Positron Range Corrections and Denoising Techniques for Gallium-68 PET Imaging: A Literature Review

Gallium-68 (68Ga) is characterized by relatively high positron energy compared to Fluorine-18 (18F), causing substantial image quality degradation. Furthermore, the presence of statistical noise can further degrade image quality. The aim of this literature review is to identify the recently developed positron range correction techniques for 68Ga, as well as noise reduction methods to enhance the image quality of low count 68Ga PET imaging. The search engines PubMed and Scopus were employed, and we limited our research to published results from January 2010 until 1 August 2022. Positron range correction was achieved by using either deblurring or deep learning approaches. The proposed techniques improved the image quality and, in some cases, achieved an image quality comparable to 18F PET. However, none of these techniques was validated in clinical studies. PET denoising for 68Ga-labeled radiotracers was reported using either reconstruction-based techniques or deep learning approaches. It was demonstrated that both approaches can substantially enhance the image quality by reducing the noise levels of low count 68Ga PET imaging. The combination of 68Ga-specific positron range correction techniques and image denoising approaches may enable the application of low-count, high-quality 68Ga PET imaging in a clinical setting.

Appraisal of the current guidelines for the management of diverticular disease using the Appraisal of Guidelines Research and Evaluation II (AGREE II) instrument

INTRODUCTION

Diverticular disease is one of the most frequent reasons for attending emergency departments and surgical causes of hospital admission. In the past decade, many surgical and gastroenterological societies have published guidelines for the management of diverticular disease. The aim of the present study was to appraise the methodological quality of these guidelines using the Appraisal of Guidelines Research and Evaluation II (AGREE II) tool.

METHODS

PubMed, Embase, Cochrane Library and Google Scholar databases were searched systematically. The methodological quality of the guidelines was appraised independently by five appraisers using the AGREE II instrument.

FINDINGS

A systematic search of the literature identified 12 guidelines. The median overall score of all guidelines was 68%. Across all guidelines, the highest score of 85% was demonstrated in the domain 'Scope and purpose'. The domains 'Clarity and presentation' and 'Editorial independence' both scored a median of 72%. The lowest scores were demonstrated in the domains 'Stakeholder involvement' and 'Applicability' at 46% and 40%, respectively. Overall, the National Institute for Health and Care Excellence (NICE) guidelines performed consistently well, scoring 100% in five of six domains; NICE was one of the few guidelines that specifically reported stakeholder involvement, scoring 97%. Generally, the domain of 'Stakeholder involvement' ranked poorly with seven of twelve guidelines scoring below 50%, with the worst score in this domain demonstrated by Danish guidelines at 25%.

CONCLUSION

Six of twelve guidelines (NICE, American Society of Colon & Rectal Surgeons (ASCRS), European Society of Coloproctology (ESCP), American Gastroenterological Association, German Society of Gastroenterology/German Society for General and Visceral Surgery (German), Netherlands Society of Surgery) scored above 70%. Only three, NICE, ASCRS and ESCP, scored above 75% and were voted unanimously by the appraisers for use as they are. Therefore, use of AGREE II may help improve the methodological quality of guidelines and their future updates.

Diversion, resection, or stenting as a bridge to surgery for acute neoplastic left-sided colonic obstruction: a systematic review and network meta-analysis of studies with curative intent

INTRODUCTION

The debate on the best surgical management strategy for acute malignant left-sided colonic obstruction is ongoing. Decompressing colostomy (DC) and stenting as a bridge to surgery (SBTS) are the currently proposed alternative approaches to emergency colectomy (EC). However, the results of a traditional meta-analysis were inconclusive. Therefore, a network meta-analysis (NMA) was conducted to compare the three approaches for acute left-sided colonic obstruction.

METHODS

A systematic literature search of Embase, PubMed, Google Scholar and the Cochrane library was performed. A traditional meta-analysis and subsequent NMA were conducted.

FINDINGS

A significantly greater number of primary anastomoses were performed in the DC cohort than in the EC and SBTS cohorts. The 90-day mortality rate was significantly lower in the DC cohort than in the EC and SBTS cohorts. Higher costs were associated with the SBTS cohort (by US$2,000) than with the EC cohort. The locoregional recurrence rate was higher for the SBTS cohort than for the EC cohort.

CONCLUSIONS

Evidence from the first NMA suggests there may be some clinical advantages associated with DC as an alternative approach to the EC and SBTS approaches for adequately selected patients with malignant large bowel obstruction.

