Pre-operative localisation of axillary lymph nodes using radiofrequency identification (RFID) tags: a feasibility assessment in 75 cases

AIM

To evaluate the safety and feasibility of using radiofrequency identification (RFID) tags for the localisation of axillary nodes prior to targeted excision in a National Health Service (NHS) breast unit.

MATERIALS AND METHODS

Retrospective data collection was carried out to analyse the first 75 cases of RFID-targeted axillary nodes inserted between 12 June 2019 and 27 October 2022, during which an overall total of 1,296 breast and axillary tags were deployed in 1,120 patients.

RESULTS

Of the 75 axillary tags, 70 (93%) had a primary breast cancer and five (7%) had no known breast cancer but had an abnormal node targeted for diagnostic excision. Of the 70 with breast cancer, 20 (29%) underwent neoadjuvant chemotherapy (NAC) including one neoadjuvant endocrine therapy. Localisations were performed an average of 11 days before surgery (median 6, range 1-95; n=75). Patients undergoing NAC had their tags inserted after completing treatment due to the artefact caused by the tags on magnetic resonance imaging (MRI). Tag deployment had a 100% success rate, with 62 tags (83%) lying within the node and 13 tags (17%) lying directly adjacent to the node, either in direct contact (nine of 13), or a maximum of 8 mm from the target (four of 13). All tags and their respective nodes were excised successfully at surgery with no significant complications. There were four cases of tag dislodgement during excision, but overall, this did not compromise retrieval of the tag or the node.

CONCLUSIONS

The use of RFID tags for the preoperative localisation of axillary nodes is safe and feasible.

A national survey investigating the impact of the COVID-19 pandemic on core and higher breast radiology training in the UK

AIM

To investigate the impact of the COVID-19 pandemic on core and higher breast radiology training in the UK from the perspective of trainees and new consultants.

MATERIALS AND METHODS

A survey comprising 25 questions was distributed to UK radiology trainees via the regional Junior Radiologists Forum representatives under the auspices of the British Society of Breast Radiology (BSBR).

RESULTS

Sixty-nine eligible responses were received representing all UK training regions. Fifty-five per cent of respondents completing either a core or higher breast rotation felt that the pandemic had a negative effect on their breast training. There was an overall reduction in exposure to the key breast imaging methods when rotations took place during the pandemic. Completing a core breast rotation during the pandemic was less likely to attract trainees to higher breast training. Three out of four breast radiology consultants in their first year after receiving their Certificate of Completion of Training (CCT) felt the pandemic reduced their preparedness for becoming consultants. Positive outcomes included the increased use of online educational resources and remote multidisciplinary meetings.

CONCLUSIONS

As well as having a negative impact on breast radiology training overall, the pandemic has had a detrimental effect on attracting trainees to breast radiology as a future career. It is of key importance that trainees have a positive core breast rotation as this experience appears central to many trainees' decisions to pursue higher breast training. Increased use of online learning resources has also been positively received and is a valuable approach to learning that can be maintained in the longer term.

Use of Hologic LOCalizer radiofrequency identification (RFID) tags to localise impalpable breast lesions and axillary nodes: experience of the first 150 cases in a UK breast unit

AIM

To report the outcome of 150 patients using the Hologic LOCalizer RFID (radiofrequency identification) tag system, including the first reported use of RFID tags in the axilla.

MATERIALS AND METHODS

Data were collected prospectively from the first tag insertion (12 June 2019) until 150 consecutive patients had undergone surgery (excision date 9 January 2020).

RESULTS

A total of 177 tags were targeted to 177 malignant lesions in 150 women. Tags were inserted an average of 7.8 days before surgery (range 0-71 days). One hundred and twenty-six tags were targeted to a single lesion in one breast only; the remainder of tags were targeted to multiple lesions in one or both breasts, as well as to axillary lymph nodes. In addition, two cases involved the use of two tags to bracket microcalcification. All except three tags were satisfactorily deployed at their initial intended target. The majority of target lesions were masses (n=142, mean size 13.8 mm), with a range of other targets including post-vacuum-assisted biopsy cavities, marker clips post-neoadjuvant chemotherapy, architectural distortions, and clipped metastatic lymph nodes. All tags were successfully retrieved at surgical excision. Re-excision rate was 8.7%. There were no tag-specific surgical complications.

