Abstract

Precision medicine is becoming increasingly common in oncology, with treatments tailored to individual patients and cancer. By integrating these underlying concepts of health care, chemotherapy and radiotherapy can be tailored to improve safety and efficacy. On the other hand, oncology treatment regimens may result in local and systemic changes and complications depending on the type of treatment. For the proper and prompt management of cancer patients, it is essential to interpret this posttreatment imaging correctly. This article aims at guiding treating physicians to be able to distinguish complications from expected posttreatment changes.

Introduction

Precision medicine is becoming increasingly common in oncology, with treatments tailored to individual patients and cancer.[1] By integrating these underlying concepts of health care, chemotherapy and radiotherapy (RT) can be tailored to improve safety and efficacy.[2] On the other hand, oncology treatment regimens may result in local and systemic changes and complications depending on the type of treatment.[3] For the proper and prompt management of cancer patients, it is essential to interpret this posttreatment imaging correctly. This article aims at guiding treating physicians to be able to distinguish complications from expected posttreatment changes.

Etiopathogenesis and Risk Factors

Chemotherapy and radiation therapy impairs mucosal immunity. Stem cell transplantations and some chemotherapy agents result in neutropenia. These factors and other factors such as graft versus host disease, and the use of immunomodulatory agents increase the risk of infections in cancer patients during treatment.

Acute effects of RT are mainly on organs having rapid cell turnover, such as skin or mucosal surfaces. On the other hand, chronic or late complications of RT, such as fibrosis, perforation, or fistula formation, are a result of microvascular injury or direct parenchymal damage.[4]

Risk factors for treatment related complications are:

• Local extent and histology of the primary neoplasm.

• Preoperative chemotherapy and/or RT.

• Type of radiation therapy.

• Radiation dose, duration, and fractionation.

• Size of the field of irradiation.

• Concurrent use of chemotherapy.

• Comorbid medical conditions.

• Poor nutritional status.

Epidemiology, Clinical Presentation

Around 650,000 cancer patients receive systemic therapy or RT in the United States each year, while 180,000 receive both. The number of emergency department visits associated with cancer treatment outpaced visits related to overall health care. The most implicated cancers were lung (20.0%), breast (13.2%), and non-Hodgkin lymphoma (9.7%).

The most common complications in patients with hematologic malignancies were neutropenia (15.0%), sepsis (11.6%), and anemia (11.5%). In the case of solid tumor malignancies, the most frequent complications are sepsis (7.4%), neutropenia (7.3%), and anemia (6.7%).

Among the other common presentations, dehydration was among the most common complications associated with head and neck, colon, and esophageal cancers. Intestinal obstruction was commonly seen in gynecologic (ovary, uterus, and cervix) and gastrointestinal (GI) (colorectal and anal canal) cancers. GI hemorrhage was most commonly seen in prostate cancer. Congestive cardiac failure was commonly seen in breast cancer and non-Hodgkin lymphoma. Pneumonia was associated with lung cancer and multiple myeloma while acute kidney injury (AKI) was most commonly associated with urinary bladder cancer.[5]

Imaging Referral Guidelines

National Comprehensive Cancer Network (NCCN), European Society of Medical Oncology (ESMO), and American Society of Clinical Oncology (ASCO) clinical guidelines are available for the management of immunotherapy-related toxicities[6] and cancer-related infections.[7] These guidelines have also mentioned the management of treatment-related complications according to symptoms.

No consensus guidelines exist on the frequency and modality of routine posttreatment imaging in the asymptomatic patient. In the case of signs and symptoms or the presence of worrisome features on clinical examinations, imaging protocol may be tailored to answer specific clinical questions.

Most of the literature on imaging of complications of cancer therapy predominantly uses computed tomography (CT) and magnetic resonance imaging (MRI).

American College of Radiology (ACR) provided guidelines for the choice of imaging based on clinical presentation in the form of ACR appropriateness criteria. No specific guidelines are available on imaging of posttreatment complications in cancer.

