Fine structure of breast tissue on micro computed tomography a feasibility study

Micro-CT Microcalcification Analysis: A Scoping Review of Current Applications and Future Potential in Breast Cancer Research

Micro-computed tomography (micro-CT) is a non-destructive imaging technique that offers highly detailed, 3D visualizations of a target specimen. In the context of breast cancer, micro-CT has emerged as a promising tool for analyzing microcalcifications (MCs), tiny calcium deposits that can indicate at an early stage the presence of cancer. This review aimed to explore the current applications of micro-CT in analyzing breast MCs (ex vivo, animal models, and phantoms) and to identify potential avenues in scientific research. We followed PRISMA guidelines for scoping reviews, yielding 18 studies that met our criteria. The studies varied in their purposes: feasibility and optimization of micro-CT for breast cancer imaging and MC analysis/diagnosis, comparison with other imaging modalities, development of micro-CT scanners and processing algorithms, enhancement of MC detection through contrast agents, etc. In conclusion, micro-CT offers superior image quality and detailed visualization of breast tissue (especially tumor masses and MCs), surpassing traditional methods like mammography and approaching the level of detail of histology. It holds great potential to enhance our understanding of MC characteristics and breast pathologies when used as a supplementary tool. Further research will solidify its role in clinical practice and potentially expand its applications in breast cancer studies.

The Value of Micro-CT in the Diagnosis of Lung Carcinoma: A Radio-Histopathological Perspective

Micro-computed tomography (micro-CT) is a relatively new imaging modality and the three-dimensional (3D) images obtained via micro-CT allow researchers to collect both quantitative and qualitative information on various types of samples. Micro-CT could potentially be used to examine human diseases and several studies have been published on this topic in the last decade. In this study, the potential uses of micro-CT in understanding and evaluating lung carcinoma and the relevant studies conducted on lung and other tumors are summarized. Currently, the resolution of benchtop laboratory micro-CT units has not reached the levels that can be obtained with light microscopy, and it is not possible to detect the histopathological features (e.g., tumor type, adenocarcinoma pattern, spread through air spaces) required for lung cancer management. However, its ability to provide 3D images in any plane of section, without disturbing the integrity of the specimen, suggests that it can be used as an auxiliary technique, especially in surgical margin examination, the evaluation of tumor invasion in the entire specimen, and calculation of primary and metastatic tumor volume. Along with future developments in micro-CT technology, it can be expected that the image resolution will gradually improve, the examination time will decrease, and the relevant software will be more user friendly. As a result of these developments, micro-CT may enter pathology laboratories as an auxiliary method in the pathological evaluation of lung tumors. However, the safety, performance, and cost effectiveness of micro-CT in the areas of possible clinical application should be investigated. If micro-CT passes all these tests, it may lead to the convergence of radiology and pathology applications performed independently in separate units today, and the birth of a new type of diagnostician who has equal knowledge of the histological and radiological features of tumors.

Histology, OCT, and Micro-CT Evaluation of Coronary Calcification Treated With Intravascular Lithotripsy: Atherosclerotic Cadaver Study

BACKGROUND

Although intravascular lithotripsy (IVL) has been an emerging novel option to treat vascular calcification, the specific effects on histology have not been systematically examined.

OBJECTIVES

The authors examined the histologic effects of IVL on coronary calcified lesions from human autopsy hearts and evaluated the diagnostic ability of optical coherence tomography (OCT) and micro-computed tomography (CT) to detect calcium fracture as identified by the gold standard histology.

METHODS

Eight coronary lesions were treated with IVL, and 7 lesions were treated with 10 atm inflation using an IVL catheter balloon without lithotripsy pulses (plain old balloon angioplasty [POBA]). OCT and micro-CT imaging were performed before and after treatment, and the presence of calcium fracture was assessed. The frequency and size of fractures were measured and compared with the corresponding histology.

RESULTS

All 15 treated lesions were diagnosed as sheet calcium by histology. Histological evidence of calcium fracture was significantly greater in the IVL group compared with the POBA group (62.5% vs 0.0%; P = 0.01). Calcified lesions with fracture had a larger maximum arc degree of calcification (median 145.6 [IQR: 134.4-300.4] degrees vs 107.0 [IQR: 88.9-129.1] degrees; P = 0.01). Micro-CT and histology showed an excellent correlation for fracture depth (R2 = 0.83; P < 0.0001), whereas OCT showed less correlation (R2 = 0.37; P = 0.11). The depth of fractures measured by OCT were significantly shorter than with those measured by histology (0.49 [IQR: 0.29-0.77] mm vs 0.88 [IQR: 0.64-1.07] mm; P = 0.008).