CONCLUSIONS

The RFID tag system demonstrates many advantages over guidewires, and is effective at targeting axillary lymph nodes and multiple sites within the same breast.

A national survey exploring UK trainees' perceptions, core training experience, and decisions to pursue advanced training in breast radiology

AIM

To investigate UK radiology trainees' perceptions of breast radiology and the factors that influenced their decision whether or not to choose breast radiology as an area of special interest.

MATERIALS & METHODS

An online survey was compiled and distributed to all UK specialty trainees in clinical radiology via the Royal College of Radiologists Junior Radiologists' Forum (JRF) regional representatives.

RESULTS

There were 275 respondents, representing 22% of all UK radiology trainees. Responses were received from all regions. A significant factor identified in influencing whether or not trainees decide to pursue advanced training in breast radiology is the timing and quality of their initial core training experience. Specific positive aspects of breast radiology that were repeatedly identified included the high level of patient contact and frequent use of interventional procedures. Recurring negative aspects of breast radiology included isolation from general radiology and finding the subject matter boring.

CONCLUSION

Breast radiology faces a significant workforce shortfall that is predicted to worsen in the coming years. There has never been a greater need to recruit specialty trainees into this field, and action is urgently needed to help ensure the sustainability of breast services and drive further improvements to patient care. The findings from this survey should be regarded as a challenge to all breast radiologists to engage with trainees from an early stage in their training and to enthuse them with the many positive aspects of a career in breast radiology.

Tiered approaches to chromatographic bioanalytical method performance evaluation: recommendation for best practices and harmonization from the Global Bioanalysis Consortium harmonization team

The A2 harmonization team, a part of the Global Bioanalysis Consortium (GBC), focused on defining possible tiers of chromatographic-based bioanalytical method performance. The need for developing bioanalytical methods suitable for the intended use is not a new proposal and is already referenced in regulatory guidance language. However, the practical implementation of approaches that differ from the well-established full validation requirements has proven challenging. Advances in technologies, the need to progress drug development more efficiently, and emerging new drug compound classes support the use of categorized tiers of bioanalytical methods. This paper incorporated the input from an international team of experienced bioanalysts to surmise the advantages and the challenges of tiered approaches and to provide recommendations on paths forward.

The Contribution of Organic Anion Transporters OAT1 and OAT3 to the Renal Uptake of Rosuvastatin

Rosuvastatin is a potent inhibitor of 3-hydroxy-3-methylglutaryl-CoA reductase and has been shown to be highly effective in reducing low-density lipoprotein cholesterol. Clinical trials have demonstrated that renal excretion and, in particular, tubular secretion, plays a role in rosuvastatin clearance. The aim of this study was to determine the involvement of the basolateral organic anion transporters, OAT1 and OAT3, in the renal uptake of rosuvastatin. Expression of human (h) OAT3 in Xenopus oocytes significantly increased the uptake of rosuvastatin above control levels (K(m) = 7.4 microM). In contrast hOAT1 did not mediate rosuvastatin uptake. Furthermore, hOAT3-mediated estrone-3-sulfate uptake could be inhibited, with a rank order of potency, by atorvastatin, rosuvastatin, simvastatin, and pravastatin, whereas hOAT1-mediated PAH uptake was only significantly inhibited by simvastatin. To estimate the contribution of hOAT3 to the overall renal uptake of rosuvastatin, a series of experiments were conducted using rat kidney slices. Rosuvastatin uptake in rat renal slices was abolished in the presence of the rat (r) Oat3-specific inhibitor benzylpenicillin, suggesting that rOat3 is responsible for the majority of rosuvastatin uptake across the basolateral membrane in rat kidney. From these findings, we can suggest that hOAT3 contributes to the renal uptake of rosuvastatin in humans.

