PET/CT pattern analysis for surgical staple line recurrence in patients with colorectal cancer

Radiologic Imaging Modalities for Colorectal Cancer

BACKGROUND

Studies reported various diagnostic value of radiologic imaging modalities for diagnosis and management of colorectal cancer (CRC).

AIMS

To summary the diagnosis and management of CRC using computed tomography colonography (CTC), magnetic resonance colonography (MRC), and positron emission tomography (PET)/computed tomography (CT).

METHODS

Comprehensive literature searches were conducted in PubMed, EmBase, and the Cochrane library for studies published before April 2021. The diagnostic performance of CTC, MRC, and PET/CT for CRC was summarized.

RESULTS

A total of 54 studies (17 studies for CTC, 8 studies for MRC, and 29 studies for PET/CT) were selected for final analysis. The sensitivity and specificity for CTC ranged from 27 to 100%, 88 to 100%, respectively, and the pooled sensitivity and specificity for CTC were 0.97 (95% CI 0.88-0.99) and 0.99 (95% CI 0.99-1.00). The sensitivity and specificity for MRC ranged from 48 to 100%, 60 to 100%, respectively, and the pooled sensitivity and specificity for MRC were 0.98 (95% C: 0.77-1.00) and 0.94 (95% CI 0.84-0.98). The sensitivity and specificity for PET/CT ranged from 84 to 100%, 33 to 100%, respectively, and the pooled sensitivity and specificity for PET/CT were 0.94 (95% CI 0.92-0.96) and 0.94 (95% CI 0.90-0.97). The area under the receiver operating characteristic curve for CTC, MRC, and PET/CT was 1.00 (95% CI 0.99-1.00), 0.99 (95% CI 0.98-1.00), and 0.97 (0.95% CI 0.95-0.98), respectively.

CONCLUSIONS

This study suggested both CTC and MRC with relative higher diagnostic value for diagnosing CRC, while PET/CT with higher diagnostic value in detecting local recurrence for patients with CRC.

Differentiation between suture recurrence and suture granuloma after pulmonary resection for lung cancer by diffusion-weighted magnetic resonance imaging or FDG-PET / CT

There has been no publication which supports the usefulness of DWI differentiating for suture recurrence and suture granuloma after resection for lung cancer. We presented efficacy of DWI or FDG-PET/CT for an assessment of suture lesions after resection for lung cancer. Thirteen suture recurrences and 15 suture granulomas were examined. There were 24 adenocarcinomas and 4 squamous cell carcinomas, and 26 partial resections and 2 segmentectomies. The period of time (907±907 days) between surgery and suture recurrence was not significantly longer than that (546±547 days) between surgery and suture granuloma. Diffusion detectability scores (a 5-point scale) of suture recurrences was significantly higher than that of suture granulomas. The ADC value (1.35±0.24 × 10^-3mm²/sec) of suture recurrences was significantly lower than that (1.85±0.60 × 10^-3mm²/sec) of suture granulomas. The SUVmax (6.1 ± 5.0) of suture recurrences was not significantly higher than that (4.2 ± 2.5) of suture granulmas. The sensitivity of 85% (11/13) with DWI was not significantly higher than 69% (9/13) with FDG-PET/CT for suture recurrences. The specificity of 73% (11/15) with DWI was not significantly higher than the 60% (9/15) with FDG-PET/CT for suture granulomas. The accuracy of 79% (22/28) with DWI was not significantly higher than that of 64% (18/28) with FDG-PET/CT for suture recurrences and granulomas. DWI can differentiate suture granuloma from suture recurrence after resection of lung cancer. DWI is more useful than FDG-PET/CT for the differentiation between suture recurrence and suture granuloma after resection for lung cancer.

Pitfalls and value of organ specific approach in evaluating indeterminate lesions detected on CT in colorectal cancer by [F18] FDG PET/CT

Objective

The objective of this study is to evaluate the value of FDG PET/CT for different involved organs showing Indeterminate/ equivocal / suspicious lesions detected on IV contrasted CT during surveillance follow up for colorectal cancer.

Materials and methods

A total of 67 patients with colorectal cancer how are on regular surveillance follow up by IV contrasted CT scans revealing indeterminate lesions were studied. Subsequent FDG PET/CT evaluation was performed as a problem solving modality. PET/CT results were statistically characterized when compared to biopsy results or to follow/up results. Also Statistical parameters were calculated for each organ involved. The evaluation of all CT indeterminate lesions by FDG PET/CT showed overall sensitivity of 93%, Specificity of 81%, Negative predictive value of 94%, Positive predictive value 80% and accuracy of 87%. However in an organ specific approach the highest accuracy was for lymph nodes with results showing a 100% accuracy and the lowest accuracy was for local disease at a value of 80%. Probable explanations for the falsely characterized lesions resulting in the pitfalls seen and in the imperfect accuracy were provided.

