Role of advanced imaging techniques in the evaluation of oncological therapies in patients with colorectal liver metastases

In patients with colorectal liver metastasis(CRLMs)unsuitable for surgery,oncological treatments,such as chemotherapy and targeted agents,can be performed.Cross-sectional imaging[computed tomography(CT),magnetic resonance imaging(MRI),18-fluorodexoyglucose positron emission tomography with CT/MRI]evaluates the response of CRLMs to therapy,using post-treatment lesion shrinkage as a qualitative imaging parameter.This point is critical because the risk of toxicity induced by oncological treatments is not always balanced by an effective response to them.Consequently,there is a pressing need to define biomarkers that can predict treatment responses and estimate the likelihood of drug resistance in individual patients.Advanced quantitative imaging(diffusionweighted imaging,perfusion imaging,molecular imaging)allows the in vivo evaluation of specific biological tissue features described as quantitative parameters.Furthermore,radiomics can represent large amounts of numerical and statistical information buried inside cross-sectional images as quantitative parameters.As a result,parametric analysis(PA)translates the numerical data contained in the voxels of each image into quantitative parameters representative of peculiar neoplastic features such as perfusion,structural heterogeneity,cellularity,oxygenation,and glucose consumption.PA could be a potentially useful imaging marker for predicting CRLMs treatment response.This review describes the role of PA applied to cross-sectional imaging in predicting the response to oncological therapies in patients with CRLMs.

Radiomics and machine learning applications in rectal cancer:Current update and future perspectives

The high incidence of rectal cancer in both sexes makes it one of the most common tumors,with significant morbidity and mortality rates.To define the best treatment option and optimize patient outcome,several rectal cancer biological variables must be evaluated.Currently,medical imaging plays a crucial role in the characterization of this disease,and it often requires a multimodal approach.Magnetic resonance imaging is the first-choice imaging modality for local staging and restaging and can be used to detect high-risk prognostic factors.Computed tomography is widely adopted for the detection of distant metastases.However,conventional imaging has recognized limitations,and many rectal cancer characteristics remain assessable only after surgery and histopathology evaluation.There is a growing interest in artificial intelligence applications in medicine,and imaging is by no means an exception.The introduction of radiomics,which allows the extraction of quantitative features that reflect tumor heterogeneity,allows the mining of data in medical images and paved the way for the identification of potential new imaging biomarkers.To manage such a huge amount of data,the use of machine learning algorithms has been proposed.Indeed,without prior explicit programming,they can be employed to build prediction models to support clinical decision making.In this review,current applications and future perspectives of artificial intelligence in medical imaging of rectal cancer are presented,with an imaging modality-based approach and a keen eye on unsolved issues.The results are promising,but the road ahead for translation in clinical practice is rather long.

Non-invasive diagnostic imaging of colorectal liver metastases

Colorectal cancer is one of the few malignant tumors in which synchronous or metachronous liver metastases [colorectal liver metastases(CRLMs)] may be treated with surgery. It has been demonstrated that resection of CRLMs improves the long-term prognosis. On the other hand, patients with un-resectable CRLMs may benefit from chemotherapy alone or in addition to liverdirected therapies. The choice of the most appropriate therapeutic management of CRLMs depends mostly on the diagnostic imaging. Nowadays, multiple non-invasive imaging modalities are available and those have a pivotal role in the workup of patients with CRLMs. Although extensive research has been performed with regards to the diagnostic performance of ultrasonography, computed tomography, positron emission tomography and magnetic resonance for the detection of CRLMs, the optimal imaging strategies for staging and follow up are still to be established. This largely due to the progressive technological and pharmacological advances which are constantly improving the accuracy of each imaging modality. This review describes the non-invasive imaging approaches of CRLMs reporting the technical features, the clinical indications, the advantages and the potential limitations of each modality, as well as including some information on the development of new imaging modalities, the role of new contrast media and the feasibility of using parametric image analysis as diagnostic marker of presence of CRLMs.