CONCLUSIONS

IVL demonstrated a histologically superior fracturing effect on coronary calcified lesions compared with POBA. OCT failed to identify the presence of some calcium fractures and underestimated the depth of fracture when compared with micro-CT.

Co-Registration of Peripheral Atherosclerotic Plaques Assessed by Conventional CT Angiography, MicroCT and Histology in Patients with Chronic Limb Threatening Ischaemia

OBJECTIVE

To co-register conventional computed tomography angiography (CTA), with ex vivo micro-computed tomography (microCT) and histology of popliteal atherosclerotic plaques. Improving the non-invasive imaging capabilities may be valuable to advance patient care with peripheral arterial obstructive disease towards lesion and individual based treatment.

METHODS

In this prospective observational study, 12 popliteal arteries from 11 symptomatic patients who had undergone transfemoral amputations for chronic limb threatening ischaemia and who had pre-operative CTA, were analysed ex vivo by microCT and histology. A total of 353 histological cross sections were co-registered with microCT and CTA, and classified as: lipid rich (LP, n = 26), fibrous (FP, n = 80), or calcific (CP, n = 247) plaques. CTA and microCT plaque density was calculated in 791 regions of interest as Hounsfield units (HU).

RESULTS

CTA and microCT could identify plaque components that were confirmed by histology such as fibrous tissue (FP), lipid pool/core (LP), and calcification (CP). MicroCT densities were 77.8 HU for FP (IQR 52.8, 129.5 HU), -28.4 HU for LP (IQR -87.1, 13.2 HU), and 3826.0 HU for CP (IQR 2989.0, 4501.0 HU). CTA densities of the three components of the plaque were: 78.0 HU for FP (IQR 59.5, 119.8 HU), 32.5 HU for LP (IQR 15.0, 42 HU), and 641.5 HU for CP (IQR 425.8, 1135 HU). The differences were statistically significant between the HU densitometric characteristics among the three groups (p < .0001) for both imaging modalities. Overall, microCT performed better diagnostically than conventional CTA for the three types of plaques: areas under the receiving operator characteristics curve were greater for microCT than CTA for FP (0.97 vs. 0.90), for LP (0.88 vs. 0.67), and for CP (0.97 vs. 0.90).

CONCLUSION

CTA and microCT can be used to identify histological atherosclerotic plaque components, with better diagnostic performance for microCT. This study demonstrates the feasibility of using microCT to assess plaque morphology lesions in a manner that approaches histology thus becoming a useful tool for ex vivo assessment of atherosclerosis and towards lesion based treatment.

Investigation of optimal sample preparation conditions with potassium triiodide and optimal imaging settings for microfocus computed tomography of excised cat hearts

OBJECTIVE

To determine optimal sample preparation conditions with potassium triiodide (I₂KI) and optimal imaging settings for microfocus CT (micro-CT) of excised cat hearts.

SAMPLE

7 excised hearts (weight range, 10 to 17.6 g) obtained from healthy adult cats after euthanasia by IV injection of pentobarbital sodium.

PROCEDURES

Following excision, the hearts were preserved in 10% formaldehyde solution. Six hearts were immersed in 1.25% I₂KI solution (n = 3) or 2.5% I₂KI solution (3) for a 12-day period. Micro-CT images were acquired at time 0 (prior to iodination) then approximately every 24 and 48 hours thereafter to determine optimal sample preparation conditions (ie, immersion time and concentration of I₂KI solution). Identified optimal conditions were then used to prepare the seventh heart for imaging; changes in voltage, current, exposure time, and gain on image quality were evaluated to determine optimal settings (ie, maximal signal-to-noise and contrast-to-noise ratios). Images were obtained at a voxel resolution of 30 μm. A detailed morphological assessment of the main cardiac structures of the seventh heart was then performed.

RESULTS

Immersion in 2.5% I₂KI solution for 48 hours was optimal for sample preparation. The optimal imaging conditions included a tube voltage of 100 kV, current of 150 μA, and exposure time of 354 milliseconds; scan duration was 12 minutes.

CONCLUSIONS AND CLINICAL RELEVANCE

Results provided an optimal micro-CT imaging protocol for excised cat hearts prepared with I₂KI solution that could serve as a basis for future studies of micro-CT for high resolution 3-D imaging of cat hearts.