National Cancer Grid (NCG) of India has formulated guidelines for palliative care of cancer but does not recommend imaging referral.[8] NCG, however, mentions the use of CT scans in cases where corrective measures are feasible and justifiable.[9]

Clinical/Diagnostic Workup (Other than Imaging)

Complications of systemic anticancer treatment are class-specific (i.e., agent-specific). A sepsis workup should be done if there is fever and/or cytopenia for localized or systemic features of inflammations (like intra-abdominal collection, pyelonephritis, etc.). Hypokalemia or paralytic ileus should be a differential diagnosis of intestinal obstruction. For suspected lung infection, sputum and blood culture sensitivity with Gram stain and/or bronchoalveolar lavage (BAL) is helpful. Opportunistic and atypical infection should be ruled out by organism-specific polymerase chain reaction test from BAL and/or nasopharyngeal swab. Many tyrosine kinase inhibitors cause lung injury which is a diagnosis of exclusion sometimes with a classical clinical presentation with radiological findings. There is no specific diagnostic test other than a rapid response to steroid and drug withdrawal and infrequent reappearance on rechallenge.

For meningeal enhancement, cerebrospinal fluid cytology, cell count, biochemistry, and/or microbiological culture should be performed before labeling as carcinomatous meningitis in a clinical context. For immune checkpoint inhibitor (ICI)-induced systemic complications, organ-specific diagnostic guidelines exist (NCCN, ESMO, and ASCO guidelines) and infection should be ruled out before giving high-dose steroids for immune-related adverse events (irAE). Blood-borne viral infection (i.e., hepatitis B, hepatitis C, human immunodeficiency virus) and Koch's should be ruled out before giving immunosuppressants like infliximab for the treatment of steroid-refractory irAE.

Imaging Guidelines

Screening

Currently, there is no evidence to support screening for complications that may develop as a result of treatment of cancers in the general population except for when they present with symptoms.

Diagnosis

Central Nervous System ([Table 1] and [2], [Fig. 1])

| Fig 1 :Radiation necrosis (A–D). One-year postradiation and temozolomide therapy for left temporal lobe glioblastoma. Fluid-attenuated inversion recovery (FLAIR) shows intermediate-hypointense signal areas (red arrow in A) in the left parietal lobe with surrounding disproportionate white matter edema. Contrast image (B) shows irregular and nodular enhancement (Swiss-cheese pattern) and relative cerebral blood volume (rCBV) perfusion (C) did not show any increased perfusion. Presence of lipid-lactate peak in the corresponding area on magnetic resonance (MR) spectroscopy (D) represents necrosis. These imaging features are typical for radiation-induced injury. Absence of increased choline:NAA ratios (D) further helps exclude tumor progression. Posterior reversible encephalopathy syndrome (PRES) (E). Bilaterally asymmetrical FLAIR hyperintensity in frontoparietal white matter suggestive of vasogenic edema. Acute arterial infarcts (F and G). FLAIR hyperintense areas (F) in right frontoparietal cortex and right basal ganglia due to cytotoxic edema, showing restriction on the corresponding diffusion-weighted image (G) are suggestive of watershed territory infarcts. Intracerebral hematoma (H). Acute hematoma in left occipital lobe appears hyperdense on noncontrast computed tomography (CT). There is an intraventricular extension of bleed into the left lateral ventricle. Subdural hematoma is noted along right cerebral convexity as well (red arrow in H). Chemotherapeutic agents are common inciting factors for PRES, cerebral hematoma, and arterial infarcts.

To establish the diagnosis of radiation (treatment)-related neurological complications, imaging is the first-line and most crucial investigation.[10] It also helps to rule out differential diagnosis such as metastases, tumor progression, hemorrhage, infarcts, and infections. MRI brain with intravenous contrast is the modality of choice. CT can be useful for quick assessment of raised intracranial tension, calcifications, acute hemorrhage, venous sinus thrombosis, or infarcts.