Colorectal cancer and 18FDG-PET/CT:What about adding the T to the N parameter in loco-regional staging?

AIM:To evaluate whether FDG-positron emission tomography(PET)/computed tomography(CT)may be an accurate technique in the assessment of the T stage in patients with colorectal cancer.METHODS:Thirty four consecutive patients(20 men and 14 women;mean age:63 years)with a histologically proven diagnosis of colorectal adenocarcinoma and scheduled for surgery in our hospital were enrolled in this study.All patients underwent FDG-PET/CT preoperatively.The primary tumor site and extent were evaluated on PET/CT images.Colorectal wall invasion was analysed according to a modified T classification that considers only three stages(≤T2,T3,T4).Assessment of accuracy was carried out using 95%confidence intervals for T.RESULTS:Thirty five/37(94.6%)adenocarcinomas were identified and correctly located on PET/CT images.PET/CT correctly staged the T of 33/35 lesions identified showing an accuracy of 94.3%(95%CI:87%-100%).All T1,T3 and T4 lesions were correctly staged,while two T2 neoplasms were overstated as T3.CONCLUSION:Our data suggest that FDG-PET/CT may be an accurate modality for identifying primary tumor and defining its local extent in patients with colorectal cancer.

Colorectal cancer: Parametric evaluation of morphological,functional and molecular tomographic imaging

Colorectal cancer (CRC) represents one of the leading causes of tumor-related deaths worldwide. Among the various tools at physicians’ disposal for the diagnostic management of the disease, tomographic imaging (e.g., CT, MRI, and hybrid PET imaging) is considered essential. The qualitative and subjective evaluation of tomographic images is the main approach used to obtain valuable clinical information, although this strategy suffers from both intrinsic and operator-dependent limitations. More recently, advanced imaging techniques have been developed with the aim of overcoming these issues. Such techniques, such as diffusion-weighted MRI and perfusion imaging, were designed for the “in vivo” evaluation of specific biological tissue features in order to describe them in terms of quantitative parameters, which could answer questions difficult to address with conventional imaging alone (e.g., questions related to tissue characterization and prognosis). Furthermore, it has been observed that a large amount of numerical and statistical information is buried inside tomographic images, resulting in their invisibility during conventional assessment. This information can be extracted and represented in terms of quantitative parameters through different processes (e.g., texture analysis). Numerous researchers have focused their work on the significance of these quantitative imaging parameters for the management of CRC patients. In this review, we aimed to focus on evidence reported in the academic literature regarding the application of parametric imaging to the diagnosis, staging and prognosis of CRC while discussing future perspectives and present limitations. While the transition from purely anatomical to quantitative tomographic imaging appears achievable for CRC diagnostics, some essential milestones, such as scanning and analysis standardization and the definition of robust cut-off values, must be achieved before quantitative tomographic imaging can be incorporated into daily clinical practice.

Nuclear imaging to characterize adrenal tumors: Comparison with MRI

AIM:To describe the role of nuclear imaging modalities using nor-cholesterol,metaiodobenzylguanidine(MIBG)and fluorine-deoxy-glucose(FDG)in adrenal tumors for lesion characterization in comparison with magnetic resonance(MR).METHODS:Population was classified in group 1 consisting of 30 patients with non-hypersecreting unilateral adrenal masses,in group 2 consisting of 34 patients with hypersecreting(n=19)or non-hypersecreting(n=15)adrenal adenomas and in group 3 consisting of 18 patients with chromaffin-tissue tumors(CTT),of which 14 were pheochromocytomas while 4 were paragangliomas(n=4).All patients underwent MR and nuclear studies(nor-cholesterol,MIBG and FDG).Pathology samples(n=63)or follow-up data in adenomas(n=19)were used as standard of reference forimaging studies interpretation.RESULTS:In group 1,MR findings were not highly accurate for lesion characterization,while the results of nuclear scans showed abnormal nor-cholesterol,MIBG and FDG concentration in all cases of adenomas,pheos and malignant tumors,respectively.In group 2,no differences in MR parameters were found between hyperfunctioning and non-hyperfunctioning adenomas,while nor-cholesterol uptake was significantly higher in hyperfunctioning compared to non-hyperfunctioning lesions.In group 3,no differences in MR parameters were found between benign and malignant CCT,while MIBG uptake was significantly higher in malignant compared to benign tumors.CONCLUSION:On the basis of our findings,nuclear imaging modalities using specific target agents are able to better characterize adrenal tumors,compared with MR.In particular,radionuclide techniques are able to identify the nature of adrenal incidentalomas and to differentiate between hypersecreting and non-hypersecreting adenomas as well as between benign and malignant CTT.