Conclusion

Study shows that FDG PET/CT is an excellent tool in characterizing CT indeterminate lesions during surveillance of colorectal cancer, However different organs showed variable accuracy results with the highest accuracy for our study was for lymph node status (100%) and the lowest accuracy being for local disease at the original site of primary tumor (80%).

Colorectal cancer (CRC) monitoring by 6-monthly 18FDG-PET/CT: an open-label multicentre randomised trial

Background

[¹⁸F]2-fluoro-2-deoxy-d-glucose positron emission tomography/computed tomography (¹⁸FDG-PET/CT) has high sensitivity for detecting recurrences of colorectal cancer (CRC). Our objective was to determine whether adding routine 6-monthly ¹⁸FDG-PET/CT to our usual monitoring strategy improved patient outcomes and to assess the effect on costs.

Patients and methods

In this open-label multicentre trial, patients in remission of CRC (stage II perforated, stage III, or stage IV) after curative surgery were randomly assigned (1 : 1) to usual monitoring alone (3-monthly physical and tumour marker assays, 6-monthly liver ultrasound and chest radiograph, and 6-monthly whole-body computed tomography) or with 6-monthly ¹⁸FDG-PET/CT, for 3 years. A multidisciplinary committee reviewed each patient’s data every 3 months and classified the recurrence status as yes/no/doubtful. Recurrences were treated with curative surgery alone if feasible and with chemotherapy otherwise. The primary end point was treatment failure defined as unresectable recurrence or death. Relative risks were estimated, and survival was analysed using the Kaplan–Meier method, log-rank test, and Cox models. Direct costs were compared.

Results

Of the 239 enrolled patients, 120 were in the intervention arm and 119 in the control arm. The failure rate was 29.2% (31 unresectable recurrences and 4 deaths) in the intervention group and 23.7% (27 unresectable recurrences and 1 death) in the control group (relative risk = 1.23; 95% confidence interval, 0.80–1.88; P = 0.34). The multivariate analysis also showed no significant difference (hazards ratio, 1.33; 95% confidence interval, 0.8–2.19; P = 0.27). Median time to diagnosis of unresectable recurrence (months) was significantly shorter in the intervention group [7 (3–20) versus 14.3 (7.3–27), P = 0.016]. Mean cost/patient was higher in the intervention group (18 192 ± 27 679 € versus 11 131 ± 13  €, P < 0.033).

Conclusion

¹⁸FDG-PET/CT, when added every 6 months, increased costs without decreasing treatment failure rates in patients in remission of CRC. The control group had very close follow-up, and any additional improvement (if present) would be small and hard to detect.

ClinicalTrials.gov identifier

NCT00624260

Use of semiquantitative analysis in local recurrence of colorectal carcinoma with 18F-FDG PET/CT: A myth or a truth?

OBJECTIVE

Recurrence of colorectal cancer is mostly seen within the first 2 years after surgery. The most frequent site of recurrence is the postsurgical areas and its surroundings. The purpose of this study was to evaluate the usefulness of semiquantitative analysis of ¹⁸Fluorine fluorodeoxyglucose (FDG) positron emission tomography/computed tomography (PET/CT) in determining recurrence of colorectal carcinoma in the operation site.

MATERIAL AND METHODS

Files of 35 patients with colorectal carcinoma (25 men, 10 women, mean age: 59.25±2.82 years, range: 27-80 years) who were treated with surgery and underwent FDG PET/CT scanning for restaging of colorectal carcinoma and showing increased FDG uptake in the postsurgical area, were retrospectively analysed. Besides calculating SUVmax of the areas showing FDG uptake, SUVmax of physiological colonic activity was also obtained and SUVmax of lesion/SUVmax of colonic wall (RSUVmax), was calculated. Characteristics of FDG uptake were classified according to histological analysis or clinical and imaging follow-up.

RESULTS

In 17 of 35 patients (49%) the standard of reference for the final diagnosis was histologic analysis and in 18 (51%), final diagnosis was based on imaging and clinical follow-up. In 15 of 35 patients (43%) the etiology of increased FDG uptake was recurrence and in 20 (57%), FDG accumulation was observed due to benign etiology. The difference between the mean of the results of SUVmax in patients with recurrent disease and with no evidence of recurrence was statistically significant (P=.030). For SUVmax, a cut-off value for recurrence was calculated as 9.51 with a sensitivity of 80% and a specificity of 70%. In terms of RSUVmax results, a statistically significant difference was also observed between mean values in patients with recurrent disease and in those without (P=.002). ROC analysis demonstrated that the best predictive value of RSUVmax for recurrence was 1.75 with a sensitivity of 67% and specificity of 95%.