MRI angiogram with susceptibility-weighted imaging is preferred for evaluation of radiation-induced vascular injuries such as vascular narrowing or stenosis, capillary telangiectasia, cavernous malformations, microhemorrhages, and infarcts. CT can be useful for the detection of basal ganglia calcification associated with mineralizing microangiopathy.[11]

If patients with glioma are treated with RT and concurrent temozolomide after surgical resection, they become susceptible to radiation-related brain parenchymal damage, resulting in pseudoprogression and radiation necrosis.[12] The imaging modality of choice for radiation-related brain parenchymal injury is MRI with spectroscopy and perfusion. It helps to discriminate viable tumors from radiation necrosis/pseudoprogression.[13] Imaging guidelines are similar for radiation-induced necrosis associated with brain metastases following radiation therapy.[14] [15] [16]

MRI brain is the modality of choice for evaluation of chemotherapy-related neurotoxicity.[17] However, most drugs produce similar and nonspecific imaging patterns. The diagnosis can be established by resolution of MRI findings in post-drug cessation follow-up imaging. Few drugs have characteristic imaging findings and require additional MRI sequences to suggest the diagnosis. Areas of symmetrical diffusion restriction in white matter on diffusion-weighted imaging are most sensitive for detection of acute methotrexate toxicity post-intrathecal route of drug administration.[18] L-asparaginase cause venous sinus thrombosis which can be easily picked up on MRI with MR venography. Immunotherapeutic agents can cause autoimmune hypophysitis. MRI with pituitary sequences should be advised in this situation.

| Figure 2:(A) Expected radiotherapy (RT)-related soft tissue changes. Axial contrast-enhanced computed tomography (CT) image in soft tissue window shows diffuse bilateral symmetrical subcutaneous fat reticulations (notched white arrows), thickened bilateral platysma muscles (curved yellow arrows), increased enhancement of bilateral submandibular glands (black stars), and edema of hypopharyngeal structure (thin straight white arrows). (B) Radiation-induced osteonecrosis. Axial contrast-enhanced CT image in bone window shows bizarre lysis, fragmentation, and sclerosis of the mandible (thin straight yellow arrows). Absence of expansile soft tissue at site of bone destruction rules out the possibility of recurrence. (C) Radiation-induced fatty marrow conversion. Sagittal Dixon T1-weighted fat magnetic resonance (MR) image shows conversion to fatty marrow from C3-D4 vertebrae with sharp margins at mid-C2 and mid-D4 levels (thick white arrows) corresponding with the radiation portal. (D) Radiation-induced chondronecrosis. Axial noncontrast-enhanced CT image in bone window kernel shows lysis of thyroid cartilage (thick yellow arrow) with air foci in the vicinity of the right vocal cord. (E) Radiation-induced atherosclerosis. Axial contrast-enhanced CT image in soft tissue window shows fatty atherosclerotic mural changes in the left external carotid artery (thick red arrow) causing luminal stenosis.

Certain cancer treatments can damage the heart and the cardiovascular system and cause congestive heart failure, ischemia, hypertension, hypotension, and arrhythmias.[26]

Currently, posttreatment cardiac evaluation is most often performed with echocardiography which is the first line of imaging.[27] Previous history of cancer and cancer therapy are associated with increased coronary artery calcium scores. These patients often undergo chest CT scan for oncologic surveillance. It is important to note the presence and degree of coronary artery calcifications during these routine scans. Coronary CT is the imaging of choice for coronary artery disease characterization.[28]

Late sequelae of high-dose chest RT can cause constrictive pericarditis and valve stenosis.

CT scan or MRI can be used for evaluation of these entities.