Intestinal amyloidosis:Two cases with different patterns of clinical and imaging presentation

The involvement of the small bowel in systemic forms of amyloidosis may be diffuse or very rarely focal.Some cases of focal amyloidomas of the duodenum and jejunum without extraintestinal manifestations have been reported.The focal amyloidomas consisted of extensive amyloid infiltration of the entire intestinal wall thickness.Radiological barium studies,ultrasound and computed tomography(CT)patterns of diffuse small bowel amyloidosis have been described:the signs are non-specific and may include small-bowel dilatation,symmetric bowel wall thickening,mesenteric infiltration,and mesenteric adenopathy.No data are available about the positron emission tomography (PET)/CT and magnetic resonance imaging(MRI)patterns of intestinal amyloidosis.We report two cases of small bowel amyloidosis:the former characterized by focal deposition of amyloid proteins exclusively within blood vessel walls of the terminal ileum,the latter characterized by diffuse intestinal involvement observed on MRI and PET/CT studies.

Volvulus of the ascending colon in a non-rotated midgut:Plain film and MDCT findings

Colonic volvulus is a relatively uncommon cause of large bowel obstruction usually involving mobile,intraperitoneal,colonic segments.Congenital or acquired anatomic variation may be associated with an increased risk of colonic volvulus which can occasionally involve retro-peritoneal segments.We report a case of 54-year-old female who presented to our Institution to perform a plain abdominal film series for acute onset of cramping abdominal pain.Both the upright and supine films showed signs of acute colonic obstruction which was thought to be due to an internal hernia of the transverse colon into the lesser sac.The patient was therefore submitted to a multi-detector contrast-enhanced computed tomography(CT).CT findings were initially thought to be consistent with the presumed diagnosis of internal hernia but further evaluation and coronal reformatting clearly depicted the presence of a colonic volvulus possibly resulting from a retro-gastric colon.At surgery,a volvulus of the ascending colon was found and a right hemi-colectomy had to be performed.However,a non rotated midgut with a right-sided duodeno-jejunal flexure and a left sided colon was also found at laparotomy and over-looked in the pre-operative CT.Retrospective evaluation of CT images was therefore performed and a number of CT signs of intestinal malrotation could be identified.

Colonic perforation by a transmural and transvalvular migrated retained sponge:Multi-detector computed tomography findings

Transmural migrated retained sponges usually impact at the level of the ileo-cecal valve leading to a small bowel obstruction.Once passed through the ileo-cecal valve,a retained sponge can be propelled forward by peristaltic activity and eliminated with feces.We report the case of a 52-year-old female with a past surgical history and recurrent episodes of abdominal pain and constipation.On physical examination,a generalized resistance was observed with tenderness in the right flank.Contrast-enhanced multi-detector computed tomography findings were consistent with a perforated right colonic diverticulitis with several out-pouchings at the level of the ascending colon and evidence of free air in the right parieto-colic gutter along with an air-fluid collection within the mesentery.In addition,a ring-shaped hyperdense intraluminal material was also noted.At surgery,the ascending colon appeared irregularly thickened and folded with a focal wall interruption and a peri-visceral abscess at the level of the hepatic flexure,but no diverticula were found.A right hemi-colectomy was performed and on dissection of the surgical specimen a retained laparotomy sponge was found in the bowel lumen.