CONCLUSIONS

Semiquantitative analysis of FDG PET/CT may be used in detecting recurrent disease of patients with colorectal carcinoma. Eliminating interfering physiological colonic activity in analysis may have an incremental effect on the success of this technique, by means of increasing the specificity.

A Spectrum of Entities That May Mimic Abdominopelvic Abscesses Requiring Image-guided Drainage

A variety of entities may mimic drainable abscesses. This can lead to misdiagnosis of these entities, unnecessary percutaneous placement of a pigtail drainage catheter, other complications, and delay in appropriate treatment of the patient. Types of entities that may mimic drainable abscesses include neoplasms (lymphoma, gallbladder cancer, gastrointestinal stromal tumor, ovarian cancer, mesenteric fibromatosis, ruptured mature cystic teratoma, recurrent malignancy in a surgical bed), ischemia/infarction (liquefactive infarction of the spleen, infarcted splenule), diverticula (calyceal, Meckel, and giant colonic diverticula), and congenital variants (obstructed duplicated collecting system). Postoperative changes, including expected anatomy after urinary diversion or Roux-en-Y gastric bypass and small bowel resection, may also pose a diagnostic challenge. Nonpyogenic infections (Mycobacterium tuberculosis, Mycobacterium avium complex, echinococcal cysts) and inflammatory conditions such as xanthogranulomatous pyelonephritis and gossypiboma could also be misinterpreted as drainable fluid collections. Appropriate recognition of these entities is essential for optimal patient care. This article exposes radiologists to a variety of entities for which percutaneous drainage may be requested, but is not indicated, and highlights important imaging findings associated with these entities to facilitate greater diagnostic accuracy and treatment in their practice. ^©RSNA, 2018.

Prospective Trial Evaluating the Surgical Anastomosis at One-Year Colorectal Cancer Surveillance: CT Colonography Versus Optical Colonoscopy and Implications for Patient Care

OBJECTIVE

The aim of this study was to compare the accuracy of CT colonography versus optical colonoscopy for neoplastic involvement at the surgical anastomosis 1 year after curative-intent colorectal cancer resection.

DESIGN, SETTING, PATIENTS, AND INTERVENTIONS

Two hundred one patients (mean age, 58.6 years; 117 men, 84 women) underwent same-day contrast-enhanced CT colonography and colonoscopy approximately 1 year (mean, 12.1 months; median, 11.9 months) after colorectal cancer resection as part of a prospective, multicenter trial. All patients enrolled were without clinical evidence of disease and considered low risk for recurrence (stage I-III).

MAIN OUTCOME MEASURES

Suspected neoplastic lesions within 5 cm of the colonic anastomosis were recorded at CT colonography, with subsequent colonoscopy performed for the same, with segmental unblinding of colonography findings. Anastomotic region biopsy or polypectomy was performed at the endoscopist's discretion.

RESULTS

None of the 201 patients had intraluminal anastomotic cancer recurrence or advanced neoplasia (or metachronous cancers). CT colonography detected extramural perianastomotic recurrence in 2 patients (1.0%); neither was detected at colonoscopy. Only 2 patients (1.0%; 2/201) were called positive at CT colonography for intraluminal anastomotic nondiminutive lesions (7- to 8-mm polyps), which were confirmed at colonoscopy but nonneoplastic at histopathology. At optical colonoscopy, the anastomosis was deemed abnormal and/or biopsied in 10.0% (20/201), yielding only 1 nondiminutive benign neoplasm (7-mm tubular adenoma).

LIMITATIONS

The lack of luminal cancer recurrence in our lower-risk cohort precludes assessment of sensitivity for detection, rendering the study underpowered in this regard. Potential cost savings of combined CT/CT colonography over the standard CT/colonoscopy approach were not assessed.

CONCLUSIONS

Relevant intraluminal anastomotic pathology appears to be very uncommon 1 year after colorectal cancer resection in lower-risk cohorts. Unlike colonoscopy, diagnostic contrast-enhanced CT colonography effectively evaluates both the intra- and extraluminal aspects of the anastomosis. See Video Abstract at http://links.lww.com/DCR/A471.

FDG-PET/CT in the Postoperative Period: Utility, Expected Findings, Complications, and Pitfalls

FDG-PET/CT as a modality is increasingly used for detection of recurrence and for restaging in patients with clinical suspicion of malignancy, as well as in patients with elevated tumor markers. However, there are many pitfalls in the interpretation of these scans when the studies are performed after some treatment. Some of these are attributed to normal physiological distribution and are compounded when there are inflammatory changes occurring after surgery. The body's inherent response to the surgical insult results in this inflammation. In addition, there are also complications that can happen following surgery, causing increased FDG uptake. Despite various fallacies, FDG-PET/CT provides valuable information in evaluation of residual and recurrent malignant disease. In this article, we aim to describe some of these postsurgical changes secondary to inflammation, common surgical complications, and finally, the utility of FDG-PET/CT in these patients to detect recurrent disease, even in the background of postsurgical changes.