Cardiac MRI is the noninvasive gold standard for morpho-functional myocardial characterization, thereby improving the detection of cardiotoxicity over conventional functional assessment. Nevertheless, the routine use of cardiac MRI is not currently recommended.[27] [29]

Other Thoracic Organs

For evaluation of pleura, pericardium, thymus, great vessels, and lymph nodes both CT and MRI can be used. CT scan is the modality of choice and is used more frequently. MRI is used as a problem solving tool.[25]

Abdomen ([Table 6], [Fig. 3])

| Figure 3:Imaging features of abdominal complications of cancer therapy. (A) A 53-year-old suffering from acute lymphoblastic leukemia, on treatment with steroids and L-asparaginase, presented with mild abdominal pain and hyperbilirubinemia. Axial noncontrast computed tomography (CT) scan shows markedly reduced density of the entire hepatic parenchyma (white asterisk), suggesting fatty liver. The vessels (white arrowhead) and spleen (S) appear hyperdense to hepatic parenchyma in this noncontrast phase of CT scan due to diffuse fatty infiltration. (B) A 61-year-old lady with metastatic carcinoma stomach, on treatment with oxaliplatin. Axial CT scan of the abdomen with intravenous (IV) contrast done after few cycles of chemotherapy shows heterogeneous enhancement of the hepatic parenchyma with linear hypodensitites (white arrows), which is new compared to the baseline CT scan done 3 months back, suggesting oxaliplatin-induced sinusoidal obstruction syndrome. (C) A 48-year-old man with lung adenocarcinoma, treated with pembrolizumab and carboplatin, presented to the emergency department (ED) complaining of abdominal pain, multiple episodes of diarrhea, and vomiting 6 days after a chemotherapy cycle. Sagittal CT scan of the abdomen with IV contrast shows thickened and edematous wall of ascending colon (A), caecum (C), and terminal ileum (TI), with surrounding fat stranding (yellow arrow), and maintained mural stratification. The patient was found to be severely neutropenic, and these imaging findings along with the clinical presentation, suggested neutropenic enterocolitis/typhlitis. (D) A 6-year-old boy suffering from acute lymphoblastic leukemia, on treatment regimen containing L-asparaginase, presented to the ED with acute abdominal pain and vomiting. He was found to be hypotensive and serum amylase and lipase were raised. Axial CT scan of the abdomen with IV contrast shows nonenhancing areas within the pancreatic parenchyma indicating necrosis (yellow arrowheads), and collection in peripancreatic region containing foci of fat (yellow asterisk). The features suggest acute necrotizing pancreatitis with peripancreatic fat necrosis. (E) A 47-year-old lady receiving radiation therapy for carcinoma of the cervix uteri, underwent response assessment magnetic resonance imaging (MRI) after 20 fractions along with cisplatin. Axial T2-weighted MR image shows submucosal edema as hyperintense signals (white block arrow) deep to the hypointense mucosal layer (black arrow), and maintained mural stratification, involving pelvic small bowel loops, indicating radiation-induced enteritis. The tumor with posttreatment changes is seen involving the cervix (M). (F) A 32-year-old man with rectal adenocarcinoma, underwent a response assessment MRI after neoadjuvant chemoradiotherapy. He complained of mild lower urinary tract symptoms. Axial T2-weighted MR image shows edematous wall of urinary bladder (UB), with hyperintense signals involving the submucosa and muscularis (yellow block arrow), and surrounding edematous pelvic fat (F). The features suggested radiation-induced cystitis.

Liver injury symptoms include fatigue, right upper quadrant pain, nausea, vomiting, jaundice, abdominal swelling, and skin rashes. The different mechanisms of action of chemotherapy and RT may result in a broad spectrum of pathological and radiological hepatic injuries. These include acute or chronic hepatitis, steatosis, fibrosis, pseudocirrhosis, sinusoidal changes, and nodular hyperplasia. Ultrasonography (USG) is performed initially to rule out metastases, hemorrhage, and obstructive causes of jaundice. It may also detect ascites and gallbladder wall thickening (bystander effect). Either CT or MRI can be used for further characterization of liver involvement. MRI is more accurate in diagnosing steatosis/steatohepatitis, sinusoidal obstruction syndrome, and focal nodular hyperplasia-like nodules.[30] [31] [32]

For treatment-related oral mucosal and gingival ulceration, chemotherapy- and RT-induced nausea and vomiting (unless alternative causes are suspected, such as brain metastases or bowel obstruction), and uncomplicated mild diarrhea no imaging is needed.