Method for coregistration of optical measurements of breast tissue with histopathology: the importance of accounting for tissue deformations

For the validation of optical diagnostic technologies, experimental results need to be benchmarked against the gold standard. Currently, the gold standard for tissue characterization is assessment of hematoxylin and eosin (H&E)-stained sections by a pathologist. When processing tissue into H&E sections, the shape of the tissue deforms with respect to the initial shape when it was optically measured. We demonstrate the importance of accounting for these tissue deformations when correlating optical measurement with routinely acquired histopathology. We propose a method to register the tissue in the H&E sections to the optical measurements, which corrects for these tissue deformations. We compare the registered H&E sections to H&E sections that were registered with an algorithm that does not account for tissue deformations by evaluating both the shape and the composition of the tissue and using microcomputer tomography data as an independent measure. The proposed method, which did account for tissue deformations, was more accurate than the method that did not account for tissue deformations. These results emphasize the need for a registration method that accounts for tissue deformations, such as the method presented in this study, which can aid in validating optical techniques for clinical use.

Feasibility of Micro-Computed Tomography Imaging for Direct Assessment of Surgical Resection Margins During Breast-Conserving Surgery

BACKGROUND

To analyze the feasibility and accuracy of micro-computed tomography (micro-CT) for surgical margin assessment in breast excision specimen.

MATERIALS AND METHODS

Two data sets of 30 micro-CT scans were retrospectively evaluated for positive resection margins by four observers in two phases, using pathology as a gold standard. Results of phase 1 were evaluated to define micro-CT evaluation guidelines for phase 2. Interobserver agreement was also assessed (kappa). In addition, a prospective study was conducted in which 40 micro-CT scans were directly acquired, reconstructed, and evaluated for positive resection margins by one observer. A suspect positive resection margin on micro-CT was annotated onto the specimen with ink, enabling local validation by pathology. Main outcome measures were accuracy, sensitivity, specificity, and positive predictive value (PPV).

RESULTS

Average accuracy, sensitivity, specificity, and PPV for the four observers were 63%, 38%, 70%, and 22%, respectively, in phase 1 and 72%, 40%, 78%, and 26%, respectively, in phase 2. The interobserver agreement was fair [kappa (range), 0.31 (0.12-0.80) in phase 1 and 0.23 (0-0.43) in phase 2]. In the prospective study 70% of the surgical resection margins were correctly evaluated. Ten specimens were annotated for positive resection margins, which correlated with three positive and three close (<1 mm) margins on pathology. Sensitivity, specificity, and PPV were 38%, 78%, and 30%, respectively.

CONCLUSIONS

Micro-CT imaging of breast excision specimen has moderate accuracy and considerable interobserver variation for analysis of surgical resection margins. Especially sensitivity and PPV need to be improved before micro-CT-based margin assessment can be introduced in clinical practice.

Micro-computed tomography (micro-CT) for intraoperative surgical margin assessment of breast cancer: A feasibility study in breast conserving surgery

PURPOSE

Around 15%-30% of patients receiving breast-conserving surgery (BCS) for invasive breast carcinoma or ductal carcinoma in situ (DCIS) need a reoperation due to tumor-positive margins at final histopathology. Currently available intraoperative surgical margin assessment modalities all have specific limitations. Therefore, we aimed to assess the feasibility and accuracy of micro-computed tomography (micro-CT) as a novel method for intraoperative margin assessment in BCS.

METHODS

Lumpectomy specimens from 30 consecutive patients diagnosed with invasive breast cancer or DCIS were imaged using a micro-CT. Margin status was assessed on micro-CT images by two investigators who were blinded to the final histopathological margin status. The micro-CT margin status was compared with the histopathological margin status.

RESULTS

The margin status could be assessed by micro-CT in 29 out of 30 patients. Of these, nine patients had a positive tumor margin and 20 a negative tumor margin at final histopathology. Margin status evaluation by micro-CT took always less than 15 min. The margin status in 25 patients was correctly predicted by micro-CT. There were four false-negative predictions. The accuracy, sensitivity, specificity, positive predictive value and negative predictive value of micro-CT in margin status prediction were 86%, 56%, 100%, 100% and 83%, respectively. With micro-CT, the positive margin rate could potentially have been reduced from 31% to 14%.

CONCLUSIONS

Whole lumpectomy specimen micro-CT scanning is a promising technique for intraoperative margin assessment in BCS. Intraoperative quick feedback on the margin status could potentially lead to a reduction in the number of reoperations.