Genomic variation in Streptococcus mutans: deletions affecting the multiple pathways of β-glucoside metabolism

The genome of Streptococcus mutans UA159 contains two phospho-beta-glucosidase genes, bglA and celA, which occur in operon-like arrangements along with genes for components of phosphotransferase transport systems and a third phospho-beta-glucosidase encoded by the arb gene, which does not have its own associated transport system but relies on uptake by the bgl or cel systems. Targeted inactivation of each of the phospho-beta-glucosidase genes revealed that bglA is involved in aesculin hydrolysis, celA is essential for utilisation of cellobiose, amygdalin, gentobiose and salicin, and arb is required for utilisation of arbutin. Inactivation of genes for the phosphotransferase systems revealed an overlap of specificity for transport of beta-glucosides and also indicated that further, unidentified transport systems exist. The cel and arb genes are subject to catabolite repression by glucose, but the regM gene is not essential for catabolite repression. Screening a collection of isolates of S. mutans revealed strains with deletions affecting the msm, bgl and/or cel operons. The phenotypes of these strains could largely be explained on the basis of the results obtained from the knockout mutants of S. mutans UA159 but also indicated the existence of other pathways apparently absent from UA159. The extensive genetic and phenotypic variation found in beta-glucoside metabolism indicates that there may be extensive heterogeneity in the species.

Human intestinal cell monolayers are preferentially sensitive to disruption of barrier function from basolateral exposure to cholic acid: correlation with membrane transport and transepithelial secretion

Unconjugated bile acids such as cholic acid cause diarrhoea, mucosal irritation and toxicity. We sought to define the mechanism of cholate permeation across intestinal mucosal cells to understand how cellular exposure and accumulation are deleterious to mucosal function. Human intestinal Caco-2 and T84 cell monolayers were prepared by high-density seeding and cultured for >14 days on permeable culture supports. Cholate transport and cellular accumulation were determined using [3H]cholic acid. Epithelial barrier function was assessed by measuring transepithelial electrical resistance (Rt) and [14C]mannitol fluxes. Exposure of Caco-2 epithelia to serosal cholate caused a dose- and time-dependent disruption of barrier function. Apical exposure was without disruptive effect. Similar responses were observed for T84 epithelia. Cholate was preferentially accumulated across the basolateral surfaces in both Caco-2 and T84 cells, but was subject to active transepithelial secretion in Caco-2 monolayers only. Net secretion was substantially reduced by ATP depletion, showed saturation kinetics, and was subject to competitive inhibition by other bile acids. Cholate secretion was also sensitive to inhibition by the leukotriene antagonist MK-571 but not by digoxin, suggesting that MRP2, not MDR1, was responsible. RT-PCR and Western blotting confirmed MRP2 expression in Caco-2 epithelia but indicated its apparent absence from T84 cells.

A four-column parallel chromatography system for isocratic or gradient LC/MS analyses

A novel approach to parallel liquid chromatography/ tandem mass spectrometry (LC/MS/MS) analyses for pharmacokinetic assays and for similar quantitative applications is presented. Modest modifications render a conventional LC/MS system capable of analyzing samples in parallel. These modifications involve the simple incorporation of three valves and four LC columns into a conventional system composed of one binary LC pumping system, one autosampler, and one mass spectrometer. An increase in sample throughput is achieved by staggering injections onto the four columns, allowing the mass spectrometer to continuously analyze the chromatographic window of interest Using this approach, the optimized run time is slightly greater than the sum of the widths of the desired peaks. This parallel chromatography unit can operate under both gradient and isocratic LC conditions. To demonstrate the utility of the system, atorvastatin, five of its metabolites, and their deuterated internal standards (IS) were analyzed using gradient elution chromatography conditions. The results from a prestudy assay evaluation (PSAE) tray of standards and quality control (QC) samples from extracted spiked human plasma are presented. The relative standard deviation and the accuracy of the QC samples did not exceed 8.1% and 9.6%, respectively, which is well within the acceptance criteria of the pharmaceutical industry. For this particular analysis, the parallel chromatography system decreased the overall run time from 4.5 to 1.65 min and, therefore, increased the overall throughput by a factor of 2.7 in comparison to a conventional LC/MS/MS analytical method.