For patients presenting with moderate or severe diarrhea, abdominopelvic CT scan with intravenous contrast needs to be done if complications such as enteritis, toxic megacolon, or abscess are suspected.[6] CT enterography may be performed in subacute or chronic situations.

Patients with suspected bowel obstruction (which may be due to complications of therapy such as stricture, adhesions, enteritis, and colitis) should undergo a supine abdominal radiograph as the initial investigation. Abdominopelvic CT scan with intravenous contrast would be needed to further localize and demonstrate the cause of obstruction. Subacute cases may be investigated with oral contrast fluoroscopy, small bowel follow-through or enema studies, CT, or MR enterography.

Patients with dysphagia, retrosternal pain, and odynophagia, that is, suspected esophagitis, endoscopy would be needed. Fluoroscopic examination (contrast swallow studies) may be done in subacute presentation. For suspected esophageal stricture, fibrosis, or fistula, fluoroscopy examination and/or CT scan with oral and intravenous contrast would be needed.

If a patient presents with upper abdominal pain, epigastric tenderness, and vomiting, radiation-induced gastritis or gastric/duodenal ulceration would be a possible cause, for which endoscopy would be diagnostic and no imaging would be required.

In case these symptoms are associated with raised serum amylase and lipase, acute pancreatitis is suspected, and an abdominopelvic CT scan with intravenous contrast is indicated. If the scan is normal, magnetic resonance cholangiopancreatography may be considered.

Neutropenic patients presenting with acute abdominal pain, fever, vomiting, and diarrhea, would be suspected to have infective or noninfective colitis/enterocolitis. USG would be recommended as an initial investigation and abdominopelvic CT scan with intravenous contrast would be indicated.

For patients with suspected urinary tract infection presenting with fever, burning micturition, hematuria, and/or pyuria, USG would be the initial imaging. Patients on cytotoxic chemotherapy (such as cyclophosphamide) or RT presenting with hematuria, hemorrhagic cystitis can be due to the therapy or viral infections. Cystoscopy and urinary tract imaging is indicated in refractory and severe cases. If renal function allows, CT urogram is done, otherwise, MR urogram and renal USG may be performed.[33] Patients with rising urea and creatinine would be suspected to have AKI or chronic kidney disease in appropriate setting. Usually, USG is performed. MRI may be done to evaluate the kidney and other organs.

If female patients on pelvic radiation therapy present with lower abdominal pain and distension, cervical stenosis with hematometra or pyometra is a possibility. USG would be the initial investigation of choice. MRI of the pelvis would demonstrate the cause better. Patients presenting with urinary incontinence, urine, or stool discharge through vagina would be suspected to have fistulas, and fluoroscopic examination with relevant contrast is the initial investigation. CT scan of the pelvis with intravenous contrast (delayed phase images) or with rectal contrast will delineate the communication better. MRI of the pelvis or MR fisulogram may demonstrate some fistulous communications better. In patients who present with difficulty in micturition following radiation therapy, urethral strictures are suspected and retrograde cystourethrography/voiding cystourethrography are required imaging modalities for diagnosis.

Bones and Soft Tissues ([Table 7])

The imaging recommendations are given in [Table 7].[34] [35] [36]

Follow-Up and Surveillance

Women who were exposed to thoracic irradiation as an adolescent should undergo routine follow-up screening (with adjunctive breast MRI) sooner than usually recommended. Mammographic screening is recommended annually by the Society of Breast Imaging, ACR, and NCCN beginning 8 to 10 years after the radiation exposure.[37] [38]

For patients undergoing combined chemotherapy and radiation therapy, imaging monitoring of left ventricular ejection function has been recommended at 2-year intervals.[39] Echocardiography is typically used. In patients who are found to have decreased systolic function, the next step should be cardiac MRI.[40]

There exists no other substantial role for surveillance to detect treatment-related complications.