Review of quantitative multiscale imaging of breast cancer

Breast cancer is the most common cancer among women worldwide and ranks second in terms of overall cancer deaths. One of the difficulties associated with treating breast cancer is that it is a heterogeneous disease with variations in benign and pathologic tissue composition, which contributes to disease development, progression, and treatment response. Many of these phenotypes are uncharacterized and their presence is difficult to detect, in part due to the sparsity of methods to correlate information between the cellular microscale and the whole-breast macroscale. Quantitative multiscale imaging of the breast is an emerging field concerned with the development of imaging technology that can characterize anatomic, functional, and molecular information across different resolutions and fields of view. It involves a diverse collection of imaging modalities, which touch large sections of the breast imaging research community. Prospective studies have shown promising results, but there are several challenges, ranging from basic physics and engineering to data processing and quantification, that must be met to bring the field to maturity. This paper presents some of the challenges that investigators face, reviews currently used multiscale imaging methods for preclinical imaging, and discusses the potential of these methods for clinical breast imaging.

Prediction of primary breast cancer size and T-stage using micro-computed tomography in lumpectomy specimens

Background:

Histopathology is the only accepted method to measure and stage the breast tumor size. However, there is a need to find another method to measure and stage the tumor size when the pathological assessment is not available. Micro-computed tomography. (micro-CT) has the ability to measure tumor in three dimensions in an intact lumpectomy specimen. In this study, we aimed to determine the accuracy of micro-CT to measure and stage the primary tumor size in breast lumpectomy specimens, as compared to the histopathology.

Materials and Methods:

Seventy-two women who underwent lumpectomy surgery at the Massachusetts General Hospital Department of Surgery from June 2011 to September 2011, and from August 2013 to December 2013 participated in this study. The lumpectomy specimens were scanned using micro-CT followed by routine pathological processing. The maximum dimension of the invasive breast tumor was obtained from the micro-CT image and was compared to the corresponding pathology report for each subject.

Results:

The invasive tumor size measurement by micro-CT was underestimated in 24 cases. (33%), overestimated in 37 cases. (51%), and matched it exactly in 11 cases. (15%) compared to the histopathology measurement for all the cases. However, micro-CT T-stage classification differed from histopathology in only 11. (15.2%) with 6 cases. (8.3%) classified as a higher stage by micro-CT, and 5 cases. (6.9%) classified as lower compared to histopathology. In addition, micro-CT demonstrated a statically significant strong agreement (κ =0.6, P < 0.05) with pathological tumor size and staging for invasive ductal carcinoma. (IDC) group. In contrast, there was no agreement. (κ = −2, P = 0.67) between micro-CT and pathology in estimating and staging tumor size for invasive lobular carcinoma. (ILC) group. This could be explained by a small sample size. (7) for ILC group.

Conclusions:

Micro-CT is a promising modality for measuring and staging the IDC.

Intraoperative micro-computed tomography (micro-CT): a novel method for determination of primary tumour dimensions in breast cancer specimens

OBJECTIVES

Micro-CT is a promising modality to determine breast tumour size in three dimensions in intact lumpectomy specimens. We compared the accuracy of tumour size measurements using specimen micro-CT with measurements using multimodality pre-operative imaging.

METHODS

A tabletop micro-CT was used to image breast lumpectomy specimens. The largest tumour dimension on three-dimensional reconstructed micro-CT images of the specimen was compared with the measurements determined by pre-operative mammography, ultrasound and MRI. The largest dimension of pathologic invasive cancer size was used as the gold standard reference to assess the accuracy of imaging assessments.

RESULTS

50 invasive breast cancer specimens in 50 patients had micro-CT imaging. 42 were invasive ductal carcinoma, 6 were invasive lobular carcinoma and 2 were other invasive cancer. Median patient age was 63 years (range 33-82 years). When compared with the largest pathologic tumour dimension, micro-CT measurements had the best correlation coefficient (r = 0.82, p < 0.001) followed by MRI (r = 0.78, p < 0.001), ultrasound (r = 0.61, p < 0.001) and mammography (r = 0.40, p < 0.01). When compared with pre-operative modalities, micro-CT had the best correlation coefficient (r = 0.86, p < 0.001) with MRI, followed by ultrasound (r = 0.60, p < 0.001) and mammography (r = 0.54, p < 0.001). Overall, mammography and ultrasound tended to underestimate the largest tumour dimension, while MRI and micro-CT overestimated the largest tumour dimension more frequently.

CONCLUSION

Micro-CT is a potentially useful tool for accurate assessment of tumour dimensions within a lumpectomy specimen. Future studies need to be carried out to see if this technology could have a role in margin assessment.

ADVANCES IN KNOWLEDGE

Micro-CT is a promising new technique which could potentially be used for rapid assessment of breast cancer dimensions in an intact lumpectomy specimen in order to guide surgical excision.