Robotic vs laparoscopic total mesorectal excision for rectal cancers: has a paradigm change occurred? A systematic review by updated meta-analysis

AIM

The debate about the oncological adequacy, safety and efficiency of robotic vs laparoscopic total mesorectal excision for rectal cancers continues. Therefore, an updated, traditional and cumulative meta-analysis was performed with the aim of assessing the new evidence on this topic.

METHOD

A systematic search of the literature for data pertaining to the last 25 years was performed. Fixed- and random-effects models were used to cumulatively assess the accumulation of evidence over time.

RESULTS

Patients with a significantly higher body mass index (BMI), tumours located approximately 1 cm further distally and more patients undergoing neoadjuvant therapy were included in the robotic total mesorectal excision (RTME) cohort compared with those in the laparoscopic total mesorectal excision (LTME) cohort [RTME, mean difference (MD) = 0.22 (0.07, 0.36), P = 0.005; LTME, MD = -0.97 (-1.57, 0.36), P < 0.002; OR = 1.47 (1.11, 1.93), P = 0.006]. Significantly lower conversion rates to open surgery were observed in the RTME cohort than in the LTME cohort [OR = 0.33 (0.24, 0.46), P < 0.001]. Operative time in the LTME cohort was significantly reduced (by 50 min) compared with the RTME cohort. Subgroup analysis of the three randomized controlled trials (RCTs) challenged all the significant results of the main analysis and demonstrated nonsignificant differences between the RTME cohort and LTME cohort.

CONCLUSION

Although the RTME cohort included patients with a significantly higher BMI, more distal tumours and more patients undergoing neoadjuvant therapy, this cohort demonstrated lower conversion rates to open surgery when compared with the LTME cohort. However, subgroup analysis of the RCTs demonstrated nonsignificant differences between the two procedures.

Total extraperitoneal endoscopic hernioplasty (TEP) versus Lichtenstein hernioplasty: a systematic review by updated traditional and cumulative meta-analysis of randomised-controlled trials

Background–purpose

Totally extraperitoneal (TEP) endoscopic hernioplasty and Lichtenstein hernioplasty are the most commonly used approaches for inguinal hernia repair. However, current evidence on which is the preferred approach is inconclusive. This updated meta-analysis was conducted to track the accumulation of evidence over time.

Methods

Studies were identified by a systematic literature search of the EMBASE, PubMed, Cochrane Library, and Google Scholar databases. Fixed- and random-effects models were used to cumulatively assess the accumulation of evidence over time.

Results

The TEP cohort showed significantly higher rates of recurrences and vascular injuries compared to the Lichtenstein cohort; [Peto Odds ratio (OR) = 1.58 (1.22, 2.04), p = 0.005], [Peto OR = 2.49 (1.05, 5.88), p = 0.04], respectively. In contrast, haematoma formation rate, time to return to usual activities, and local paraesthesia were significantly lower in the TEP cohort compared to the Lichtenstein cohort; [Peto OR = 0.26 (0.16, 0.41), p ≤ 0.001], [mean difference = − 6.32 (− 8.17, − 4.48), p ≤ 0.001], [Peto OR = 0.26 (0.17, 0.40), p ≤ 0.001], respectively.

Conclusions

This study, which is based on randomised-controlled trials (RCTs) of high quality, showed significantly higher rates of recurrences and vascular injuries in the TEP cohort than in the Lichtenstein cohort. In contrast, rate of postoperative haematoma formation, local paraesthesia, and time to return to usual activities were significantly lower in the TEP cohort than in the Lichtenstein cohort. Future multicentre RCTs with strict adherence to the standards recommended in the Consolidated Standards of Reporting Trials guidelines will shed further light on the topic.

Electronic supplementary material

The online version of this article (10.1007/s10029-019-02049-w) contains supplementary material, which is available to authorized users.

Primary rectal malignant melanoma-case report

INTRODUCTION

Primary malignant melanoma that arises from the true anatomic rectal mucosa is extremely rare.

CASE REPORT

An endoscopic investigation of a 79-year-old woman with long history of tenesmus and rectal bleeding revealed posterior fleshy mass 4.5 cm from the anal verge. Biopsies demonstrated malignant melanoma. She underwent abdominoperineal resection and is doing well one year after the operation.

CONCLUSION

Owing to its rarity and histologic variability, misdiagnosis as lymphoma, carcinoma or sarcoma is common.