Visual and quantitative comparison of (18)F-fluorodeoxyglucose PET/CT findings in the detection of pelvic tumor recurrence in colorectal cancer

OBJECTIVE

This study aimed to visually and quantitatively compare (18)F-fluorodeoxyglucose positron emission tomography/computed tomography (PET/CT) imaging in determining postoperative pelvic recurrence in colorectal cancer (CRC).

MATERIALS AND METHODS

This retrospective analysis focused on 96 patients (age: mean 62.6 ± 10.5) with surgically resected CRC (time interval after surgery: 19.2 ± 20.4 months). The standard of reference was histopathologic confirmation (n = 27) or imaging follow-up (n = 69). For visual analysis, three independent nuclear physicians interpreted the PET/CT findings. For the quantitative analysis, the normalized standardized uptake values (nSUVs: nSUVmax, nSUVpeak, nSUVmean) were calculated by applying the mean SUV of a normal liver. We evaluated the areas under the receiver operating characteristic curves (AUCs) for all the quantitative parameters.

RESULTS

Of the 96 patients, 49 showed pelvic recurrence and 47 revealed no tumor recurrence. Sensitivity and specificity were 85.7 and 80.9 %, respectively, for visual analysis, and 65.3 and 83.0 %, respectively, for quantitative analysis. The AUC (0.766, CI: 0.668-0.846) of nSUVmax was largest comparing nSUVpeak and nSUVmean values, without significant difference (p value >0.316). Sensitivity of lesion detection was superior in visual analysis (p value = 0.02), but specificity was not significantly different (p = 0.80). After inclusive and exclusive combinations, sensitivity and specificity were slightly increased to 89.8 % (p = 0.54) and 91.5 % (p = 0.14), respectively.

CONCLUSIONS

Visual interpretation was superior to quantitative analysis in pelvic tumor recurrence in CRC. Though it was possible to improve diagnostic performance through combinatory analysis, the effect was not statistically significant.

FDG PET/CT in the management of colorectal and anal cancers

OBJECTIVE

CT remains the imaging modality of choice in the diagnosis of colorectal cancer (CRC) and anal cancer. However, advances in imaging have expanded the role of MRI and PET/CT. This article focuses on the evolving role of FDG PET/CT in the diagnosis, radiation therapy planning, therapy assessment, and posttherapy monitoring of CRC and anal cancer.

CONCLUSION

FDG PET/CT is a valuable imaging modality that impacts the clinical management of patients with CRC and those with anal cancer.

The rim sign: FDG-PET/CT pattern of pulmonary infarction

Objective

We aimed to describe a pattern of rim uptake observed in lung infarction on FDG-PET/CT, called the “rim sign.” It was defined as a continuous slight FDG uptake along the border of a subpleural consolidation without uptake within the consolidation.

Methods

We retrospectively reviewed the FDG-PET/CT studies of 400 patients referred for thoracic oncological workup from November 2010 to July 2011. The rim sign was observed in six patients who had confirmed pulmonary infarction (PI) on MDCT showing acute pulmonary embolism (n = 4) or tumoral arterial obstruction (n = 2).

Results

Eight PIs in the six patients exhibited the rim sign with slight uptake (median SUV_max: 3.6, 2.2–6.8) and median size of 48.5 mm (30–74). On MDCT, central lucencies, triangular shape and vessel sign were observed in 5/8, 4/8 and 1/8 cases, respectively. Two out of the eight PIs exhibited only the rim sign and none the suggestive MDCT sign.

Conclusion

The rim sign is easily recognisable at FDG-PET/CT and is strongly suggestive of PI. This pattern can be observed even in the absence of suggestive findings on MDCT. Recognition of this sign should prompt investigations for pulmonary embolism.

Main Messages

• The rim sign is a slight FDG uptake around an area of subpleural consolidation

• The rim sign is strongly suggestive of pulmonary infarction

• Recognition of the rim sign should prompt investigations for pulmonary embolism

Colorectal cancer - patterns of locoregional recurrence and distant metastases as demonstrated by FDG PET / CT

Colorectal cancer (CRC) can recur locoregionally or at distant sites. Timely diagnosis of recurrence is of paramount importance, as radical treatment of the localized disease can prolong survival. Fluorodeoxyglucose positron emission tomography / computed tomography (PET / CT) is routinely used in restaging and surveillance of colorectal cancer, as it can demonstrate recurrent disease with good accuracy. This article illustrates the spectrum of standard as well as unusual patterns of local recurrence and distant metastases of colorectal cancer.