Principles of Management

Most of the grade 1or grade 2 systemic anticancer drug-related and RT toxicity is manageable with supportive care without altering the recommended dose and frequency. For any grade 3 or grade 4 toxicity every effort should be made to find out any identifiable underlying factor(s) contributing to such toxicity (like uncontrolled comorbidity, poor nutritional status, etc.). Any correctable cause should be addressed accordingly. Majority of the time dose reduction is recommended in case of grade 3/4 toxicity. Prophylactic hematopoietic growth factor should be used liberally whenever indicated to reduce the incidence of febrile neutropenia. Permanent interruption is required in majority of grade 4 and few grade 3 toxicities. Patient counseling, home remedies, early identification, and treatment of toxicities are very important and effective strategy to maintain treatment compliance. For ICI-induced irAE, well-recommended and well-studied organ-specific guidelines exist (ASCO and ESMO guidelines). No dose reduction is recommended or permitted for any ICI-related irAE. Initial antibiotics cover and ruling out underlying or associated infection is recommended for any immunosuppressive therapy to treat irAE. Imaging is required to differentiate treatment complications from infection and tumor recurrence.

Summary of Recommendations

• There are no consensus guidelines regarding the frequency and modality of routine posttreatment imaging in an asymptomatic patient.

• In the case of equivocal signs and symptoms or presence of worrisome features on clinical examinations and other laboratory tests, imaging protocol may be tailored to answer specific clinical questions.

• Most imaging guidelines advocate the use of MRI and CT scan in complementary roles.

Conflict of Interest

None declared.

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41. Address for correspondence
    

    Sumit Mukhopadhyay, MD
    Department of Radiology and Imaging Sciences, Tata Medical Center
    Kolkata, West Bengal 700160
    India   
    Email: sumitmukhopadhyayrad@gmail.com
    
    

    Publication History

    Article published online:
    01 March 2023
    

    © 2023. The Author(s). This is an open access article published by Thieme under the terms of the Creative Commons Attribution License, permitting unrestricted use, distribution, and reproduction so long as the original work is properly cited. (https://creativecommons.org/licenses/by/4.0/)

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    5. Hypereosinophilic syndrome: considerations for the cardiologist
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| Fig 1 :Radiation necrosis (A–D). One-year postradiation and temozolomide therapy for left temporal lobe glioblastoma. Fluid-attenuated inversion recovery (FLAIR) shows intermediate-hypointense signal areas (red arrow in A) in the left parietal lobe with surrounding disproportionate white matter edema. Contrast image (B) shows irregular and nodular enhancement (Swiss-cheese pattern) and relative cerebral blood volume (rCBV) perfusion (C) did not show any increased perfusion. Presence of lipid-lactate peak in the corresponding area on magnetic resonance (MR) spectroscopy (D) represents necrosis. These imaging features are typical for radiation-induced injury. Absence of increased choline:NAA ratios (D) further helps exclude tumor progression. Posterior reversible encephalopathy syndrome (PRES) (E). Bilaterally asymmetrical FLAIR hyperintensity in frontoparietal white matter suggestive of vasogenic edema. Acute arterial infarcts (F and G). FLAIR hyperintense areas (F) in right frontoparietal cortex and right basal ganglia due to cytotoxic edema, showing restriction on the corresponding diffusion-weighted image (G) are suggestive of watershed territory infarcts. Intracerebral hematoma (H). Acute hematoma in left occipital lobe appears hyperdense on noncontrast computed tomography (CT). There is an intraventricular extension of bleed into the left lateral ventricle. Subdural hematoma is noted along right cerebral convexity as well (red arrow in H). Chemotherapeutic agents are common inciting factors for PRES, cerebral hematoma, and arterial infarcts.

