 patients who fulfilled all of the inclusion criteria were considered for inclusion in the analysis. The pooled sensitivity for bladder cancer detection using CT virtual cystoscopy (CTVC), MR virtual cystoscopy (MRVC) and US was 0.939 (95% CI, 0.919-0.956), 0.908 (95% CI, 0.827-0.959) and 0.779 (95% CI, 0.744-0.812), respectively. The pooled specificity for bladder cancer detection using CTVC, MRVC and US was 0.981 (95% CI, 0.973-0.988), 0.948 (95% CI, 0.884-0.983) and 0.962 (95% CI, 0.953-0.969), respectively. The pooled diagnostic odd ratio (DOR) estimate for CTVC (604.22) were significantly higher than for MRVC (144.35, P<0.001) and US (72.472, P<0.001).

CONCLUSION

Our results showed that both CTVC and MRVC are better imaging methods for diagnosing bladder cancer than US. CTVC has higher diagnostic value (sensitivity, specificity and DOR) for the detection of bladder cancer than either MRCT or US.

MDCT Urography: Exploring a new paradigm for imaging of bladder cancer

OBJECTIVE

The purpose of this article is to review the epidemiology, staging, and treatment of bladder cancer; to discuss the role of MDCT urography for the evaluation of patients with known or suspected bladder cancer; and to address the role of MDCT urography in patients who require follow-up imaging after a diagnosis of bladder cancer has been made.

CONCLUSION

MDCT urography now has a large role in the evaluation of patients with known and suspected bladder cancer. However, its precise role has not been established. Because many bladder neoplasms will not be detected by MDCT urography and more research is needed to determine the optimal technique for diagnosing bladder cancer, we think that MDCT urography cannot replace cystoscopy at present.