PET in abdominal pathology: advantages and limitations

Application of nanoparticles in cancer detection by Raman scattering based techniques

In vitro detection technique Raman spectroscopy (Rs), in one number times another Rs  based expert ways of art and so on, are useful instruments for cancer  discovery. top gave greater value to Raman spectroscopy  sers is a relatively new careful way for in vitro  and in vivo discovery that takes away bad points of simple Raman spectroscopy (Rs). Raman spectroscopy (RS) and in particular, multiple RS-based techniques are useful for cancer detection. Surface enhanced Raman spectroscopy (SERS) is a relatively new method for both in vitro and in vivo detection, which eliminates the drawbacks of simple RS. Using nanoparticles has elevated the sensitivity and specificity of SERS. SERS has the potential to increase sensitivity, specificity and spatial resolution in cancer detection, especially in cooperation with other diagnostic imaging tools such as magnetic resonance imaging (MRI) and PET-scan polyethylene terephthalate. Developing a hand held instrument for detecting cancer or other illnesses may also be feasible by using SERS. Frequently, novel nanoparticles are used in SERS. With a focus on nanoparticle utilization, we review the benefits of RS in cancer detection and related biomarkers. With a focus on nanoparticles utilizations, the benefits of RS in cancer detection and related biomarkers were reviewed. In addition, Raman applications to detect some of prevalent were discussed. Also more investigated cancers such as breast and colorectal cancer, multiple nanostructures and their possible special biomarkers, especially as SERS nano-tag have been reviewed. The main purpose of this article is introducing of most popular nanotechnological approaches in cancer detection by using Raman techniques. Moreover, have been caught up on detection and reviewed some of the most prevalent and also more investigated cancers such as breast, colorectal cancer, multiple intriguing nanostructures, especially as SERS nano-tag, special cancer biomarkers and related approaches. The main purpose of this article is to introduce the most popular nanotechnological approaches in cancer detection by using Raman techniques.

New and old tools for abdominal imaging in critically ill patients

Diagnostic imaging technology has advanced considerably during the past two decades. Different imaging techniques have been proposed for abdominal imaging in critically ill patients like plain radiography, sonography, computed tomography (CT), magnetic resonance and positron emission tomography. Sonography has been proven to be effective to detect free intra-peritoneal fluid and it is considered one of the primary diagnostic modalities for abdominal evaluation for trauma assessment. In our opinion sonography should replace other invasive techniques to rapidly triage blunt trauma patients with unstable vital signs and examine the peritoneal cavity as a site of major haemorrhage to expedite exploratory laparotomy. On the other hand, CT has become the imaging modality of choice in hemodynamically stable patients with multisystem blunt and penetrating trauma. New developments in the quantitative analysis of the CT images will improve our knowledge of pathophysiology, diagnostic and therapeutic management of abdominal pathologies in critically ill patients.

Improved attenuation correction via appropriate selection of respiratory-correlated PET data

PURPOSE

We propose a respiratory-correlated PET data processing method (called "BH-CT-based") based on breath-hold CT acquisition to reduce the smearing effect and improve the attenuation correction. The resulting images are compared with the ungated PET images acquired using a standard, free-breathing clinical protocol.

METHODS

The BH-CT-based method consisted of a list-mode acquisition with simultaneous respiratory signal recording. An additional breath-hold CT acquisition was also performed in order to define a tissue position from which PET events can be selected. A phantom study featured a 0.5-ml sphere (filled with 18F-fluorodeoxyglucose ((18)F-FDG) solution) pushed onto a rubber balloon (filled with (18)F-FDG solution and iodinated contrast agent). The feasibility of the BH-CT-based method was also assessed in two patients.

RESULTS

In the phantom study, the contrast-to-noise ratios (CNRs) were -1.6 for the Ungated volume and 5.1 for the BH-CT-based volume. For patients, CNRs were higher for BH-CT-based volumes than those for Ungated volumes (17.3 vs. 6.3 and 7.3 vs. 3.8, for patients 1 and 2, respectively). Bias-variance measurements were performed and yielded bias reduction of 40% with BH-CT-based.

CONCLUSION

The application of a BH-CT-based method decreases motion bias in PET images. This method resolves issues related to both PET-to-CT misregistration and erroneous attenuation correction and increases lesion detectability.

Staging of peritoneal carcinomatosis: enhanced CT vs. PET/CT

PURPOSE

To assess and compare the performance of CT and 18F-FDG-PET/CT in the evaluation of peritoneal carcinomatosis (PC).

METHOD AND MATERIALS

Thirty consecutive patients with PC and scheduled for a surgery underwent a CT of the abdomen and pelvis and a whole-body 18F-FDG PET/CT. The extent of PC was assessed precisely using the peritoneal cancer index combining the distribution of tumor throughout 11 abdominopelvic regions with a lesion size score. CT and PET/CT imaging results were compared in all patients with intraoperative findings using an interclass correlation test.

RESULTS

The presence of PC was correctly determined on CT and PET/CT in 23/28 and 16/28 patients, respectively. The extent of PC was understaged with CT and PET/CT in 27 patients and overstaged with CT and PET/CT in 1 and 2 patients, respectively. The interclass correlation was 0.53 (moderate) between CT and surgery and 0.12 (low) between PET/CT and surgery. The interclass correlation was higher for mucinous tumor (0.63) than for non-mucinous (0.16) on CT imaging whereas no difference was found in PET/CT.

CONCLUSION

The intraperitoneal assessment of the extent of carcinomatosis, necessary to assess prognosis and treatment planning, is not accurate enough with CT and PET/CT imaging.