Quantitative liquid chromatographic-tandem mass spectrometric determination of reserpine in FVB/N mouse plasma using a "chelating" agent (disodium EDTA) for releasing protein-bound analytes during 96-well liquid-liquid extraction

A sensitive, specific, accurate and reproducible analytical method employing a divalent cation chelating agent (disodium EDTA) for sample treatment was developed to quantitate reserpine in FVB/N mouse plasma. Samples pretreated with 40 microl of 2% disodium EDTA in water were extracted by a semi-automated 96-well liquid-liquid extraction (LLE) procedure to isolate reserpine and a structural analog internal standard (I.S.), rescinnamine, from mouse plasma. The extracts were analyzed by turbo ionspray liquid chromatography-tandem mass spectrometry (LC-MS-MS) in the positive ion mode. Sample preparation time for conventional LLE was dramatically reduced by the semi-automated 96-well LLE approach. The assay demonstrated a lower limit of quantitation of 0.02 ng/ml using 0.1-ml plasma sample aliquots. The calibration curves were linear from 0.02 to 10 ng/ml for reserpine. The intra- and inter-assay precision of quality control (QC) samples ranged from 1.75 to 10.9% for reserpine. The intra- and inter-assay accuracy of QC samples ranged from -8.17 to 8.61%. Reserpine and the I.S. were found to be highly bound to FVB/N mouse plasma protein. This is the first report of disodium EDTA employed as a special protein-bound release agent to recover protein-bound analytes from plasma. These matrix effects and the effects of pH in the HPLC mobile phase on the sensitivities of LC-MS-MS are discussed in this paper.

Analysis of clenbuterol in human plasma using liquid chromatography/atmospheric-pressure chemical-ionization mass spectrometry

Clenbuterol is a beta-agonist drug used illegally as a growth stimulant in meat-producing animals and human athletes. The analysis of clenbuterol in spiked human plasma was performed using on-line liquid chromatography/atmospheric-pressure chemical-ionization mass spectrometry (LC/APCI-MS) using a conventional bore LC column (flow rate = 1.0 mL/min). At low sampling cone voltages, the mass spectrum was predominantly the [M+H]+ ion but diagnostic fragment ions were formed upon incremental increases in sampling cone voltage. The detection limit (signal-to-noise ratio of 3) using selected-ion monitoring of the [M+H]+ ion was 0.1 ng on-column (10 ppb). This is a 50-fold better sensitivity of detection than that previously reported for an on-line thermospray LC/MS method. The extraction procedures were not optimized for maximum sensitivity and the lack of interferences suggests that much lower detection limits for clenbuterol in plasma are attainable.

Identification of urinary acylcarnitines using gas chromatography-mass spectrometry: preliminary clinical applications

Many disorders of organic acid metabolism are associated with abnormalities in the levels of acylcarnitines excreted in urine. Profiling of urinary acylcarnitines allows diagnosis and characterisation of many acidurias and acidemias, monitoring dietary treatment of such patients, and elucidation of the metabolism of some exogenous acidic compounds. Urine (ca. 0.5 ml) was subjected to a simple work-up by ion-exchange chromatography, and the isolated acylcarnitines were derivatized by cyclization in 35 min to give volatile lactones that are compatible with gas chromatography-mass spectrometry using electron or chemical ionization. The feasibility of this new and affordable procedure has been confirmed by identifying urinary acylcarnitines in cases of medium-chain acyl-coenzyme A dehydrogenase deficiency, propionic acidemia and isovaleric acidemia.

Simple and unambiguous method for identifying urinary acylcarnitines using gas chromatography--mass spectrometry

Several inherited metabolic disorders, particularly the organic acidurias and acidemias, are often characterised by excretion of acylcarnitines, especially octanoylcarnitine, in the urine. Clinical investigation of such serious disorders ideally requires a rapid, simple and selective method for determining acylcarnitines in urine. Initial results are given here of a method that may approach this ideal. The procedure involves chemical derivatisation, in which the zwitterionic acylcarnitines are cyclised to volatile lactones, and analysis by gas chromatography and gas chromatography--mass spectrometry. Preparation of urine samples by ion-exchange purification and an illustrative application of the proposed method to a clinical sample are also outlined.