The importance of surgical margins in breast cancer

Achieving negative margins with "no tumor on ink" is an appropriate goal in breast conserving therapy (BCT). Wider margins do not decrease recurrence rates, and re-excision in patients with microscopic positive margins is warranted. Several strategies exist to increase rates of negative margins, including techniques to improve tumor localization, intraoperative assessment of margins and oncoplastic techniques. Negative margins should be the goal of BCT, as this will improve both local control and long-term survival.

Intraoperative assessment of margins in breast conservative surgery--still in use?

A positive margin in breast conserving surgery is associated with an increased risk of local recurrence. Failure to achieve clear margins results in re-excision procedures. Methods for intraoperative assessment of margins have been developed, such as frozen section analysis, touch preparation cytology, near-infrared fluorescence optical imaging, x-ray diffraction technology, high-frequency ultrasound, micro-CT, and radiofrequency spectroscopy. In this article, options that might become the method of choice in the future are discussed.

Future directions for monitoring treatment responses in breast cancer

In the prior review, we outlined the current standard of care for monitoring treatment responses in breast cancer and discussed the many challenges associated with these strategies. We described the challenges faced in common clinical settings such as the adjuvant setting, neoadjuvant setting, and the metastatic setting. In this review, we will expand upon future directions meant to overcome several of these current challenges. We will also explore several new and promising methods under investigation to enhance how we monitor treatment responses in breast cancer. Furthermore, we will highlight several new technologies and techniques for monitoring breast cancer treatment in the adjuvant, neoadjuvant and metastatic setting.

A pilot study evaluating shaved cavity margins with micro-computed tomography: a novel method for predicting lumpectomy margin status intraoperatively

Microscopically clear lumpectomy margins are essential in breast conservation, as involved margins increase local recurrence. Currently, 18-50% of lumpectomies have close or positive margins that require re-excision. We assessed the ability of micro-computed tomography (micro-CT) to evaluate lumpectomy shaved cavity margins (SCM) intraoperatively to determine if this technology could rapidly identify margin involvement by tumor and reduce re-excision rates. Twenty-five SCM from six lumpectomies were evaluated with a Skyscan 1173 table top micro-CT scanner (Skyscan, Belgium). Micro-CT results were compared to histopathological results. We scanned three SCM at once with a 7-minute scanning protocol, and studied a total of 25 SCM from six lumpectomies. Images of the SCM were evaluated for radiographic signs of breast cancer including clustered microcalcifications and spiculated masses. SCM were negative by micro-CT in 19/25 (76%) and negative (≥2 mm) by histopathology in 19/25 (76%). Margin status by micro-CT was concordant with histopathology in 23/25 (92%). Micro-CT overestimated margin involvement in 1/25 and underestimated margin involvement in 1/25. Micro-CT had an 83.3% positive predictive value, a 94.7% negative predictive value, 83.3% sensitivity, and 94.7% specificity for evaluation of SCM. Evaluation of SCM by micro-CT is an accurate and promising method of intraoperative margin assessment in breast cancer patients. The scanning time required is short enough to permit real-time feedback to the operating surgeon, allowing immediate directed re-excision.

Micro-computed tomography (Micro-CT): a novel approach for intraoperative breast cancer specimen imaging

Intraoperative radiographic examination of breast specimens is commonly performed to confirm excision of image-detected breast lesions, but it is not reliable for assessing margin status. A more accurate method of intraoperative breast specimen imaging is needed. Micro-CT provides quantitative imaging parameters, image rotation, and virtual "slicing" of intact breast specimens. We explored the use of micro-CT for assessment of a variety of clinical breast specimens. Specimens were evaluated with a table top micro-CT scanner, Skyscan 1173 (Skyscan, Belgium), with a 40-130 kV, 8 W X-ray source. Skyscan software for 3D image analysis (Dataviewer and CTVox) was employed to review 3D graphics of specimens. Scanning for 7 min and another 7 min for image reconstruction provided the desired resolution for breast specimens. Breast lumpectomy specimens, shaved cavity margins, mastectomy specimens, and axillary lymph nodes were imaged by micro-CT. The micro-CT images could be rotated in all directions and cross sections of internal portions of specimens could be visualized from any angle. This provided information about spatial orientation of masses and calcifications relative to margins in intact lumpectomy specimens. Micro-CT is a potentially useful tool for assessment of breast cancer specimens, allowing real-time analysis of tumor location in breast lumpectomy specimens or shaved cavity margins. Micro-CT may also be useful for assessing sentinel lymph nodes and mastectomy specimens.