| Figure 2:(A) Expected radiotherapy (RT)-related soft tissue changes. Axial contrast-enhanced computed tomography (CT) image in soft tissue window shows diffuse bilateral symmetrical subcutaneous fat reticulations (notched white arrows), thickened bilateral platysma muscles (curved yellow arrows), increased enhancement of bilateral submandibular glands (black stars), and edema of hypopharyngeal structure (thin straight white arrows). (B) Radiation-induced osteonecrosis. Axial contrast-enhanced CT image in bone window shows bizarre lysis, fragmentation, and sclerosis of the mandible (thin straight yellow arrows). Absence of expansile soft tissue at site of bone destruction rules out the possibility of recurrence. (C) Radiation-induced fatty marrow conversion. Sagittal Dixon T1-weighted fat magnetic resonance (MR) image shows conversion to fatty marrow from C3-D4 vertebrae with sharp margins at mid-C2 and mid-D4 levels (thick white arrows) corresponding with the radiation portal. (D) Radiation-induced chondronecrosis. Axial noncontrast-enhanced CT image in bone window kernel shows lysis of thyroid cartilage (thick yellow arrow) with air foci in the vicinity of the right vocal cord. (E) Radiation-induced atherosclerosis. Axial contrast-enhanced CT image in soft tissue window shows fatty atherosclerotic mural changes in the left external carotid artery (thick red arrow) causing luminal stenosis.

| Figure 3:Imaging features of abdominal complications of cancer therapy. (A) A 53-year-old suffering from acute lymphoblastic leukemia, on treatment with steroids and L-asparaginase, presented with mild abdominal pain and hyperbilirubinemia. Axial noncontrast computed tomography (CT) scan shows markedly reduced density of the entire hepatic parenchyma (white asterisk), suggesting fatty liver. The vessels (white arrowhead) and spleen (S) appear hyperdense to hepatic parenchyma in this noncontrast phase of CT scan due to diffuse fatty infiltration. (B) A 61-year-old lady with metastatic carcinoma stomach, on treatment with oxaliplatin. Axial CT scan of the abdomen with intravenous (IV) contrast done after few cycles of chemotherapy shows heterogeneous enhancement of the hepatic parenchyma with linear hypodensitites (white arrows), which is new compared to the baseline CT scan done 3 months back, suggesting oxaliplatin-induced sinusoidal obstruction syndrome. (C) A 48-year-old man with lung adenocarcinoma, treated with pembrolizumab and carboplatin, presented to the emergency department (ED) complaining of abdominal pain, multiple episodes of diarrhea, and vomiting 6 days after a chemotherapy cycle. Sagittal CT scan of the abdomen with IV contrast shows thickened and edematous wall of ascending colon (A), caecum (C), and terminal ileum (TI), with surrounding fat stranding (yellow arrow), and maintained mural stratification. The patient was found to be severely neutropenic, and these imaging findings along with the clinical presentation, suggested neutropenic enterocolitis/typhlitis. (D) A 6-year-old boy suffering from acute lymphoblastic leukemia, on treatment regimen containing L-asparaginase, presented to the ED with acute abdominal pain and vomiting. He was found to be hypotensive and serum amylase and lipase were raised. Axial CT scan of the abdomen with IV contrast shows nonenhancing areas within the pancreatic parenchyma indicating necrosis (yellow arrowheads), and collection in peripancreatic region containing foci of fat (yellow asterisk). The features suggest acute necrotizing pancreatitis with peripancreatic fat necrosis. (E) A 47-year-old lady receiving radiation therapy for carcinoma of the cervix uteri, underwent response assessment magnetic resonance imaging (MRI) after 20 fractions along with cisplatin. Axial T2-weighted MR image shows submucosal edema as hyperintense signals (white block arrow) deep to the hypointense mucosal layer (black arrow), and maintained mural stratification, involving pelvic small bowel loops, indicating radiation-induced enteritis. The tumor with posttreatment changes is seen involving the cervix (M). (F) A 32-year-old man with rectal adenocarcinoma, underwent a response assessment MRI after neoadjuvant chemoradiotherapy. He complained of mild lower urinary tract symptoms. Axial T2-weighted MR image shows edematous wall of urinary bladder (UB), with hyperintense signals involving the submucosa and muscularis (yellow block arrow), and surrounding edematous pelvic fat (F). The features suggested radiation-induced cystitis.

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